# Cranial morphology and phylogenetic relationships of Amynodontidae Scott and Osborn, 1883 (Perissodactyla, Rhinocerotoidea)

Lea Veine-Tonizzo, Jérémy Tissier, Maia Bukhsianidze, Davit Vasilyan, Damien Becker

► To cite this version:

Lea Veine-Tonizzo, Jérémy Tissier, Maia Bukhsianidze, Davit Vasilyan, Damien Becker. Cranial morphology and phylogenetic relationships of Amynodontidae Scott and Osborn, 1883 (Perissodactyla, Rhinocerotoidea). Comptes Rendus. Palevol, 2023, 22 (8), pp.109-142. 10.5852/cr-palevol2023v22a8. hal-04090054

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# Cranial morphology and phylogenetic relationships of Amynodontidae Scott & Osborn, 1883 (Perissodactyla, Rhinocerotoidea)

Léa VEINE-TONIZZO, Jérémy TISSIER, Maia BUKHSIANIDZE, Davit VASILYAN & Damien BECKER

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# Cranial morphology and phylogenetic relationships of Amynodontidae Scott & Osborn, 1883 (Perissodactyla, Rhinocerotoidea)

## Léa VEINE-TONIZZO

Géosciences Rennes, UMR 6118, Université de Rennes 1, CNRS, 35000 Rennes (France)
*and* JURASSICA Museum, Route de Fontenais 21, CH-2900 Porrentruy (Switzerland)
*and* Department of Earth Sciences, Carleton University, 1125 Colonel By Drive,
Ottawa, ON, K1S 5B6 (Canada)
*and* Beaty Centre for Species Discovery, Canadian Museum of Nature,
PO Box 3443, Station D., Ottawa, ON, K1P 6P4 (Canada)
leaveinetonizzo@cmail.carleton.ca (corresponding author)

## Jérémy TISSIER

JURASSICA Museum, Route de Fontenais 21, CH-2900 Porrentruy (Switzerland)
*and* American Museum of Natural History, Central Park West at 79th Street,
US-10024 New York (United States)
jeremy.tissier123@gmail.com

## Maia BUKHSIANIDZE

Georgian National Museum, 3, Purtseladze street, Tbilisi 0105 (Georgia)
maiapukh@gmail.com

## Davit VASILYAN
Damien BECKER

JURASSICA Museum, Route de Fontenais 21, CH-2900 Porrentruy (Switzerland)
*and* Department of Geosciences, University of Fribourg, CH-1700 Fribourg (Switzerland)
davit.vasilyan@jurassica.ch
damien.becker@jurassica.ch

Submitted on 2 February 2021 | Accepted on 27 January 2022 | Published on 20 March 2023

urn:lsid:zoobank.org:pub:3201699E-0180-4DB2-9C25-60EE6A783D85

Veine-Tonizzo L., Tissier J., Bukhsianidze M., Vasilyan D. & Becker D. 2023. — Cranial morphology and phylogenetic relationships of Amynodontidae Scott & Osborn, 1883 (Perissodactyla, Rhinocerotoidea). *Comptes Rendus Palevol* 22 (8): 109-142. https://doi.org/10.5852/cr-palevol2023v22a8

## ABSTRACT

Amynodontidae Scott & Osborn, 1883 are an extinct family of Rhinocerotoidea Owen, 1845 known from the middle Eocene to the latest Oligocene of Asia, North America, and Europe. We report here two unpublished specimens of Amynodontidae, a skull and a mandible of *Zaisanamynodon borisovi* Belyaeva, 1971 from the late Eocene of the Zaysan Basin (Kazakhstan) and a skull of *Metamynodon planifrons* Scott & Osborn, 1887, from the early Oligocene of the Big Badlands (United States). This new material has been incorporated into a morpho-anatomical character matrix. It was completed with the coding of the recently described species of *Amynodontopsis jiyuanensis* Wang X.-Y., Wang Y.-Q., Zhang R., Zhang Z.-H., Liu & Ren, 2020 and the revised coding of *Cadurcotherium*
**KEY WORDS**

Amynodontidae,
*Zaisanamynodon*,
*Metamynodon*,
phylogeny,
skull,
Zaysan Basin,
Big Badlands,
Eocene,
Oligocene,
Rhinocerotoidea.

**MOTS CLÉS**

Amynodontidae,
*Zaisanamynodon*,
*Metamynodon*,
phylogénie,
crâne,
Bassin Zaïssan,
Big Badlands,
Eocène,
Oligocène,
Rhinocerotoidea.

cayluxi Gervais, 1873 and *Cadurcotherium minum* Filhol, 1880. We computed a cladistic analysis based on this matrix, including 31 Rhinocerotoidea terminal taxa. The new phylogenetic hypothesis proposed allows to discuss the relationships of the referred specimens within Amynodontidae and those of Amynodontidae within Rhinocerotoidea. Our cladistic analysis clarifies the generic and specific composition of the tribes Metamynodontini Kretzoi, 1942 and Cadurcodontini Wall, 1982 and supports the monophyly of the genus *Zaisanamynodon* Belyaeva, 1971. The dichotomy between the two tribes is notably expressed by the presence of several cranial features such as “the deep nasal notch” or “the well-developed preorbital fossa” in Cadurcodontini. These cranial specializations attest to an adaptation of the peri-nasal region to the presence of a proboscis with a feeding function. Our study also opens a discussion on the biogeography of Amynodontidae, their emergence and dispersal in Asia and their subsequent migration to North America, and Eastern Europe. Their presence in Western Europe remains restricted to the Oligocene, after a dispersal related to the “Grande Coupure” event.

## RÉSUMÉ

*Morphologie crânienne et relations phylogénétiques des Amynodontidae Scott & Osborn, 1883 (Perissodactyla, Rhinocerotoidea).*

Les Amynodontidae Scott & Osborn, 1883 sont une famille éteinte de Rhinocerotoidea Owen, 1845 connue depuis l'Éocène moyen jusqu'à la fin de l'Oligocène en Asie, en Amérique du Nord et en Europe. Nous présentons ici deux spécimens inédits d'Amynodontidae, un crâne et une mandibule, de *Zaisanamynodon borisovi* Belyaeva, 1971, datés de la fin de l'Éocène du bassin de Zaïssan (Kazakhstan) et un crâne de *Metamynodon planifrons* Scott & Osborn, 1887, daté du début de l'Oligocène des Big Badlands (États-Unis). Ce nouveau matériel a été inclus dans une matrice de caractères morpho-anatomiques. Elle a été complétée par le codage de l'espèce récemment décrite *Amynodontopsis jiyuanensis* Wang X.-Y., Wang Y.-Q., Zhang R., Zhang Z.-H., Liu & Ren, 2020 et les codages révisés de *Cadurcotherium cayluxi* Gervais, 1873 et *Cadurcotherium minum* Filhol, 1880. Nous avons réalisé une analyse cladistique basée sur cette matrice, incluant 31 taxons terminaux de Rhinocerotoidea. La nouvelle hypothèse phylogénétique proposée permet de discuter des positions phylogénétiques des spécimens étudiés au sein des Amynodontidae et de la position des Amynodontidae au sein des Rhinocerotoidea. Notre analyse cladistique clarifie la composition générique et spécifique des tribus Metamynodontini Kretzoi, 1942 et Cadurcodontini Wall, 1982 et soutient la monophylie de *Zaisanamynodon* Belyaeva, 1971. La dichotomie des deux tribus s'exprime notamment par la présence de plusieurs caractéristiques craniennes telles que “l'allongement de l'incisure nasale” ou “la fosse préorbiteaire bien développée” chez les Cadurcodontini. Ces spécialisations témoignent d'une adaptation de la région péri-nasale à la présence d'un proboscis. Notre étude ouvre également une discussion sur la biogéographie des Amynodontidae, leur émergence et dispersion en Asie à l'Éocène moyen puis leur colonisation de l'Amérique du Nord et de l'Europe de l'Est. Leur présence en Europe occidentale est, quant à elle, restreinte à l'Oligocène et liée à l'événement de la Grande Coupure.

## INTRODUCTION

Amynodontidae Scott & Osborn, 1883 are an extinct family of hornless perissodactyls, which are included within Rhinocerotoidea Owen, 1845. They are assumed to be terrestrial herbivores but some of them were probably semi-aquatic (e.g. Wall 1982b, 1989, 1998; Wall & Heinbaugh 1999). They had a noticeable diversification during the middle and late Eocene in Asia and North America (e.g. Wall 1998; Averianov et al. 2016; Tissier et al. 2018). Amynodontidae were also present in Eastern Europe since the middle Eocene, and later during the Oligocene they are documented in Western Europe (e.g. Averianov et al. 2016; Tissier et al. 2018). This late dispersal would have been the consequence of establishment of land connections between Asia and Europe at the beginning of the Oligocene (i.e., the “Grande Coupure” event; Stehlin 1909; Legendre 1989; Hooker et al. 2004).

The monophyly of Amynodontidae is defined by well-supported synapomorphies such as the presence of a preorbital fossa, the loss of upper and lower P1, enlarged canines and the quadratic shape of the M3 (Wall 1980; Tissier et al. 2018). Relationships within Amynodontidae have been well studied since the 1940s (e.g. Wood 1941; Kretzoi 1942; Gromova 1954; Wall 1980). The first handmade phylogenetic analyses were performed by Wall (1982a, 1989, 1998) and, more recently, Averianov et al. (2016) and Tissier et al. (2018) published comprehensive phylogenies of the family based on computed cladistic analyses. Their new phylogenetic results led to a better understanding of the evolutionary history and the generic composition of the two major clades of the family: the Cadurcodontini Wall, 1982 and the Metamynodontini Scott & Osborn, 1887. Tissier et al. (2018) also underlined that suprageneric relationships within Rhinocerotoidea appear to be unclear, especially concerning
<figure><img src="image_6.png" /><figcaption>FIG. 1. — Biochronology, geography and stratigraphy information on cited localities: A, correlations between considered localities and temporal distributions of species described in the present paper; B, map of the area of the Lake Zaysan, Kazakhstan with locality of collect of ZSN-KKS-28-IPB; C, outcrop of the Aksyir Svita at Kiin Kerish (adapted from Lucas *et al.* 2012); D, map of Big Badlands, South Dakota, United States with supposed area of collect of UNISTRA.2015.0.1106; E, outcrop of the Scenic Member (Oreodon zone) of the Brule Formation of the White River Group (adapted from Benton *et al.* 2015). Numbers: 1, Kiin Kerish, locality of collect of ZSN-KKS-28-IPB (48°07′52.2″N, 84°28′52.3″E); 2, supposed area of collect of UNISTRA.2015.0.11.06 (see Gillet 1960).</figcaption></figure>

the “Hyracodontidae” Cope, 1879 and basal taxa of Amynodontidae. Indeed, the position of Amynodontidae within the Rhinocerotoidea is conflictual according to the most recent phylogenies. According to Wang *et al.* (2016, 2018) and Tissier *et al.* (2018), Amynodontidae would be the sister-group of the Paraceratheriidae Osborn, 1923, whereas according to Bai *et al.* (2020), they would be either sister-group of the clade formed by *Eggysodon* Roman, 1910, Paraceratheriidae and Rhinocerotidae Gray, 1821 based on a parsimony analysis, or sister-group of the Hyracodontidae, Eggysodontidae Breuning, 1923, Paraceratheriidae and Rhinocerotidae based on a Bayesian tip-dating analysis. Therefore, more data is necessary to better understand the early diversification of the main families of Rhinocerotoidea, which can be done by documenting their taxonomical and morphological diversity.

Here, we describe an unpublished skull and mandible (ZSN-KKS-28-IPB) of Amynodontidae from the late Eocene of the Zaysan Basin (Kazakhstan) and another amynodontid skull (UNISTRA.2015.0.1106) from the early Oligocene of the Big Badlands (United States). These specimens have been included in a parsimony analysis of a morphological characters matrix.

It includes a large sample of Rhinocerotoidea and a comprehensive amynodontid sampling. Our sampling aims to infer the phylogenetic positions of the referred specimens within Amynodontidae and the position of Amynodontidae within Rhinocerotoidea. The results are also discussed within the scope of the peculiar cranio-dental anatomy of the Amynodontidae and their biogeographical distribution.

## MATERIAL AND METHODS

### MATERIAL

The specimen ZSN-KKS-28-IPB, is a fragmented skull with P2-M3 in connection with a fragmented mandible with p4-m3. It was collected by Prof. Vyacheslav Chkhikvadze† in the 1980s and it is housed in the Georgian National Museum in Tbilisi, Georgia. The skull was found in the Kiin Kerish locality (48°07′52.2″N, 84°28′52.3″E) from the north of the Lake Zaysan, Kazakhstan. The fossiliferous layer is related to the Aksyir Svita. This stratigraphical unit is correlated to the Ergilian Asian Land Mammal Age (ALMA) which corresponds
A

<figure><img src="image_7.png" /></figure>

B

<figure><img src="image_8.png" /><figcaption>FIG. 2. — Dental terminology used for Amynodontidae Scott & Osborn, 1883: **A**, left P4-M1, hypothetical; **B**, right m2, hypothetical. Scale bar: 1 cm.</figcaption></figure>

to a late Eocene age (e.g. Russell & Zhai 1987; Lucas & Emry 1996; Emry *et al.* 1998; Lucas *et al.* 2012; Vandenberghe *et al.* 2012). The section of the Aksyir Svita at the Kiin Kerish locality is characterized by alternation of claystones, siltstones, sandstones (Borisov 1963; Lucas *et al.* 2012), which most probably represent fluvio-lacustrine deposits (Fig. 1A-C).

The specimen UNISTRA.2015.0.1106, is a well-preserved skull with right C1 and both P2-M3 series. It is housed in the collections of the "École et observatoire des sciences de la terre de Strasbourg", Université de Strasbourg, France, and it was briefly described for the first time in Gillet *et al.* (1957) and then in Gillet (1960). UNISTRA.2015.0.1106 was found in southwestern South Dakota at the Big Badlands National Park, United States. It was collected in the mudstone beds of the lower part of the Scenic Member (*Oreodon* zone) of the Brule Formation of the White River Group somewhere between the Sheep Mountain Table and the Cuny Table (Gillet 1960; for further information about the White River Group see Benton *et al.* 2015). The mudstone beds of the lower part of the Scenic Member (*Oreodon* zone) are dated from the early Orellan North America Land Mammal Age (NALMA) and correspond to an early Oligocene age (Gillet 1960; Prothero & Emry 2004, Benton *et al.* 2015) (Fig. 1A, D, E).

## SURFACE SCANNING

Specimens were scanned with a structured-light surface scanner (Artec Space Spider) and the three-dimensional models were reconstructed using the Artec Studio 13 Professional software. The three-dimensional model of the specimen UNISTRA.2015.0.1106 is available in Veine-Tonizzo *et al.* (2023).

## MEASUREMENTS AND ANATOMICAL TERMINOLOGY

Dental terminology used is illustrated in Figure 2. Cranial terminology is from Antoine (2002). Dental measurements are taken according to Uhlig (1999). Measurements are given in millimeters, and they are in parentheses when estimated.

## PHYLOGENETIC ANALYSIS

The matrix consisted of 32 terminals scored across 298 anatomical characters (Appendix 1). It is mainly based on the variation by Tissier *et al.* (2018) of the character matrix by Antoine (2002). The sample of terminals consists of twenty-seven taxa previously coded (Antoine *et al.* 2010; Tissier *et al.* 2018), including *Tapirus terrestris* (Von Linnaeus, 1758) and *Hyrachyus eximius* Leidy, 1871 considered as outgroups for this analysis, eleven terminals forming the branching-group (*sensu* Antoine, 2002) composed of major groups of Rhinocerotoidea (i.e., early Rhinocerotoidea; Rhinocerotidae; “Hyracodontidae”: Eggysodontidae, Paraceratheriidae), and fourteen terminals of Amynodontidae Scott & Osborn, 1883. The sample also includes three new terminals of Amynodontidae: *Amynodontopsis jiyuanensis* Wang X.-Y., Wang Y.-Q., Zhang R., Zhang Z.-H., Liu & Ren, 2020, ZSN-KKS-28-IPB and UNISTRA.2015.0.1106. Additionally, the coding of *Cadurcotherium cayluxi* Gervais, 1873 and *Cadurcotherium minum* Filhol, 1880 were revised based on the recent publication of Ménouret (2018). The phylogeny of the Amynodontidae was recently revised by Averianov *et al.* (2016) and Tissier *et al.* (2018). The sample of terminals of this study was chosen to test the latter results by including the new referred specimens and the revised coding of *Cadurcotherium* Gervais, 1873 within Amynodontidae (Table 1). Hence, the cladistic analysis does not intend to resolve the full phylogeny of Rhinocerotoidea.

The complete list of characters used is available in Appendix 2. Character's coding is based on direct observations of specimens and/or on publications (photographs, descriptions, and illustrations). Italicized numbers refer to character numbers, their associate state is in parentheses.

The matrix is composed of the characters 1-282 from the sequence of Antoine (2002), including the characters 36, 60, 103 and 140 modified from the original sequence to form morphoclines by Tissier *et al.* (2018). The characters 283-289 are from the matrix of Tissier *et al.* (2018). The characters 290-297 are based on the characters 8, 9, 16, 23, 25, 39, 41 and 45 of Averianov *et al.* (2016). The character 298 is newly included here: P4 third posterior loph = 0, absent; 1, present.

The cladistic analysis was computed with the traditional search in TNT version 1.5 (Goloboff *et al.* 2008) and the heuristic search in PAUP* version 4.0a167 (Swofford 2002). In TNT, starting trees were obtained from Wagner trees. Thousand replications of addition-sequence were performed using the tree bisection reconnection (TBR) algorithm and saving ten trees per replicate. In PAUP*, starting trees for branch-swapping were obtained by stepwise addition sequence of 1000 random replicates, holding ten trees at each step.
Branch-swapping was run with the TBR algorithm and the MulTrees option. Decay Index (Bremer support) was calculated with the use of TreeRot.v3 (Sorenson & Franzosa 2007) and PAUP*. Bootstrap, consistency index (CI) and retention index (RI) were calculated with PAUP*.

ABBREVIATIONS

Institutions

<table><tr><td>AMNH</td><td>American Museum of Natural History, New York;</td></tr><tr><td>ANPIN</td><td>Palaeontological Institute of the Russian Academy of Sciences, Moscow;</td></tr><tr><td>IPB</td><td>former L. Davitashvili Institute of Palaeobiology, Tbilisi now part of the Georgian National Museum, Tbilisi;</td></tr><tr><td>MJSN</td><td>Jurassica Museum (formerly "Musée jurassien des sciences naturelles"), Porrentruy;</td></tr><tr><td>UNISTRA</td><td>Collections of the "École et observatoire des sciences de la terre de Strasbourg", Université de Strasbourg;</td></tr><tr><td>VPM</td><td>Vertebrate Paleontology Mammal collection of the Museum of Comparative Zoology of Harvard University, Cambridge.</td></tr></table>

Measurements

<table><tr><td>H</td><td>height;</td></tr><tr><td>L</td><td>length;</td></tr><tr><td>W</td><td>width.</td></tr></table>

Dental

<table><tr><td>c/C</td><td>lower/upper canine;</td></tr><tr><td>i/I</td><td>lower/upper incisor;</td></tr><tr><td>m/M</td><td>lower/upper molar;</td></tr><tr><td>p/P</td><td>lower/upper premolar.</td></tr></table>

Other

<table><tr><td>ALMA</td><td>Asian Land Mammal Age;</td></tr><tr><td>CI</td><td>consistency index;</td></tr><tr><td>NALMA</td><td>North America Land Mammal Age;</td></tr><tr><td>RI</td><td>retention index;</td></tr><tr><td>TBR</td><td>Tree bisection reconnection.</td></tr></table>

SYSTEMATIC PALAEONTOLOGY

Class MAMMALIA Linnaeus, 1758
Order PERISSODACTYLA Owen, 1848
Superfamily RHINOCEROTOIDEA Gray, 1821
Family AMYNODONTIDAE Scott & Osborn, 1883
Tribe CADURCODONTINI Wall, 1982

Genus *Zaisanamynodon* Belyaeva, 1971

*Procadurcodon* Gromova (Nomen nudum) 1960: 129.

*Zaisanamynodon* Belyaeva, 1971: 43.

TYPE SPECIES. — *Zaisanamynodon borisovi* Belyaeva, 1971.

INCLUDED SPECIES. — *Zaisanamynodon protheroi* Lucas, 2006.

EMENDED DIAGNOSIS. — Within Cadurcodontini, *Zaisanamynodon* differs from other genera (*Cadurcotherium*, *Amynodontopsis* Stock, 1933, and *Cadurcodon* Kretzoi, 1942) by the presence of a third

posterior loph on P4. *Zaisanamynodon* differs from *Cadurcotherium* by the absence of cement on cheek teeth, an oblique hypolophid on lower molars and a long metastyle on M1-2. *Zaisanamynodon* differs from *Amynodontopsis* in having a postfossette on M1 and the absence of a sagittal crest on the basilar process. *Zaisanamynodon* differs from *Cadurcodon* in having a well-developed coronoid process of the mandible, the presence of i1, a long metastyle on M1-2 and a weak paracone fold on M1-2.

DIAGNOSIS DISCUSSION. — Belyaeva (1971) and Lucas *et al.* (1996) mentioned the presence of a third loph on P4 in *Zaisanamynodon borisovi* and Lucas (2006) observed this characteristic in *Zaisanamynodon protheroi*. He considered this feature as a distinct trait of *Zaisanamynodon* from other genera of Metamynodontini, to which *Zaisanamynodon* formerly belonged. In fact, this character can be used to distinguish *Zaisanamynodon* from all genera of Amynodontidae.

*Zaisanamynodon borisovi* Belyaeva, 1971
(Figs 3; 4; Table 2)

*Zaisanamynodon borisovi* Belyaeva, 1971: 43.

TYPE MATERIAL. — **Holotype.** ANPIN 2761/1-22, incomplete skull, lower jaw, and part of the postcranial skeleton, including most of the cervical vertebrae and forelimbs (Belyaeva 1971).

REFERRED MATERIAL. — ZSN-KKS-28-IPB, fragmentary skull with P2-M3 in connection with a fragmentary mandible with p4-m3. MJSN.2020.008.01 and MJSN.2020.008.02 are 3D-printed copies of this skull and mandible, respectively.

TYPE LOCALITY AND HORIZON. — Kiin Kerish locality (48°07′52.2″N, 84°28′52.3″E), north-west of Kiin Kerish Mountain, Kazakhstan. Lower Aksyr Svita, Ergilian ALMA (36.5-33.9 Ma) (i.e., late Eocene) (Borisov 1963; Belyaeva 1971; Russell & Zhai 1987; Lucas & Emry 1996; Lucas *et al.* 1996; Emry *et al.* 1998; Vandenberghe *et al.* 2012).

EMENDED DIAGNOSIS. — Differs from *Zaisanamynodon protheroi* in having a relatively short rostrum (about 12% of skull length), an anterior margin of the orbit above M1, incisors relatively large (especially I3/i3), a P2 less complex without anterior and posterior crests connected to the metaloph, a weak paracone fold on M3, lower canine relatively slender and curved, p3 more molariform, and a slight labial groove (cleft) between trigonid and talonid on lower molars.

DIAGNOSIS DISCUSSION. — In the revised diagnosis of *Z. borisovi* in Lucas (2006), the “lack of a complete cingulum” on P2-4 is considered as a character to distinguish *Z. borisovi* from *Zaisanamynodon protheroi*. However, in the original diagnosis of *Zaisanamynodon borisovi*, Belyaeva (1971) mentioned the presence of a well-developed anteroposterior and lingual collar (i.e., cingulum) and a weak labial collar (i.e., cingulum) on the upper premolars. In the description of Chinese specimens of *Z. borisovi*, Lucas *et al.* (1996) indicated the presence of a “complete lingual cingulum” on P2-3, and a “postero-lingual cingulum” on P4, which has been confirmed after direct observation of the specimen AMNH.26034. This feature is also observed on the studied material (ZSN-KKS-28-IPB). Therefore, the lingual cingulum on P2-4 can no longer be considered as a diagnostic character to distinguish *Z. protheroi* from *Z. borisovi*.

DESCRIPTION

Skull and mandible

The skull ZSN-KKS-28-IPB (Fig. 3A, B) is incomplete, deformed and some parts are covered by matrix. The maxilla is incomplete, and only the left anterior part of the jugal is still preserved. The anterior margin of the orbit is above
<table><caption>TABLE 1. — List of perissodactyl taxa (Rhinocerotoidea Owen, 1845 plus *Tapirus terrestris* (Linnaeus, 1758)) included in the phylogenetic analysis and their sources of coding.</caption><thead><tr><th rowspan="2">Terminal</th><th colspan="2">Sources of character coding</th></tr><tr><th>Direct observations</th><th>References</th></tr></thead><tbody><tr><td>Aceratherium incisivum Kaup, 1832</td><td>-</td><td>Antoine et al. (2010); Tissier et al. (2018)</td></tr><tr><td>Allacerops turgaica (Borissiak, 1918)</td><td>-</td><td>Tissier et al. (2018)</td></tr><tr><td>Amynodon advenus (Marsh, 1875)</td><td>-</td><td>Tissier et al. (2018)</td></tr><tr><td>Amynodontopsis bodei Stock, 1939</td><td>-</td><td>Tissier et al. (2018)</td></tr><tr><td>Amynodontopsis jiyuanensis Wang X.-Y., Wang Y.-Q., Zhang R., Zhang Z.-H., Liu & Ren, 2020</td><td>-</td><td>Wang et al. (2020)</td></tr><tr><td>Cadurcodon ardynensis (Osborn, 1923)</td><td>-</td><td>Tissier et al. (2018)</td></tr><tr><td>Cadurcodon bahoensis Xu, 1965</td><td>-</td><td>Tissier et al. (2018)</td></tr><tr><td>Cadurcodon kazakademius Biryukov, 1961</td><td>-</td><td>Tissier et al. (2018)</td></tr><tr><td>Cadurcodon maomingensis Averianov, Danilov, Jin & Wang, 2016</td><td>-</td><td>Tissier et al. (2018)</td></tr><tr><td>Cadurcotherium cayluxi Gervais, 1873</td><td>-</td><td>Collection « Le Garouillas » in De Bonis (1995) and Ménouret (2018)</td></tr><tr><td>Cadurcotherium minum Filhol, 1880</td><td>-</td><td>Ménouret (2018)</td></tr><tr><td>Eggysodon osborni (Schlosser, 1902)</td><td>-</td><td>Tissier et al. (2018)</td></tr><tr><td>Hyrachyus eximius Leidy, 1871</td><td>-</td><td>Antoine et al. (2010)</td></tr><tr><td>Hyracodon nebraskensis Leidy, 1850</td><td>-</td><td>Tissier et al. (2018)</td></tr><tr><td>ZSN-KKS-28-IPB</td><td>IPB, MJSN</td><td>-</td></tr><tr><td>Megalamynodon regalis Scott, 1945</td><td>-</td><td>Tissier et al. (2018)</td></tr><tr><td>Metamynodon planifrons Scott & Osborn, 1887</td><td>-</td><td>Tissier et al. (2018)</td></tr><tr><td>“Pappaceras” meiomenus Wang H.-B., Bai, Meng & Wang Y.-Q., 2016</td><td>-</td><td>Tissier et al. (2018)</td></tr><tr><td>Paraceratherium bugtiense (Pilgrim, 1908)</td><td>-</td><td>Tissier et al. (2018)</td></tr><tr><td>Paraceratherium transouralicum (Pavlova, 1922)</td><td>-</td><td>Tissier et al. (2018)</td></tr><tr><td>Paramynodon birmanicus (Pilgrim & Cotter, 1916)</td><td>-</td><td>Tissier et al. (2018)</td></tr><tr><td>Ronzotherium filholi (Osborn, 1900)</td><td>-</td><td>Antoine et al. (2010); Tissier et al. (2018)</td></tr><tr><td>Rostriamynodon grangeri Wall & Manning, 1986</td><td>-</td><td>Tissier et al. (2018)</td></tr><tr><td>Sellamynodon zimborensis (Codrea & Suraru, 1989)</td><td>-</td><td>Tissier et al. (2018)</td></tr><tr><td>Sharamynodon mongoliensis (Osborn, 1936)</td><td>-</td><td>Tissier et al. (2018)</td></tr><tr><td>Tapirus terrestris (Von Linnaeus, 1758)</td><td>-</td><td>Antoine et al. (2010); Tissier et al. (2018)</td></tr><tr><td>Teletaceras radinskyi Hanson, 1989</td><td>-</td><td>Tissier et al. (2018)</td></tr><tr><td>Trigonias osborni Lucas, 1900</td><td>-</td><td>Antoine et al. (2010)</td></tr><tr><td>UNISTRA.2015.0.1106</td><td>UNISTRA</td><td>-</td></tr><tr><td>Urtinotherium intermedium (Chiu, 1962)</td><td>-</td><td>Tissier et al. (2018)</td></tr><tr><td>Zaisanamynodon borisovi Belyaeva, 1971</td><td>-</td><td>Tissier et al. (2018)</td></tr><tr><td>Zaisanamynodon protheroi Lucas, 2006</td><td>-</td><td>Tissier et al. (2018)</td></tr></tbody></table>

M1. The zygomatic process progressively diverges from the maxilla. It starts above the M2 and separates from it above the M3. The mandible ZSN-KKS-28-IPB (Fig. 4A, B) is incomplete; the most anterior part is absent. The corpus mandibulae has a straight ventral profile. Only the anterior part of the ramus is present, and it is vertical. The dental formula of the specimen is I ?/?, C ?/?, P 3/2? M 3/3. The upper and lower anterior dentition are not preserved. The dental wear of the cheek teeth is moderate, the crown height is low, and the enamel is wrinkled and corrugated. The right P2 is very worn. The left P2 is not preserved and the left M3 is covered by matrix. There is no cement, crochet or antecrochet. The left p3 is not preserved but the roots of the right p3 can be observed in occlusal view.

### Upper cheek teeth (Fig. 3C-G)

The upper premolars are not molarized and are very short compared to the molars (sensu Antoine 2002), with a LP3-4/ LM1-3 ratio ≤0.42. Premolars have a labial and lingual cingulum. The lingual cingulum is strong and continuous. The postfossette is wide. The P2 is very small. It bears a single labial cusp and probably had a single lingual one.

The labial cingulum is continuous. On P3-4, the protocone and the hypocone are fused into a single lingual cusp. The protocone is not constricted. The metaloph is directed posteriorlingually. The paracone fold is very strong, forming a well-developed vertical ridge. On P3, the protoloph is not joined to the ectoloph, whereas they are joined on P4. The hypocone and the metacone of P4 are separated, whereas they are joined for P3. There is a crista on P3 and on the left P4. There is a shallow groove separating the paracone and the metacone on the ectoloph of P4. The metaloph of P4 is very short and weak. P4 has a third loph (Fig. 3F), posterior to the metaloph and closing the postfossette. This third loph is thin, low, and discontinuous.

The upper molars have a π shape. They have a weak labial cingulum; a weak lingual cingulum is present in anterior and/or posterior parts of M2 and posterior part of M3 whereas lingual cingulum is lacking on M1. Therefore, character 109 (1) and character 114 (2) in the matrix are scored as “usually present” and “usually absent”, respectively (sensu Antoine 2002). There are no crista and cristella. The protocone is widened. The metaloph is short, continuous, and its width decreases between M1-3. The ectoloph is very long, straight,
<figure><img src="image_9.png" /><figcaption>FIG. 3. — Skull and upper cheek teeth of the amynodontid rhinocerotid *Zaisanamynodon borisovi* Belyaeva, 1971, ZSN-KKS-28-IPB, Kiin Kerish, Kazakhstan, late Eocene: **A**, **B**, skull, three-dimensional model with texture, occlusal (**A**) and left lateral views (**B**); **C-E**, close-up of the left cheek teeth series, P4-M2(3), three-dimensional model, occlusal (**C**), lateral (**D**), lingual (**E**) views; **F**, close-up of the left cheek teeth series, P4-M2, occlusal view; **G**, close-up of the left P4-M1, lingual view. Abbreviations: **j**, jugal; **mx**, maxilla; **o**, orbit. Scale bars: A, B, 5 cm; C-G, 2 cm.</figcaption></figure>

and smooth. The fold of the paracone is weak, and the parastyle is reduced. There is a postfossette on each molar. The metastyle on M1-2 is long. The M1-2 have a continuous posterior cin-

gulum. The M3 has a quadrangular shape. Its protoloph and metaloph are oblique to its ectoloph. Its metastyle is directed posterolingually. The ectoloph is concave labially.
<table><caption>TABLE 2. — Measurements (in mm) of the dentition of the amynodontid rhinocero-
toid *Zaisanamynodon borisovi* Belyaeva, 1971 ZSN-KKS-28-IPB. The width
measurements of P4-M3 are presented as follows: anterior/posterior orienta-
tion of the teeth. The measurements are in brackets when they are uncertain.</caption>
  <thead>
    <tr>
      <th rowspan="2">Tooth</th>
      <th colspan="2">Lenght</th>
      <th colspan="2">Width</th>
      <th colspan="2">Height</th>
    </tr>
    <tr>
      <th>Left</th>
      <th>Right</th>
      <th>Left</th>
      <th>Right</th>
      <th>Left</th>
      <th>Right</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>P2</td>
      <td>–</td>
      <td>24.5</td>
      <td>–</td>
      <td>(25.0)</td>
      <td>–</td>
      <td>28.0</td>
    </tr>
    <tr>
      <td>P3</td>
      <td>32.5</td>
      <td>31.0</td>
      <td>46.0</td>
      <td>44.0</td>
      <td>31.0</td>
      <td>32.5</td>
    </tr>
    <tr>
      <td>P4</td>
      <td>38.5</td>
      <td>38.0</td>
      <td>61.0 / 56.0</td>
      <td>60.0 / 50.0</td>
      <td>32.5</td>
      <td>32.0</td>
    </tr>
    <tr>
      <td>M1</td>
      <td>67.0</td>
      <td>70.0</td>
      <td>68.0 / 67.0</td>
      <td>68.0 / 65.0</td>
      <td>35.0</td>
      <td>39.0</td>
    </tr>
    <tr>
      <td>M2</td>
      <td>81.0</td>
      <td>81.0</td>
      <td>69.0 / 62.0</td>
      <td>60.0 / 40.0</td>
      <td>54.0</td>
      <td>57.0</td>
    </tr>
    <tr>
      <td>M3</td>
      <td>–</td>
      <td>82.5</td>
      <td>–</td>
      <td>47.0 / –</td>
      <td>–</td>
      <td>57.0</td>
    </tr>
    <tr>
      <td>p4</td>
      <td>37.0</td>
      <td>39.0</td>
      <td>30.5</td>
      <td>31</td>
      <td>35.0</td>
      <td>38.0</td>
    </tr>
    <tr>
      <td>m1</td>
      <td>57.0</td>
      <td>56.0</td>
      <td>36.5</td>
      <td>38.5</td>
      <td>38.0</td>
      <td>39.0</td>
    </tr>
    <tr>
      <td>m2</td>
      <td>75.0</td>
      <td>74.5</td>
      <td>45.0</td>
      <td>47.0</td>
      <td>49.5</td>
      <td>47.0</td>
    </tr>
    <tr>
      <td>m3</td>
      <td>82.0</td>
      <td>80.5</td>
      <td>40.0</td>
      <td>39.5</td>
      <td>50.0</td>
      <td>51.0</td>
    </tr>
  </tbody>
</table>

Lower cheek teeth (Fig. 4C-H)

The p4-m3 series have a continuous labial cingulum. The lingual cingulum is only interrupted below the hypoconid. The trigonid is obtuse and is smaller than the talonid. The trigonid and talonid are open on the lingual side. The talonid is equal to the trigonid on the p4-m1, whereas the talonid is longer than the trigonid on the m2-3. The metaconid and entoconid are not constricted. The ectolophid is completely smooth (no labial groove), except on the p4, which has very shallow ectolophid and paralophid grooves. The lingual opening of the posterior valley on the p4 is U-shaped. The lower molar series are long. They bear an oblique hypolophid.

Body mass

The body mass of ZSN-KKS-28-IPB was estimated to be around 4.1 tons with the regression equations of perissodactyls and ungulates of Legendre (1989) based on occlusal surface of m1 (Table 2; Appendix 3). The body mass was also estimated to be around 5.7 tons with the regression equations of Rhinocerotidae of Fortelius & Kappelman (1993), and 4.5 tons with the equations for all ungulates. They are based on the lengths of M2, M3 and the total upper tooth row (Table 2; Appendix 3). In most cases, our estimations are higher than those of Averianov *et al.* (2016) for *Zaisanamynodon borisovi* (“2442 ± 257 kg” see Averianov *et al.* (2016): supplemental table 2) with regression equation for generalized ungulates of Legendre (1989), except for the TRLU estimate (2.1 tons). This can be explained by the very large dimensions of the cheek teeth of the referred specimen as well as by the much bigger size of M2 and M3 (which are not used by Averianov *et al.* 2016), compared to the m1.

Furthermore, the body mass estimation obtained through
the Rhinocerotidae equations of Fortelius & Kappelman
(1993) based on M2 and M3 may also be extremely over-
estimated due to the difference of morphology of the teeth
of Amynodontidae compared with Rhinocerotidae. Indeed,
in Amynodontidae, the M2 and M3 tend to be much larger
than all other cheek teeth, which is not the case in Rhinoc-
erotidae. In addition, Amynodontidae retain a metastyle
on M3, leading to a quadrangular shape (and thus bigger

length), whereas Rhinocerotidae have a triangular M3,
without metastyle but an ectometaloph instead. Thus, these
values should not be taken at face value but only be used
for comparison if one uses the same method, since there are
currently non that is specifically made for the rather peculiar
amynodontid morphology.

Interestingly, the dimensions of the M2 and M3 of this specimen are comparable to those of the largest land-mammal that ever existed: *Paraceratherium* (= *Indricotherium*). For example, the length of M2 and M3 of *Paraceratherium bugtiense* is around 74 to 96 mm (Fortelius & Kappelman 1993), while our specimen measures 81 and 82 mm respectively. This explains the enormous body mass retrieved by our estimations. However, these estimations can be nuanced by the much shorter upper tooth row length (284 mm for ZSN-KKS-28-IPB against 400 mm for “*Indricotherium*” transouralicum), which is explained by the typical premolar reduction of the Amynodontidae. Therefore, *Zaisanamynodon borisovi* may still have been one of the largest Amynodontidae, but not as large as *Paraceratherium*.

REMARKS

ZSN-KKS-28-IPB can be referred to Rhinoceroidea based on the π shape of upper molars (Wall 1989). An attribution of ZSN-KKS-28-IPB to Amynodontidae is reliable based on the reduced dental formula, with the absence of the P1/p1-2, which is a derived character typical of Amynodontidae (Wall 1989; Tissier et al. 2018). ZSN-KKS-28-IPB shares other diagnostic characters of the Amynodontidae: the absence of the crochet; antecrochet; crista; the reduced parastyle on the upper molars; the quadratic M3 with a large metastyle and the elongated lower molars (Wall 1989; Tissier et al. 2018). Therefore, an attribution to Rhinocerotidae, Eggyodontidae, “Hyracodontidae” or Paraceratheriidae can be excluded.

According to our phylogenetic analysis, ZSN-KKS-28-IPB shares two diagnostic characters with Cadurcodontini: a talonid on m3 longer than the trigonid and the constant presence of labial cingulum on upper premolars. It also shares the absence of labial groove separating the trigonid and talonid on lower molars (Averianov *et al.* 2016).

Within Cadurcodontini, ZSN-KKS-28-IPB differs from *Cadurcotherium* in the absence of cement on cheek teeth, an oblique hypolophid on lower molars, and a long metastyle on M1-2. ZSN-KKS-28-IPB differs from *Amynodontopsis* in the presence of a postfossette on M1. ZSN-KKS-28-IPB differs from *Cadurcodon* in having a long metastyle on M1-2 and a weak paracone fold on M1-M2.

ZSN-KKS-28-IPB can be referred to *Zaisanamynodon* by the presence of a third posterior loph on P4, which is a diagnostic character of the genus (Lucas 2006). Belyaeva (1971), Lucas *et al.* (1996) and Lucas (2006) provided detailed descriptions, illustrations, and measurements of *Zaisanamynodon borisovi* and *Zaisanamynodon protheroi*. Following our emended diagnosis of *Z. borisovi*, ZSN-KKS-28-IPB shares a single diagnostic character of *Z. borisovi*: the anterior margin of the orbit above M1. However, ZSN-KKS-28-IPB differs from it by the absence of slight labial groove (cleft) between trigonid
<figure><img src="image_10.png" /><figcaption>FIG. 4. — Mandible and lower cheek teeth of the amynodontid rhinocerotid *Zaisanamynodon borisovi* Belyaeva, 1971 ZSN-KKS-28-IPB, Kiin Kerish, Kazakhstan, late Eocene: A, B, mandible, three-dimensional model with texture, occlusal (A), right lateral (B) views; C-E, close-up of the right cheek teeth series, p3-M3, three-dimensional model, lingual (C), occlusal (D), lateral (E) views; F, close-up of the right p4-m1, lingual view; G, H, close-up of the right cheek teeth series, p3-M3, occlusal (G), lateral (H) views. Scale bars: A, B, 5 cm; C-H, 2 cm.</figcaption></figure>

and talonid on lower molars, as in *Z. protheroi*. According to Lucas (2006), the complexity of the P2 and the presence of an “anterior and posterior crests connected to metaloph” are considered as differential diagnostic characters of the two species of *Zaisanamynodon*. This feature cannot be observed on ZSN-KKS-28-IPB because the right P2 is very worn and

the left one is missing. For this reason, we cannot use this character to exclude an attribution to *Z. protheroi* (Lucas 2006). In addition, the incisors, canines and p3, which also bear diagnostic characters to differentiate *Z. borisovi* from *Z. protheroi*, are not preserved. However, the paracone fold on M3 is weak in ZSN-KKS-28-IPB as in *Z. borisovi*, and
<table><caption>TABLE 3. — Measurements (in mm) of the upper cheek teeth and skull of the amynodontid rhinocerotoid *Metamynodon planifrons* Scott & Osborn, 1887, UNISTRA.2015.0.1106. The width measurements of M1-3 are presented as follows: anterior/posterior orientation of the teeth. The measurements are in brackets when they are uncertain.</caption><thead><tr><th rowspan="2">Tooth</th><th colspan="2">Length</th><th colspan="2">Width</th><th colspan="2">Height</th></tr><tr><th>Left</th><th>Right</th><th>Left</th><th>Right</th><th>Left</th><th>Right</th></tr></thead><tbody><tr><td>P2</td><td>15.0</td><td>15.0</td><td>18.5</td><td>18.0</td><td>—</td><td>—</td></tr><tr><td>P3</td><td>17.0</td><td>19.0</td><td>27.5</td><td>29.0</td><td>—</td><td>—</td></tr><tr><td>P4</td><td>24.5</td><td>24.0</td><td>40.0</td><td>43.0</td><td>—</td><td>—</td></tr><tr><td>M1</td><td>35.5</td><td>33.5</td><td>56.5/48.0</td><td>56.0/50.0</td><td>—</td><td>—</td></tr><tr><td>M2</td><td>50.5</td><td>50.0</td><td>63.5/50.5</td><td>61.0/48.5</td><td>(15.0)</td><td>(14.0)</td></tr><tr><td>M3</td><td>60.0</td><td>60.5</td><td>55.0/32.5</td><td>55.5/33.0</td><td>(14.5)</td><td>(14.0)</td></tr><tr><td>Skull</td><td>—</td><td>—</td><td>—</td><td>—</td><td>—</td><td>—</td></tr><tr><td>Premaxilla<br>to orbit</td><td>160</td><td>—</td><td>—</td><td>—</td><td>—</td><td>—</td></tr><tr><td>Premaxilla<br>to occipital</td><td>555</td><td>—</td><td>—</td><td>—</td><td>—</td><td>—</td></tr></tbody></table>

contrary to *Z. protheroi* (Belyaeva 1971; Lucas *et al.* 1996; Lucas 2006), which is the only character that supports the assignment of this specimen to *Z. borisovi* in our phylogenetic analysis. Therefore, based on these anatomical comparisons of ZSN-KKS-28-IPB with Belyaeva (1971), Lucas *et al.* (1996) and Lucas (2006), ZSN-KKS-28-IPB can only be tentatively assigned to *Zaisanamynodon borisovi*.

Moreover, two species of Amynodontidae, *Cadurcodon ardynensis* (Osborn, 1923) and *Zaisanamynodon borisovi* are known from the Zaysan basin in north-west Kazakhstan (Lucas & Emry 1996; Emry *et al.* 1998). *Cadurcodon ardynensis* is known from the Kusto Svita at Kiin Kerish and from the Buran Svita at Kalmakpay Mountain (Lucas & Emry 1996; Emry *et al.* 1998). The presence of a third loph on P4 excludes an attribution of ZSN-KKS-28-IPB to *Cadurcodon*. The holotype of *Zaisanamynodon borisovi* (ANPIN 2761/1-22; Belyaeva, 1971) and ZSN-KKS-28-IPB both come from the Lower Aksyir Svita at Kiin Kerish. Thus, this supports our identification of ZSN-KKS-28-IPB as *Zaisanamynodon borisovi*.

Tribe *METAMYNODONTINI* Kretzoi, 1942

Genus *Metamynodon* Scott & Osborn, 1887

*Metamynodon* Scott & Osborn, 1887: 165.

TYPE SPECIES. — *Metamynodon planifrons* Scott & Osborn, 1887.

INCLUDED SPECIES. — According to literature *Metamynodon chadronensis* Wood, 1937, *Metamynodon mckinneyi* Wilson & Schiebout, 1981 are included in *Metamynodon*. However, some revision work of both species seems to be needed to assess their validity. Indeed, diagnostic characters used to describe *M. chadronensis* Wood, 1937 and *M. mckinneyi* Wilson & Schiebout, 1981 are not specific enough to distinguish them from the type species.

EMENDED DIAGNOSIS. — Within *Metamynodontini*, *Metamynodon* differs from other genera (*Paramynodon* Matthew, 1829, *Megalamynodon* Wood, 1945, and *Sellamynodon* Tissier, Becker, Codrea, Costeur, Fărcaş, Solomon, Venczel & Maridet, 2018) in having large and tusk-like canines, high-crowned cheek teeth, the

labially confluent trigonid and talonid, the premaxilla and the nasal reduced but still contacting each other along the border of external nares, a very large and massive zygomatic arch, a massive lower jaw (Wall 1989). *Metamynodon* differs from *Sellamynodon* in having a high zygomatic arch, a flat dorsal profile of the skull, the presence of a sagittal crest, a circular magnum foramen and m3 talonid equal or smaller than trigonid. *Metamynodon* differs from *Megalamynodon* in having a well-developed paroccipital process and strong upper canines. *Metamynodon* differs from *Paramynodon* in having a protoloph on P2, an upper postcanine diastema shorter than the length of upper premolars and the orbit positioned higher on the skull.

REMARK

Diagnosis same as for the type species.

*Metamynodon planifrons* Scott & Osborn, 1887
(Figs 5; 6; Table 3)

*Metamynodon rex* Troxell, 1921: 24.

*Metamynodon planifrons* — Scott & Osborn 1887: 165.

TYPE MATERIAL. — **Holotype.** VPM-9157, skull and anterior part of the left mandible (Scott & Osborn 1887; see online the database of the Zoological Collections of the Museum of Comparative Zoology - Harvard University).

REFERRED MATERIAL. — UNISTRA.2015.0.1106, skull with right C1 and P2-M3.

TYPE LOCALITY AND HORIZON. — Big Badlands, South Dakota, United States. White River Group, Brule Formation, early Oligocene (Scott & Osborn 1887; Scott 1941; Benton *et al.* 2015).

DESCRIPTION

Skull

The skull UNISTRA.2015.0.1106 is incomplete (Fig. 5). The anterior surface of the nasal is damaged and its extremity lacking. The right orbit is filled with matrix. The skull is brachycephalic (sensu Antoine 2002), with a maximum zygomatic width/nasal-occipital length ratio >0.50. The preorbital region constitutes less than 30% of the skull. There are no rugosities suggesting the presence of a horn.

In lateral view (Fig. 5A, B), the dorsal profile of the skull is flat. The tooth row extends beyond the middle of the skull. The premaxilla and the nasal contact each over along the border of external nares. The nasal incision is in front of the P2. The nasal, frontal and maxilla contact each other. There is a reduced and deep preorbital fossa. The anterior border of the orbit is above P4-M1. The orbit is relatively high on the skull. The anterior base of the zygomatic process of the maxilla is low. The position of the zygomatic arch on the skull is high. On the squamosal, a posterior groove on the zygomatic process is present. Both squamosal and frontal have a postorbital process. The squamosal area between the temporal and nuchal crests is flat. The external acoustic pseudomeatus is closed. The posterior margin of the pterygoid is nearly horizontal. The occipital side inclines posteriorly. A poorly developed nuchal tubercle (or occipital protuberance) on the occipital is present.
<figure><img src="image_11.png" /><figcaption>FIG. 5. — Skull of the amynodontid rhinocerotoid *Metamynodon planifrons* Scott & Osborn, 1887, UNISTRA.2015.0.1106, Big Badlands, South Dakota, United States, early Oligocene: **A**, right lateral view; **B**, three-dimensional model, right lateral view; **C**, dorsal view; **D**, three-dimensional model, dorsal view; **E**, ventral view; **F**, three-dimensional model, ventral view; **G**, occipital view; **H**, three-dimensional model, occipital view. Abbreviations: *eap*, external auditory pseudomeatus; *fm*, foramen magnum; *j*, jugal; *mx*, maxilla; *na*, nasal; *nc*, nuchal crest; *o*, orbit; *oc*, occipital condyle; *pgp*, postglenoid process; *pm*, premaxilla; *pocp*, paraoccipital process; *pof*, postorbital fossa; *popf*, postorbital process of the frontal; *popsq*, postorbital process of the squamosal; *pt*, pterygoid; *ptp*, posttympanic process; *sc*, sagittal crest; *sq*, squamosal; *vm*, vomer; *za*, zygomatic arch. Scale bar: 10 cm.</figcaption></figure>

In dorsal view (Fig. 5C, D), the zygomatic arches are wide and massive. The zygomatic index (maximum width at the zygomatic/maximum width at the frontals) is 1.55 (sensu Antoine 2002). The sagittal crest is strong. The external occipital protuberance is straight.

In ventral view (Fig. 5E, F), the zygomatic arches are complete and diverge abruptly from the maxilla. It starts above the M2 and separates above the M3. The vomer is acute. The post-glenoid apophysis (= process) is flat. The posttympanic process is fused to the postglenoid process. The posttympanic
A

<figure><img src="image_12.png" /></figure>

Quadratic M3

B

<figure><img src="image_13.png" /></figure>

C

<figure><img src="image_14.png" /></figure>

D

<figure><img src="image_15.png" /></figure>

FIG. 6. — Upper cheek teeth of the amynodontid rhinocerotoid *Metamynodon planifrons* Scott & Osborn, 1887, UNISTRA.2015.0.1106, Big Badlands, South Dakota, United States, early Oligocene: **A**, close-up of the right cheek teeth series, P2-M3, occlusal view; **B-D**, close-up of the right cheek teeth series, P2-M3, three-dimensional model, occlusal (**B**), lateral (**C**) and lingual views (**D**). Scale bar: 2 cm.

process is poorly developed but the paroccipital process is
developed and fused together.

In occipital view (Fig. 5G, H), the foramen magnum is circular.

The dental formula is I 3/?; C 1/?; P 3/?; M 3/. The alveoli of the incisors and the left canine can be observed in occlusal view. The right canine is in place, strong and cylindrical. The diastema between the canines and premolars is short. The series of premolars and molars are complete but worn. The premolar series are very short compared to the molar series (sensu Antoine 2002), with a LP3-4/LM1-3 ratio ≤0.42. There is no crochet and no antecrochet on the upper cheek teeth.

*Upper cheek teeth (Fig. 6)*

The P3 is submolariform and the P4 is semimolariform (sensu Heissig 1969). The protocone and hypocone are connected by a lingual bridge. The premolars have no labial cingulum, and their lingual cingulum is continuous. The postfossette is wide. The metaloph is transverse. On P2, the protoloph is present and does not join to the ectoloph. The hypocone and protocone of P2 are fused. On P3-4, the protoloph is fused to the ectoloph. The hypocone and the metacone are linked. The P4 has a crista.

The upper molars have a π form (Fig. 6A). They have neither lingual nor labial cingula. There is no constriction of the protocone. The parastyle is reduced. There is no crista and cristella. On M1-2, the protocone and hypocone are fused. There is no paracone fold. The metaloph is continuous and long, the metacone fold is absent. The metastyle is short. The posterior part of the ectoloph is straight. The M3 has quadrangular shape. The protoloph is transverse, the ectoloph and metaloph are distinct. The paracone fold is weak. The metastyle is directed posterolingually.

*Body mass*

The body mass of UNISTRA.2015.0.1106 was estimated to
be around 1.3 and 1.2 tons with the regression equations for

the Rhinocerotidae and all Ungulates respectively (Fortelius &
Kappelman 1993). They are based on several measurements,
including M2 and M3 lengths, basicondylar length, or zygo-
matic width (Table 3; Appendix 3).

Our estimations are lower than those of Averianov *et al.* (2016) for *Metamynodon planifrons* (c. “1794 kg”, see Averianov *et al.* (2016): supplemental table 2) based on the occlusal surface of m1, with the regression equation for generalized ungulates of Legendre (1989). This method can’t be applied to UNISTRA.2015.0.1106 because it is a skull, without mandible. As a comparison, similar results to ours were obtained estimating the body mass of VPM-9157 (Scott & Osborn (1887); holotype of *M. planifrons*), with the same equation, based on M3 length, basicondylar length, and zygomatic width (Table 3; Appendix 3). The body mass of VPM-9157 was estimated to be around 1.5 and 1.3 tons with the regression equations for the Rhinocerotidae and all Ungulates respectively (Fortelius & Kappelman 1993).

Despite this, our results are certainly over-estimated because
the same problems with these methods explained earlier for
*Zaysanamynodon* also apply to this genus (i.e., M2 and M3
much larger than all other cheek teeth in Amynodontidae,
and retention of a metastyle on M3).

REMARKS

UNISTRA.2015.0.1106 can be referred to Rhinoceroidea
based on the π-shape form of upper molars (Wall 1989). An
attribution of UNISTRA.2015.0.1106 to Amynodontidae
is reliable based on the reduced upper dental formula, with
the absence of P1, which is a derived character typical of
Amynodontidae (Wall 1989; Tissier et al. 2018). UNIS-
TRA.2015.0.1106 shares other diagnostic characters of the
Amynodontidae: the absence of the crochet, antecrochet
and crista; the reduced parastyle on the upper molars; the
quadratic M3 with a large metastyle; the absence of horn;
the presence of a preorbital fossa and a large sagittal crest
(Wall 1989; Tissier *et al.* 2018). Therefore, an attribution to Rhinocerotidae, Eggysodontidae, “Hyracodontidae” or Paraceratheriidae can be excluded.

UNISTRA.2015.0.1106 shares diagnostic characters of the Metamynodontini: the presence of the frontal-maxilla contact, a brachycephalic skull, an orbit positioned high on the skull, a reduced preorbital fossa and a wide, massive zygomatic arch (Wall 1989).

Within Metamynodontini, UNISTRA.2015.0.1106 differs from *Sellamynodon* in having: a high zygomatic arch; a flat dorsal profile of the skull; the presence of a sagittal crest; a circular foramen magnum. UNISTRA.2015.0.1106 differs from *Megalamynodon* in having a well-developed paroccipital process. UNISTRA.2015.0.1106 differs from *Paramynodon* in having a protoloph on P2, an upper postcanine diastema shorter than the length of the upper premolars and the orbit positioned higher on the skull. UNISTRA.2015.0.1106 can be referred to *Metamynodon* by the presence of large and tusk-like canines, the premaxilla and the nasal reduced but still contact each other along border of external nares, a very large and massive zygomatic arch (Wall 1989).

Three species of *Metamynodon* are considered as valid: *Metamynodon chadronensis*, *Metamynodon mckinneyi* and *Metamynodon planifrons*. *Metamynodon chadronensis* is known from fragmented skulls, mandibles, and isolated teeth (Wood 1937; Wilson & Schiebout 1981). *Metamynodon mckinneyi* is only known from a mandible while our new material UNISTRA.2015.0.1106 to identify is a skull, so no direct comparison was possible. The holotype of *M. chadronensis* is also a lower jaw, but some incomplete skulls have been attributed to this species by Wilson & Schiebout (1981). These identifications are mostly based on dental measurements of the lower jaw, which are smaller than *M. planifrons*. However, the dimensions of the upper teeth do not really reflect this smaller dimension and sometimes fit within the observed range of measurements of *M. planifrons* (see Wilson & Schiebout 1981: table 14). Thus, in the absence of a lower jaw and of a clearer distinction between *M. chadronensis* and *M. planifrons*, we refer our specimen to *M. planifrons*, the type species of the genus, as primarily identified by Wood, in Gillet (1960). Furthermore, in our phylogenetic analysis UNISTRA.2015.0.1106 also shares with *M. planifrons* “a low anterior base of the zygomatic process of maxilla”; “an acute vomer”; and “a weak paracone fold on M3”.

## RESULTS

Only one most parsimonious tree of 805 steps (CI = 0.3938; RI = 0.4906) was obtained by using the traditional search of TNT version 1.5 (Fig. 7). The same result was also found with the heuristic search of PAUP* version 4.0a167. The complete list of transformations was obtained with the “tree description” command of PAUP* version 4.0a167 (Appendices 4; 5).

Results concerning the phylogenetic relationships within and between the families of Rhinocerotoidea show a similar topology as Tissier *et al.* (2018), from which we used the

matrix. Rhinocerotidae, Eggysodontidae, Paraceratheriidae and Amynodontidae form monophyletic groups.

### RHINOCEROTIDAE

The monophyly of Rhinocerotidae, including *Trigonias osborni* Lucas, 1900, *Aceratherium incisivum* Kaup, 1832 and *Ronzotherium filholi* (Osborn, 1936), is supported by eleven unambiguous synapomorphies: presence of a sagittal crest on the basilar process 44 (1); i2 is tusk-like 79 (1); i3 is absent 81 (1); c1 is absent 82 (1); p2 paralophid is isolated, spur-like 154 (0); semilunate distal border of anterior side is acute 212 (0); magnum posterior tuberosity is long 220 (1); unciform posterior expansion of the pyramidal-facet is usually absent 223 (1); astragalus (Transverse Diameter/Height) ratio = 1 < TD/H < 1.2 252 (1); astragalus (Antero-Posterior Diameter/Height) ratio = 0.65 253 (1); proximal border of the anterior side of the metacarpal III is straight 271 (0). The clade is weakly supported (Bremer index = 1). The species *Hyrachyus eximius* Leidy, 1871 is placed as the sister taxon of the Rhinocerotidae.

### “HYRACODONTIDAE”

*Teletaceras radinskyi* Hanson, 1989 is placed as an early-diverging rhinocerotoid and as a sister taxon to the clade including the Eggysodontidae, the Paraceratheriidae and the Amynodontidae. The monophyly of Eggysodontidae is supported by five unambiguous synapomorphies: protocone and hypocone on P2 form a lingual bridge 94 (1); the hypocone is anterior to metacone on P3-4 103 (2); M3 ectoloph and metaloph are fused (ectometaloph) 133 (1); navicular cross section is rectangle 268 (1); lower canines are strong 284 (2). The clade has a Bremer index = 2. Eggysodontidae are sister group of the clade formed by *Hyracodon nebraskensis* Leidy, 1850, Paraceratheriidae and Amynodontidae. *Hyracodon nebraskensis* is a sister taxon to Paraceratheriidae and Amynodontidae. Three unambiguous synapomorphies support the monophyly of Paraceratheriidae: nearly horizontal symphysis 53 (2); M3 ectoloph and metaloph are fused (ectometaloph) 133 (1); atlas axis-facets are transversally concave 187 (2) and it is weakly supported (Bremer index = 1).

### AMYNODONTIDAE

“*Pappaceras*” *meiomenus* Wang H.-B., Bai, Meng & Wang Y.-Q., 2016 shares with Amynodontidae seven unambiguous synapomorphies: compared length of the premolar/molar rows < 42 63 (2); P1 in adults is usually present 91 (1); P2 protocone and hypocone are fused 94 (0); P3-4 protocone and hypocone are fused 102 (0); upper molars antecrochet is usually absent 110 (1); upper molars lingual cingulum is usually present 114 (1); M1-2 paracone fold is strong 118 (0).

The monophyly of the Amynodontidae is well supported, with a Bremer index of 4. The monophyly of Amynodontidae (here the smallest clade including *Rostriamynodon grangeri* Wall & Manning, 1986 and *Cadurcodon kazakademius* Biryukov, 1961) is defined by five unambiguous synapomorphies: lacrimal process is absent 8 (1); anterior base of the zygomatic process of the maxilla is high 10 (0); P1 in adults is always absent 91 (2); upper canine is strong 283 (2); upper molars parastyle is reduced 296 (1).
<figure><img src="image_16.png" /><figcaption>FIG. 7. — Single parsimonious tree of Amynodontidae Scott & Osborn, 1883 within Rhinocerotoidea Owen, 1845, with *Tapirus terrestris* (Linnaeus, 1758) and *Hyrachyus eximius* Leidy, 1871 considered as outgroups. Tree length = 806; CI = 0.3933; RI = 0.4912. Numbers at nodes are Bremer support values, **numbers in red** indicate bootstrap values, when greater than 50%. Taxa ages are based on literature as detailed in Table 1. Geological time scale was produced with TSCreator (Ogg 2020).</figcaption></figure>

## METAMYNODONTINI

The tribe Metamynodontini is defined by three unambiguous synapomorphies free of homoplasy (Bremer index = 1): the zygomatic arch is high 11 (1); the postglenoid process of squamosal is flat 42 (0); the humerus distal articulation has a deep median constriction (diabolo-shaped) 194 (1). This tribe includes the two clades (*Paramynodon*, *Megalamynodon*) and (*Sellamynodon*, *Metamynodon*).

The clade formed by *Paramynodon* and *Megalamynodon* is supported by two unambiguous synapomorphies (Bremer

index = 1): the zygomatic process progressively diverges from the maxilla 37 (0); I3 has a similar size to I2 293 (1). The clade formed by *Sellamynodon* and *Metamynodon* is supported by a single unambiguous synapomorphy (Bremer index = 1): the external auditory pseudomeatus is closed 18 (2). The specimen UNISTRA.2015.0.1106 is sister group to *Metamynodon planifrons*, which supports its taxonomical identification (Bremer index = 1). *Metamynodon planifrons* (*sensu lato*, = UNISTRA.2015.0.1106 and *M. planifrons*) has three autapomorphies: the anterior base of the zygomatic process
of the maxilla is low 10 (1); the vomer is acute 38 (0); the paracone fold of M3 is absent 289 (1).

## CADURCODONTINI

The tribe Cadurcodontini includes *Zaisanamynodon*, *Amynodontopsis*, *Cadurcotherium* and *Cadurcodon*. This clade is defined by five unambiguous synapomorphies (Bremer index = 1): the postglenoid process of squamosal is dihedron 42 (2); the upper premolars labial cingulum is always present 83 (0); the olecranon fossa of the humerus is low 193 (1); the mandibular condylar process is high 287 (0); the talonid of m3 is longer than the trigonid 288 (1).

*Zaisanamynodon* is placed as a sister group of the clade formed by *Amynodontopsis*, *Cadurcotherium* and *Cadurcodon*. The monophyly of *Zaisanamynodon* is supported by three synapomorphies (Bremer index = 1): the zygomatic process progressively diverges from the maxilla 37 (0); the lingual cingulum of the upper molars is usually absent 114 (2); the third posterior loph is present on P4 298 (1). ZSN-KKS-28-IPB is a sister group of *Zaisanamynodon borisovi*, which supports its identification (Bremer index = 1). *Zaisanamynodon borisovi* (*sensu lato*, = ZSN-KKS-28-IPB and *Z. borisovi*) differs from *Zaisanamynodon protheroi* by a single autapomorphy: the paracone fold of M3 is weak 289 (1). *Zaisanamynodon protheroi* is defined by only one unambiguous autapomorphy: the lingual cingulum of the lower premolars is reduced 148 (0), but five other ambiguous autapomorphies might support the distinction of the two species.

*Cadurcotherium* and *Amynodontopsis* form a clade supported by three unambiguous synapomorphies (Bremer index = 1): the rostral end of the nasal bones is narrow 24 (0); the mandibular ramus is inclined posteriorly 60 (0); the labial cingulum of the lower molars is always absent 159 (3). *Amynodontopsis* is sister group to *Cadurcotherium*, and they share three synapomorphies (Bremer index = 2): the zygomatic process progressively diverges from the maxilla 37 (0); the presence of a sagittal crest on the basilar process 44 (1); the M3 paracone fold is weak 289 (1). *Amynodontopsis jiyuanensis* has six autapomorphies: nasal notch is above P1-3 3 (0); nasal bones are long 26 (0); paraoccipital process of the occipital is little developed 48 (1); upper molars antecrochet is usually present 110 (2); M1-2 metastyle is long 120 (1); M1-2 posterior part of the ectoloph is concave 122 (1). *Cadurcotherium* is supported by two synapomorphies (Bremer index = 2): the upper molars lingual cingulum is always absent 114 (3); the lower molars hypolophid is almost sagittal 161 (2). *Cadurcotherium cayluxi* is defined by two autapomorphies: the M1 postfossette is present 127 (0); the m3 talonid is equal or smaller than trigonid 288 (0). *Cadurcotherium minum* is defined by one autapomorphy: upper premolars labial cingulum is always absent 83 (3).

*Cadurcodon* is placed as a sister group to the clade formed by *Cadurcotherium* and *Amynodontopsis*. *Cadurcodon* is supported by six unambiguous synapomorphies (Bremer index = 2): the ramus coronoid process is little developed 61 (1); the I1 is absent 71 (1); the i1 is absent 76 (1); the upper molars antecrochet is usually absent 110 (1); the upper

postcanine diastema is short 291 (1); the I3 size is distinctly smaller to I2 293 (2).

## DISCUSSION

### PHYLOGENETIC RELATIONSHIPS

Our results differ strongly from those obtained by the two analyses of Bai *et al.* (2020) in the arrangement of the branches of the different families. Here, and as in Wang *et al.* (2016, 2018) Paraceratheriidae are sister group of the Amynodontidae, whereas in both analyses (parsimony and Bayesian) of Bai *et al.* (2020), they are sister group of the Rhinocerotidae. Besides, in our analysis, Rhinocerotidae (+ *Hyrachyus*) are part of a basal trichotomy, which differs from the results of Wang *et al.* (2016, 2018). Furthermore, according to Bai *et al.* (2020), *Hyrachyus* could be considered as the earliest-branching representative of Rhinoceroidea *sensu stricto*, whereas in our results it is placed as sister-group to the Rhinocerotidae.

These differences could obviously be explained by the widely different taxonomic sampling of the analyses, which is centered on Amynodontidae in our case, but on early Ceratomorpha Wood, 1937 for Bai *et al.* (2020), as well as by the nature of the two matrices. Indeed, the morphological matrix from Bai *et al.* (2020) only includes cranial and dental characters (which are more commonly preserved in early Ceratomorpha), whereas ours includes numerous postcranial characters as well, thus possibly leading to the expression of a different evolutionary signal. For example, the clade formed by *Hyrachyus* and Rhinocerotidae is supported by seven unambiguous synapomorphies, three of which are postcranial characters. Likewise, the Paraceratheriidae are united with the Amynodontidae based on seven unambiguous synapomorphies, which also include three postcranial characters. Thus, we believe that future analyses that will combine both a large-scale taxonomic sampling, as in Bai *et al.* (2020), and the inclusion of postcranial characters might resolve some of the inconsistencies observed in these different results, which was also suggested by these authors.

The group, composed of Eggyodontidae, *Hyracodon nebraskensis*, Paraceratheriidae which formerly formed the family "Hyracodontidae" (now considered as paraphyletic; Wang *et al.* 2016; Tissier *et al.* 2018), remains paraphyletic in our study (Fig. 7). Some differences can be observed with the tree obtained by the previous analysis of Tissier *et al.* 2018: *Teletaceras radinskyi* is here less derived and closer to the Rhinocerotidae (in fact it should belong to this family, based on the phylogeny of Tissier *et al.* 2020, however, the rhinocerotid sampling is too small to branch it within this group) whereas *Hyracodon nebraskensis* is now no more a sister group of the Paraceratheriidae, but slightly more basal (Fig. 7). This may be caused by the different taxonomic sampling.

"Pappaceras" *meiomenus*, had been referred to the family Paraceratheriidae by Wang *et al.* (2016). Our result shows that "P." *meiomenus* and Paraceratheriidae do not form a monophyletic group (Fig. 7) and that "P." *meiomenus* is closer to the Amynodontidae, as already proposed by Tissier *et al.* (2018).
The topology of Amynodontidae is congruent with that of Tissier *et al.* (2018), even though our taxonomic sampling is slightly different. Two main clades, Metamynodontini and Cadurcodontini, were recovered (Fig. 7). Metamynodontini are described by Averianov *et al.* (2016) as “the taxon that includes *Metamynodon planifrons* and all the amynodonts that are closer to it than to *Cadurcodon ardynensis*.”. In reverse, they define Cadurcodontini as “the taxon that includes *Cadurcodon ardynensis* and all amynodonts that are closer to it than to *Metamynodon planifrons*”. Thus, considering the cladistic results and contrary to what Wall (1980, 1989) had suggested, *Zaisanamynodon* – originally placed in the tribe of Metamynodontini – should belong to the Cadurcodontini instead (Fig. 7). The cladistic analysis of Averianov *et al.* (2016) had already suggested this but did not retrieve the monophyly of the genus. The phylogenetic position of *Zaisanamynodon* and the monophyly of the genus had already been recovered by Tissier *et al.* (2018). The incorporation in the matrix of ZSN-KKS-28-IPB – referred to *Z. borisovi* – supports even further the position of this genus within the Cadurcodontini (Fig. 7).

Tissier *et al.* (2018) showed that *Amynodontopsis* belongs to the Cadurcodontini while Averianov *et al.* (2016) had suggested a more basal position for it. The incorporation into the analysis of the recently described *Amynodontopsis jiyuanensis* supports a position of the genus within the Cadurcodontini (Fig. 7). However, Wang *et al.* (2020) had also suggested that *Amynodontopsis* aff. *bodei* Tissier, Becker, Codrea, Costeur, Fărcaş, Solomon, Venczel & Maridet, 2018 from Romania and Hungary might not belong to this genus, but we did not include it our taxonomical sampling, due to its incompleteness. As suggested by Wang *et al.* (2020), the specimens referred to it need to be reexamined, considering the discovery of this new species from China.

The incorporation of UNISTRA.2015.0.1106 into the matrix also resolves the generic/specific relationships within the Metamynodontini (Fig. 7). Averianov *et al.* (2016) had not resolved the generic/specific relationships within the Metamynodontini while Tissier *et al.* (2018) suggested that *Paramynodon birmanicus* (Pilgrim & Cotter, 2016) and *Megalamynodon regalis* Scott, 1945 were early-diverging genera of Metamynodontini and that *Sellamynodon zimborensis* (Codrea & Suraru, 1989) and *Metamynodon planifrons* formed a derived clade. Here, we found that (*Paramynodon birmanicus*, *Megalamynodon regalis*) and (*Sellamynodon zimborensis*, *Metamynodon planifrons*) form two sister clades.

## CRANIAL ANATOMY OF THE CADURCODONTINI AND METAMYNODONTINI

Wall (1980) has already shown evidence for a proboscis in Amynodontidae. This structure appeared in Cadurcodontini and would have had the function of locating and manipulating food, reminding the proboscis of tapirs (Wall 1980). *Cadurcodon* presents the greatest number of cranial specializations likely to be associated with the presence of a proboscis (Wall 1980). Following this hypothesis, *Amynodontopsis* also had a well-developed proboscis but less extreme than *Cadurcodon* (Wall 1980). *Cadurcotherium* and *Zaisanamynodon* share with

the Cadurcodontini cranial characters suggesting the position, the movement, and the musculature required for the presence of a proboscis, notably, “the well-developed preorbital fossa” or “the reduction in length of the nasal and of the preorbital region” (Belyaeva 1971; Wall 1980; de Bonis 1995; Lucas *et al.* 1996; Lucas 2006; Ménouret 2018; Tissier *et al.* 2018). These characters are not as derived as in *Amynodontopsis-Cadurcodon*, but *Cadurcotherium-Zaisanamynodon* are much more similar in their skull morphology to Cadurcodontini than to Metamynodontini. The specialization of the facial region to the presence of a proboscis seems to appear gradually in Cadurcodontini, with *Cadurcodon* having the most derived characters. Wall (1980) indicates that *Tapirus* Brisson, 1762 and *Cadurcodon* have cranial similarities, associated with the presence of a proboscis. *Tapirus terrestris*, like the Cadurcodontini, has “the nasal bone length reduced and the nasal incision back of the P4-M1” (Antoine *et al.* 2010). For *Tapirus*, Antoine (2002) relates the elongation (backwards) of the nasal incision to the adaptation of the peri-nasal region to the presence of a proboscis. This also supports the similarities in structure and function of the proboscis between tapirs and Cadurcodontini.

Metamynodontini also show some characters that may suggest the presence of a proboscis: “reduction of the length of the nasal” in *Paramynodon* and *Metamynodon* (Scott & Osborn 1887; Colbert 1938; Scott 1941; see UNISTRA.2015.0.1106), the “maxilla-frontal contact” is present in *Metamynodon* (Scott & Osborn 1887) and “the length of the preorbital region” is reduced in *Metamynodon*, while it is longer in *Paramynodon* (Scott & Osborn 1887; Colbert 1938; Wall 1980). However, “the limit of the nasal incision” is in front of the upper premolars and the preorbital fossa is much less developed in *Paramynodon* and *Metamynodon* than in Cadurcodontini (Colbert 1938; Wall 1980; see UNISTRA.2015.0.1106). These characters, therefore, do not constitute a specialization of the facial region to the presence of a proboscis but rather the existence of a sort of prehensile upper lip in Metamynodontini (Wall 1980). This enlarged mobile lip would have been adapted to seize food, reminding the prehensile upper lip of the African black rhinoceros or the giraffe (Wall 1980).

This specialization of the skull into a proboscis would explain the divergence between the two tribes (Wall 1980). On the one hand, the conservation of an ancestral form of the skull of Amynodontidae by Metamynodontini (as in *Sharamynodon* Kretzoi, 1942). They would have been endowed of a prehensile upper lip rather than a proboscis. On the other hand, Cadurcodontini could have developed a specialization of the skull, the proboscis, related to foraging as in tapirs (Wall 1980).

## GEOGRAPHICAL DISTRIBUTION OF AMYNODONTIDAE

Amynodontidae are a family spanning the middle Eocene-Oligocene interval (Fig. 8; Appendix 6). They were highly diversified in the middle Eocene in Asia and North America, as well as in Eastern Europe, but did not appear in Western Europe until the early Oligocene (Wall 1989; Tissier *et al.* 2018).

The Metamynodontini and Cadurcodontini both have an Holarctic distribution, but *Amynodontopsis* and *Zai-
<figure><img src="image_17.png" /><figcaption>FIG. 8. — Temporal and geographical distribution maps of Amynodontidae Scott & Osborn, 1883 in Eurasia and North America: A, middle to late Eocene; B, Oligocene. See Appendix 6 for references of the occurrences.</figcaption></figure>

*sanamynodon* are the only two genera of Amynodontidae that are present both in Asia and North America. Tissier *et al.* (2018) had also reported an earliest occurrence of *Amynodontopsis* in Eastern Europe, with a suspected middle Eocene age, but its identification remains debated (Wang *et al.* 2020). However, the recent description of *Amynodontopsis jiyuanensis* documents a new early occurrence of the genus on the Asian landmass during the middle Eocene and shows that *Amynodontopsis* seems to have first emerged in Asia and later immigrated to North America (Wang *et al.* 2020). Conversely, *Zaisanamynodon* is present since the middle Eocene both in North America and Asia (Fig. 8).

*Metamynodon* is restricted to the North American landmass, from the middle Eocene to the early Oligocene (Fig. 8) whereas its sister-genus, *Sellamynodon*, is only documented in Eastern Europe, from a single locality (Tissier *et al.* 2018).

*Cadurcotherium* is mainly documented in Europe (mainly France) during the Oligocene (Fig. 8). Its presence in Western Europe after the Eocene-Oligocene transition would have been related to the “Grande Coupure” event described by Stehlin (1909). This biogeographic event is marked by a large

extinction of endemic Eocene mammals and the immigration of new taxa from Asia (Stehlin 1909) as the consequence of a climatic change related to the Oi-1 glaciation at the beginning of the Oligocene, involving a drop of the sea level (Legendre 1989; Zachos *et al.* 2001; Hooker *et al.* 2004). *Cadurcotherium* is recorded in South Asia throughout the Oligocene epoch, with *Cadurcotherium indicum*; Antoine *et al.* 2004; Métais *et al.* 2009).

## CONCLUSION

The inclusion in the matrix of the new material ZSN-KKS-28-IPB (*Zaisanamynodon borisovii*), UNISTRA.2015.0.1106 (*Metamynodon planifrons*) and *Amynodontopsis jiyuanensis*, but also the revised coding of two species assigned to *Cadurcotherium* provide a more exhaustive sampling compared to the previous phylogenetic analyses of Amynodontidae. The obtained cladogram gives a new and more solid phylogenetic hypothesis, especially in distinguishing two main tribes Cadurcodontini and Metamynodontini. However, a revision
of "Pappaceras" *meiomenus* would be necessary to determine
its position as basal or sister taxon of Amynodontidae. The
future study of postcranial material of Amynodontidae, which
remains greatly understudied, could improve our understand-
ing of the relationships between Amynodontidae taxa as well
as further their relationship within Rhinoceroidea. The
ecology of the family is also very poorly known. Analyses on
long bones could permit to understand morphological and
anatomical bone adaptations to an aquatic lifestyle, notably
for several species suspected of semi-aquatic habits.

Acknowledgements

We sincerely thank Kévin Janneau (“Jardin des sciences de l’Université de Strasbourg”/“Collections de l’École et Observatoire des Sciences de la Terre de Strasbourg, Université de Strasbourg”, France), Olivier Maridet (JURASSICA Museum, Switzerland), Prof. David Lordkipanidze and Prof. Vyacheslav Chkhikvadze† (Georgian National Museum, Georgia) for having provided access to the collections. We are grateful to Olivier Maridet and Jérémy Anquetin (JURASSICA Museum, Switzerland) for valuable help and discussion. We also thank Pierre-Olivier Antoine and two other anonymous reviewers, as well as the editors and staff, at *Comptes Rendus Palevol*, Michel Laurin, Adenise Lopes, Audrina Neveu, Lorenzo Rook, for their very helpful comments on the early version of the manuscript. This project was financially supported by the Swiss National Science Foundation (SNF projects 200021_162359 and P2FRP2_199605).

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Submitted on 2 February 2021;
accepted on 27 January 2022;
published on 20 March 2023.
APPENDICES

APPENDIX 1. — The following appendix is the matrix used to compute the phylogeagenetic analysis. The matrix consists of 32 terminals scored across 298 anatomical characters. A version of the data matrix executable in Mesquite/PAUP* (.nexus) and the same version executable in TNT (.tnt): https://doi.org/10.5852/cr-palevol2023v22a8_s1

APPENDIX 2. — The following appendix is the detailed list of the 298 characters used to score the 32 terminals considered in the cladistic analysis. The characters 1-282 are from the sequence of Antoine (2002), including the characters 36, 60, 103 and 140 modified from the original sequence to form morphoclines by Tissier et al. (2018). The characters 283-289 are from Tissier et al. (2018). The characters 290-297 are based on the characters 8, 9, 16, 23, 25, 39, 41 and 45 of Averianov et al. (2016). The character 298 is newly included here.

1 Nasal: lateral apophysis = 0, absent; 1, present

2 Maxillary: foramen infraorbitalis = 0 above premolars; 1, above molars

3 Nasal incision = 0, above P1-3; 1, above P4-M1

4 Nasal septum = 0, never ossified; 1, ossified (even sometimes)

5 Nasal septum: ossified = 0, partial; 1, complete

6 Nasal/lacrymal: contact = 0, long; 1, punctual or absent

7 Orbit: anterior border = 0, above P4-M2; 1, above M3; 2, behind M3

8 Lacrymal: lacrymal process = 0, present; 1, absent

9 Frontal: processus postorbitalis = 0, present; 1, absent

10 Maxilla: anterior base of the zygomatic process = 0, high; 1, low

11 Zygomatic arch = 0, low; 1, high; 2, very high

12 Zygomatic arch: processus postorbitalis = 0, present; 1, absent

13 Zygomatic arch: processus postorbitalis = 0, on jugal; 1, on squamosal

14 Jugal/squamosal: suture = 0, smooth; 1, rough

15 Skull: dorsal profile = 0, flat; 1, concave; 2, very concave

16 Sphenoid: foramen sphenorbitale and f. rotundum = 0, distinct; 1, fused

17 Squamosal: area between temporal and nuchal crests = 0, flat; 1, depression

18 External auditory pseudomeatus = 0, open; 1, partially closed; 2, closed

19 Occipital side = 0, inclined forward; 1, vertical; 2, inclined backward

20 Occipital: nuchal tubercle = 0, little developed; 1, developed; 2, very developed

21 Skull: back of teeth row = 0, in the posterior half; 1, restricted to the anterior half

22 Pterygoid: posterior margin = 0 nearly horizontal; 1, nearly vertical

23 Skull = 0, dolichocephalic (I/L × 100 < 50); 1, brachycephalic (I/L × 100 > 50)

24 Nasal bones: rostral end = 0, narrow; 1, broad; 2, very broad

25 Nasal bones = 0, totally separated; 1, anteriorly separated; 2, fused

26 Nasal bones = 0, long; 1, short; 2, very long

27 Median nasal horn = 0, absent; 1, present

28 Median nasal horn = 0, small; 1, developed

29 Paired nasal horns = 0, absent; 1, present

30 Paired nasal horns = 0, terminal bumps; 1, lateral crests

31 Frontal horn = 0, absent; 1, present

32 Frontal horn = 0, small; 1, huge

33 Orbit: lateral projection = 0, absent; 1, present

34 Zygomatic width/frontal width = 0, less than 1.5; 1, more than 1.5

35 Frontal-parietal = 0, sagittal crest; 1, close frontoparietal crests; 2, distant crests

36 Occipital crest = 0, straight; 1, concave; 2, forked

37 Maxillary: processus zygomaticus maxillari, anterior tip = 0, progressive; 1, brutal

38 Vomer = 0, acute; 1, rounded

39 Squamosal: articular tubercle = 0, smooth; 1 high

40 Squamosal: transversal profile of articular tubercle = 0, straight; 1, concave

41 Squamosal: foramen postglenoidicum = 0, distant from the processus postglenoidalis; 1, close to it

42 Squamosal: processus postglenoidalis = 0, flat; 1, convex; 2, dihedron

43 Basioccipital: foramen nervi hypoglossi = 0, in the middle of the fossa; 1 shift anteroexternally

44 Basioccipital: sagittal crest on the basilar process = 0, absent; 1, present

45 Squamosal: posterior groove on the processus zygomaticus = 0, absent; 1, present

46 Squamosal-occipital: processus post-tympanicus and processus paraoccipitalis = 0, fused; 1, distant

47 Squamosal: processus post-tympanicus = 0, well developed; 1, little developed; 2, huge

48 Occipital: processus paraoccipitalis = 0, well developed; 1, little developed

49 Occipital: foramen magnum = 0, circular; 1, subtriangular

50 Basioccipital: median ridge on the condyle = 0, absent; 1, present

51 Basioccipital: medial truncation on the condyle = 0, absent; 1, present

52 Basioccipital: medial truncation on the condyle = 0, present at juvenile stage; 1, still present at adult stage

53 Symphysis = 0, very upraised; 1, upraised; 2, nearly horizontal

54 Symphysis = 0, spindly; 1, massive; 2, very massive

55 Symphysis: posterior margin = 0, in front of p2; 1, level of p2-4

56 Foramen mentale = 0, in front of p2; 1, level of p2-4

57 Corpus mandibulae: lingual groove = 0, present; 1, absent

58 Corpus mandibulae: lingual groove = 0, present even in adults; 1, only present in juveniles

59 Corpus mandibulae: base = 0, straight; 1, convex; 2, very convex

60 Ramus = 0, inclined backward; 1, vertical; 2, inclined forward

61 Ramus: processus coronoideus = 0, well developed; 1, little developed

62 Foramen mandibulare = 0, below the teeth neck; 1, above the teeth neck

63 Compared length of the premolars/molars rows = 0, I P/M > 50; 1, 42 < I P/M ≤ 50; 2, I PM ≤ 42

64 Cheek teeth: enamel foldings = 0, absent; 1, weak; 2, developed; 3, intense

65 Cheek teeth: cement = 0, absent; 1, present

66 Cheek teeth: cement = 0, weak or variable; 1, abundant

67 Cheek teeth: shape of enamel = 0, wrinkled; 1, wrinkled and corrugated; 2, corrugated and arborescent

68 Cheek teeth: crown = 0, low; 1, high

69 Cheek teeth: crown = 0, high; 1, partial hypsodonty; 2, subhypodonty; 3, hypsodonty
**70** Cheek teeth: roots = 0, distinct; 1, joined; 2, fused

**71** I1 = 0, present; 1, absent

**72** I1: shape of the crown (cross-section) = 0, almond; 1, oval; 2, halfmoon

**73** I2 = 0, present; 1, absent

**74** I3 = 0, present; 1, absent

**75** C1 = 0, present; 1, absent

**76** i1 = 0, present; 1, absent

**77** i1: crown = 0, developed, with a pronounced neck; 1, reduced

**78** i2 = 0, present; 1, absent

**79** i2: shape = 0, incisor-like; 1, tusk-like

**80** i2: orientation = 0, parallel; 1, divergent

**81** i3 = 0, present; 1, absent

**82** c1 = 0, present; 1, absent

**83** Upper premolars: labial cingulum = 0, always present; 1, usually present; 2, usually absent; 3, always absent

**84** P2-4: crochet = 0, always absent; 1, usually present; 2, always present

**85** P2-4: crochet = 0, always simple; 1, usually simple; 2, usually multiple

**86** P2-4: metaloph constriction = 0, absent; 1, present

**87** P2-4: lingual cingulum = 0, always present; 1, usually present; 2, usually absent; 3, always absent

**88** P2-4: lingual cingulum = 0, continuous; 1, reduced

**89** P2-4: postfossette = 0, narrow; 1, wide; 2, posterior wall

**90** P2-3: antecrochet = 0, always absent; 1, usually absent; 2, usually present; 3, always present

**91** P1 (in adults) = 0, always present; 1, usually present; 2, always absent

**92** P1: anterolingual cingulum = 0, present; 1, absent

**93** P2 = 0, present; 1, absent

**94** P2: protocone and hypocone = 0, fused; 1, lingual bridge; 2, separated; 3, lingual wall

**95** P2: metaloph = 0, hypocone posterior to metacone; 1, transverse; hypocone anterior to metacone

**96** P2: lingual groove = 0, present; 1, absent

**97** P2: protocone = 0, equal or stronger than the hypocone; 1, less strong than the hypocone

**98** P2: protoloph = 0, present; 1, absent

**99** P2: protoloph = 0, joined to the ectoloph; 1, interrupted

**100** P3-4: medifossette = 0, always absent; 1, usually absent; 2, usually present; 3, always present

**101** P3-4: constriction of the protocone = 0, always absent; 1, usually absent; 2, usually present; 3, always present

**102** P3-4: protocone and hypocone = 0, fused; 1, lingual bridge; 2, separated; 3, lingual wall

**103** P3-4: metaloph = 0, hypocone anterior to metacone; 1, transverse; 2, hypocone posterior to metacone

**104** P3: protoloph = 0, joined to the ectoloph; 1, interrupted

**105** P3: crista = 0, always absent; 1, usually absent; 2, usually present; 3, always present

**106** P3: pseudometaloph = 0, always absent; 1, sometimes present

**107** P4: antecrochet = 0, always absent; 1, usually absent; 2, usually present; 3, always present

**108** P4: hypocone and metacone = 0, joined; 1, separated

**109** Upper molars: labial cingulum = 0, always present; 1, usually present; 2, usually absent; 3, always absent

**110** Upper molars: antecrochet = 0, always absent; 1, usually absent; 2, usually present; 3, always present

**111** Upper molars: crochet = 0, always absent; 1, usually absent; 2, usually present; 3, always present

**112** Upper molars: crista = 0, always absent; 1, usually absent; 2, usually present; 3, always present

**113** Upper molars: medifossette = 0, always absent; 1, usually absent; 2, usually present

**114** Upper molars: lingual cingulum = 0, always present; 1, usually present; 2, usually absent; 3, always absent

**115** M1-2: constriction of the protocone = 0, always absent; 1, usually absent; 2, usually present; 3, always present

**116** M1-2: constriction of the protocone = 0, weak; 1, strong

**117** M1-2: paracone fold = 0, present; 1, absent

**118** M1-2: paracone fold = 0, strong; 1, weak

**119** M1-2: metacone fold = 0, present; 1, absent

**120** M1-2: metastyle = 0, short; 1, long

**121** M1-2: metaloph = 0, long; 1, short

**122** M1-2: posterior part of the ectoloph = 0, straight; 1, concave

**123** M1-2: cristella = 0, always absent; 1, usually present; 2, always present

**124** M1-2: posterior cingulum = 0, continuous; 1, low and reduced

**125** M1: metaloph = 0, continuous; 1, hypocone isolated

**126** M1: antecrochet-hypocone = 0, always separated; 1, sometimes joined; 2, always joined

**127** M1: postfossette = 0, present; 1, usually absent

**128** M2: protocone, lingual groove = 0, always absent; 1, usually absent; 2, always present

**129** M2: metaloph = 0, continuous; 1, hypocone isolated

**130** M2: mesostyle = 0, absent; 1, present

**131** M2: mesostyle = 0, weak; 1, strong

**132** M2: antecrochet and hypocone = 0, separated; 1, joined

**133** M3: ectoloph and metaloph = 0, distinct; 1, fused (ectometaloph)

**134** M3: shape = 0, quadrangular; 1, triangular

**135** M3: constriction of the protocone = 0, always absent; 1, usually absent; 2, always present

**136** M3: protocone = 0, trefoil-shape; 1, indented

**137** M3: protoloph = 0, transverse; 1, lingually elongated

**138** M3: posterior groove on the ectometaloph = 0, present; 1, absent

**139** P2-3: vertical external roughnesses = 0, absent; 1, present

**140** Lower cheek teeth: ectolophid groove = 0, smooth; 1, developed, U-shaped; 2, angular, V-shaped

**141** Lower cheek teeth: ectolophid groove = 0, vanishing before the neck; 1, developed until the neck

**142** Lower cheek teeth: trigonid = 0, angular; 1, rounded

**143** Lower cheek teeth: trigonid = 0, obtuse or right dihedron; 1, acute dihedron

**144** Lower cheek teeth: metaconid = 0, joined to the metalophid; 1, constricted

**145** Lower cheek teeth: entoconid = 0, joined to the hypolophid; 1, constricted

**146** Lower premolars: lingual opening of the posterior valley = 0, U-shape; 1, narrow, V-shape

**147** Lower premolars: lingual cingulum = 0, always present; 1, usually present; 2, usually absent; 3, always absent

**148** Lower premolars: lingual cingulum = 0, reduced; 1, continuous
APPENDIX 2. — Continuation.

149 Lower premolars: labial cingulum = 0, present; 1, absent

150 Lower premolars: labial cingulum = 0, continuous; 1, reduced

151 d1/p1 (in adults) = 0, always present; 1, usually present; 2, usu-
ally absent; 3, always absent

152 d1: 0, always two-rooted; 1, usually two-rooted; 2, always one-
rooted

153 p2 = 0, always present; 1, usually present; 2, always absent

154 p2: paralophid = 0, isolated, spur-like; 1, curved, without constriction

155 p2: paraconid = 0, developed; 1, reduced

156 p2: posterior valley = 0, lingually open; 1, usually closed; 2,
always closed

157 Lower molars: lingual cingulum = 0, always present; 1, usually present; 2, usually absent; 3, always absent

158 Lower molars: lingual cingulum = 0, reduced; 1, continuous

159 Lower molars: labial cingulum = 0, always present; 1, usually present; 2, usually absent; 3, always absent

160 Lower molars: labial cingulum = 0, continuous; 1, reduced

161 Lower molars: hypolophid = 0, transverse; 1, oblique; 2, almost sagittal

162 m2-3: lingual groove of the entoconid = 0, absent; 1, present

163 D1 = 0, present; 1, absent

164 D12 = 0, present; 1, absent

165 D2: mesostyle = 0, present; 1, absent

166 D3-4: mesostyle = 0, absent; 1, present

167 D2: lingual wall = 0, absent; 1, present

168 D2: secondary folds = 0, absent; 1, present

169 D2: mesoloph = 0, absent; 1, present

170 d1 = 0, present; 1, absent

171 d2 = 0, present; 1, absent

172 Lower milk teeth: constriction of the metaconid = 0, present; 1, absent

173 Lower milk teeth: constriction of the entoconid = 0, absent; 1, present

174 Lower milk teeth: protoconid fold = 0, present; 1, absent

175 d1 (in juveniles) = 0, present; 1, absent

176 d2-3: vertical external roughnesses = 0, absent; 1, present

177 d2-3: ectolophid fold = 0, present; 1, absent

178 d2: anterior groove on the ectolophid = 0, absent; 1, present

179 d2: paralophid = 0, simple; 1, double

180 d2: posterior valley = 0, always open; 1, usually open; 2, usually closed; 3, always closed

181 d3: paralophid = 0, double; 1, simple

182 d3: lingual groove on the entoconid = 0, always absent; 1, usually absent; 2, always present

183 Atlas: outline of the rachidian canal = 0, bulb; 1, mushroom

184 Atlas: alar notch = 0, absent; 1, present

185 Atlas: foramen vertebrale lateralis = 0, absent; 1, present

186 Atlas: condyle-facets = 0, comma-like; 1, kidney-like

187 Atlas: axis-facets = 0, straight; 1, sigmoid; 2, transversally con-
cave (NA)

188 Atlas: foramen transversarium = 0, present; 1, absent

189 Atlas: foramen transversarium = beside the axis-facet; 1, hidden by the axis-facet

190 Scapula = 0, elongated (1.5 < H/APD ≤ 2); 1, very elongated (H/APD > 2); 2, spatula-shaped (H/APD ≤ 1.5)

191 Scapula: glenoid fossa = 0, oval; 1, medial border straight

192 Humerus: greater trochiter = 0, high; 1, low

193 Humerus: fossa olecrani = 0, high; 1, low

194 Humerus: distal articulation = 0, egg cup (shallow median con-
striction); 1, diabolo (deep median constriction)

195 Humerus: scar on the trochlea = 0, absent; 1, present

196 Humerus: distal gutter on the epicondyle = 0, absent; 1, present

197 Radius: anterior border of the proximal articulation = 0, straight; 1, M-shaped

198 Radius: medial border of the diaphysis = 0, straight; 1, concave

199 Radius: proximal ulna-facets = 0, always separated; 1, usually separated; 2, usually fused; 3, always fused

200 Radius: insertion of the m. biceps brachii = 0, shallow; 1, deep

201 Radius/ulna = 0, independent; 1, in contact or fused

202 Radius: gutter for the m. extensor carpi = 0, deep and wide; 1, weak

203 Radius/ulna: second distal articulation = 0, absent; 1, present

204 Radius: posterior expansion of the scaphoid-facet = 0, low; 1, high

205 Ulna: angle between diaphysis and olecranon = 0, open; 1, closed

206 Ulna: anterior tubercle on the distal end = 0, absent; 1, present

207 Scaphoid: postero-proximal semilunate-facet = 0, present; 1, absent or contact

208 Scaphoid: trapezium-facet = 0, large; 1, small

209 Scaphoid: magnum-facet in lateral view = 0, concave; 1, straight

210 Scaphoid: comparison between anterior and posterior heights = 0, equal; 1, H ant < H post

211 Semilunate: ulna-facet = 0, absent; 1, present

212 Semilunate: distal border of anterior side = 0, acute; 1, rounded

213 Semilunate: anterior side = 0, keeled; 1, smooth

214 Pyramidal: distal facet for semilunate = 0, symmetric; 1, asym-
metric; 2, L-shaped

215 Pyramidal: distal side = 0, triangular; 1, elliptic

216 Trapezoid: proximal border in anterior view = 0, symmetric; 1, asymmetric

217 Magnum: proximal border of the anterior side = 0, nearly straight; 1, concave

218 Magnum: indentation on the medial side = 0, absent; 1, present

219 Magnum: indentation on the medial side = 0, always shallow; 1, usually shallow; 2, always deep

220 Magnum: posterior tuberosity = 0, short; 1, long

221 Magnum: posterior tuberosity = 0, curved; 1, straight

222 Unciform: pyramidal-facet and McV-facet = 0, always separate; 1, usually separate; 2, always in contact

223 Unciform: posterior expansion of the pyramidal-facet = 0, always absent; 1, usually absent; 2, usually present; 3, always present

224 McII: magnum-facet = 0, curved; 1, straight

225 McII: anterior McIII-facet = 0, present; 1, sometimes absent

226 McII: posterior McIII-facet = 0, always absent; 1, usually absent; 2, always present

227 McII: anterior and posterior McIII-facets = 0, separated; 1, fused

228 McII: trapezium-facet = 0, always present; 1, usually present; 2, always absent

229 McIII: magnum-facet in anterior view = 0, visible; 1, invisible

230 McIV: proximal facet, outline = 0, trapezoid; 1, pentagonal; 2, triangular

231 McV: 0, functional; 1, vestigial
**232** Metacarpals: insertion of the m. extensor carpalis = 0, flat; 1, salient

**233** Coxal: acetabulum = 0, oval or circular; 1, subtriangular

**234** Femur: trochanter major = 0, high; 1, low

**235** Femur: head = 0, hemispheric; 1, medially stiff

**236** Femur: surface of epiphysis of the head = 0, flat; 1, crescent-shaped

**237** Femur: fovea capitis = 0, present; 1, absent

**238** Femur: fovea capitis = 0, high and narrow; 1, low and wide

**239** Femur: third trochanter = 0, developed; 1, very developed

**240** Femur: relations between the medial lip of the trochlea and the diaphysis = 0, broken angle; 1, ramp

**241** Femur: proximal border of the patellar trochlea = 0, curved; 1, straight

**242** Tibia: anterodistal groove = 0, present; 1, absent

**243** Tibia: mediodistal gutter (tendon m. tibialis posterior) = 0, always present; 1, usually present; 2, always absent

**244** Tibia: mediodistal gutter = 0, shallow; 1, deep

**245** Tibia-fibula = 0, independent; 1, in contact or fused

**246** Tibia: posterior apophysis = 0, high; 1, low

**247** Tibia: posterior apophysis = 0, acute; 1, rounded

**248** Fibula: proximal articulation = 0, low; 1, high

**249** Fibula: distal end = 0, slender; 1, robust

**250** Fibula: latero-distal gutter (tendon peronaeus muscles) = 0, shallow; 1, deep

**251** Fibula: position of the latero-distal gutter = 0, posterior; 1, median

**252** Astragalus: (transverse diameter/height) ratio = 0, TD/H < 1; 1, 1 <TD/H < 1.2; 2, 1.2≥TD/H

**253** Astragalus: (anteroposterior diameter/height) ratio = 0, APD/H < 0.65; 1, APD/H ≥ 0.65

**254** Astragalus: orientation of the fibula-facet = 0, subvertical; 1, oblique

**255** Astragalus: fibula-facet = 0, flat; 1, concave

**256** Astragalus: collum tali = 0, high; 1, low

**257** Astragalus: posterior stop on the cuboid-facet = 0, present; 1, absent

**258** Astragalus: caudal border of the trochlea, in proximal view = 0, sinuous; 1, nearly straight

**259** Astragalus: orientation of trochlea/distal articulation = 0, very oblique; 1, same axis

**260** Astragalus: expansion of the calcaneus-facet 1 = 0, always present; 1, usually present

**261** Astragalus: expansion of the calcaneus-facet 1 = 0, always wide and low; 1, usually wide and low; 2, always high and narrow

**262** Astragalus: calcaneus-facet 1 = 0, very concave; 1, nearly flat

**263** Astragalus: calcaneus-facets 2 and 3 = 0, always independent; 1, usually independent; 2, usually fused; 3, always fused

**264** Calcaneus: fibula-facet = 0, always absent; 1, usually absent; 2, usually present; 3, always present

**265** Calcaneus: tibia-facet = 0, always absent; 1, usually absent; 2, always present

**266** Calcaneus: tuber calcanei = 0, massive; 1, slender

**267** Calcaneus: insertion of the m. fibularis longus = 0, salient; 1, invisible

**268** Navicular: cross-section = 0, lozenge; 1, rectangle

**269** Cuboid: proximal side = 0, oval; 1, triangular

**270** Ectocuneiform: posterolateral process = 0, weak; 1, developed

**271** MtiIII: proximal border of the anterior side = 0, straight; 1, concave; 2, sigmoid

**272** MtiIII: posterior MtiII-facet = 0, present; 1, absent

**273** MtiIII: MtiIV-facets = 0, distinct; 1, sometimes joined

**274** MtiIII: distal widening of the diaphysis (in adults) = 0, absent; 1, present

**275** MtiIII: cuboid-facet = 0, absent; 1, present

**276** MtiIII: cuboid-facet = 0, small; 1, large

**277** MtiIV: posteroproximal tuberosity = 0, isolated; 1, pad-shaped and continuous

**278** Phalanx I for MtiIII: symmetric insertions = 0, lateral; 1, nearly anterior

**279** Limbs = 0, slender; 1, robust (brachypod)

**280** Metapodials: intermediate relief = 0, high and acute; 1, low and smooth

**281** Central metapodials: posterodistal tubercle on the diaphysis = 0, absent; 1, present

**282** Lateral metapodials: insertion of the m. interossei = 0, long; 1, short (does not reach distal half of the shaft)

**283** C = 0, reduced; 1, developed; 2, strong

**284** c = 0, reduced; 1, developed; 2, strong

**285** Preorbital fossa = 0, absent or reduced; 1, present

**286** Mandible: space between condylar and coronoid processes = 0, short (V-shaped); 1, wide (U-shaped)

**287** Mandible: condylar process = 0, high; 1, low

**288** m3 talonid = 0, equal or smaller than trigonid; 1, longer than trigonid

**289** M3 paracone fold = 0, absent; 1, weak; 2, strong

**290** Diastema between upper incisors and canine = 0, present; 1, absent

**291** Upper postcanine diastema = 0, long, similar to length of upper premolars; 1, short

**292** Orbit, vertical position on skull = 0, approximately at dorsoventral midline; 1, low, due to large size of frontal sinuses; 2, high

**293** I3, size to I2 = 0, similar; 1, much larger; 2, distinctly smaller

**294** I3, size to i2 = 0, similar or smaller; 1, much larger

**295** P3, size and morphology = 0, similar in length with p4 and molariform, with talonid well developed; 1, distinctly shorter than p4 and molariform; 2, distinctly shorter than p4 and premolariform, with talonid reduced or absent

**296** Upper molars, parastyle = 0, large; 1, reduced

**297** M3, metastyle direction = 0, posterolingually; 1, posterolabially

**298** P4 third posterior loph = 0, absent; 1, present
<table><caption>APPENDIX 3. — Body masses were estimated using regression equations for perissodactyls and for ungulates of Legendre (1989) or/and regression equation for Rhinocerotidae Owen, 1845 and for all ungulates of Fortelius & Kappelman (1993).</caption><thead><tr><th>Taxon</th><th>Specimen</th><th>a</th><th>x (mm²)</th><th>b</th><th>Log (Y)</th><th>Y (tons)</th><th>means</th><th>x measurements (mm)</th></tr></thead><tbody><tr><td colspan="9"><strong>Regression equation of perissodactyls of Legendre (1989)</strong></td></tr><tr><td rowspan="2">Zaisanamynodon borisovi Belyaeva, 1971</td><td>ZSN-KKS-28-IPB</td><td>1.559</td><td>2080.5</td><td>1.425</td><td>6.600</td><td>4.0</td><td>4.1</td><td>surface left m1 (57 x 36.5)</td></tr><tr><td></td><td>1.559</td><td>2156</td><td>1.425</td><td>6.624</td><td>4.2</td><td>-</td><td>surface right m1 (56 x 38.5)</td></tr><tr><td colspan="9"><strong>Regression equation of all ungulates of Legendre (1989)</strong></td></tr><tr><td rowspan="2">Zaisanamynodon borisovi</td><td>ZSN-KKS-28-IPB</td><td>1.515</td><td>2080.5</td><td>1.568</td><td>6.594</td><td>3.9</td><td>4.1</td><td>surface left m1 (57 x 36.5)</td></tr><tr><td></td><td>1.515</td><td>2156</td><td>1.568</td><td>6.624</td><td>4.2</td><td>-</td><td>surface right m1 (56 x 38.5)</td></tr><tr><td colspan="9"><strong>Regression equations of Rhinocerotidae Gray, 1821 of Fortelius & Kappelman (1993)</strong></td></tr><tr><td rowspan="7">Zaisanamynodon borisovi</td><td>ZSN-KKS-28-IPB</td><td>3.78</td><td>81</td><td>-3.33</td><td>3.884</td><td>7.7</td><td>5.7</td><td>length left M2</td></tr><tr><td></td><td>3.78</td><td>81</td><td>-3.33</td><td>3.884</td><td>7.7</td><td>-</td><td>length right M2</td></tr><tr><td></td><td>3.5</td><td>82.5</td><td>-2.98</td><td>3.728</td><td>5.3</td><td>-</td><td>length right M3</td></tr><tr><td></td><td>2.41</td><td>284</td><td>-2.6</td><td>3.312</td><td>2.1</td><td>-</td><td>TRLU (upper tooth row length)</td></tr><tr><td rowspan="7">Metamynodon planifrons</td><td>UNISTRA.2015.0.1106</td><td>3.78</td><td>50.5</td><td>-3.33</td><td>3.108</td><td>1.3</td><td>1.3</td><td>length left M2</td></tr><tr><td></td><td>3.78</td><td>50</td><td>-3.33</td><td>3.092</td><td>1.2</td><td>-</td><td>length right M2</td></tr><tr><td></td><td>3.5</td><td>60</td><td>-2.98</td><td>3.244</td><td>1.8</td><td>-</td><td>length left M3</td></tr><tr><td></td><td>3.5</td><td>60.5</td><td>-2.98</td><td>3.256</td><td>1.8</td><td>-</td><td>length right M3</td></tr><tr><td></td><td>3.02</td><td>542</td><td>-5.21</td><td>3.047</td><td>1.1</td><td>-</td><td>CBL (basicondylar length)</td></tr><tr><td></td><td>2.68</td><td>315</td><td>-3.6</td><td>3.095</td><td>1.2</td><td>-</td><td>WZYG (zygomatic width)</td></tr><tr><td></td><td>1.6</td><td>170730</td><td>-5.3</td><td>3.072</td><td>1.2</td><td>-</td><td>CBL x WZYG</td></tr><tr><td rowspan="7">VPM-9157, Holotype measurements from Scott & Osborn (1887)</td><td></td><td>3.5</td><td>60</td><td>-2.98</td><td>3.244</td><td>1.8</td><td>1.5</td><td>TRLU (upper tooth row length)</td></tr><tr><td></td><td>3.02</td><td>550</td><td>-5.21</td><td>3.066</td><td>1.2</td><td>-</td><td>length of M3</td></tr><tr><td></td><td>2.68</td><td>365</td><td>-3.6</td><td>3.267</td><td>1.8</td><td>-</td><td>CBL (basicondylar length)</td></tr><tr><td></td><td>1.6</td><td>200750</td><td>-5.3</td><td>3.184</td><td>1.5</td><td>-</td><td>CBL x WZYG</td></tr><tr><td></td><td>2.41</td><td>225</td><td>-2.6</td><td>3.069</td><td>1.2</td><td>-</td><td>TRLU (upper tooth row length)</td></tr><tr><td colspan="9"><strong>Regression equations of all ungulates of Fortelius & Kappelman (1993)</strong></td></tr><tr><td rowspan="7">Zaisanamynodon borisovi</td><td>ZSN-KKS-28-IPB</td><td>2.89</td><td>81</td><td>1.26</td><td>6.776</td><td>6.0</td><td>4.5</td><td>length left M2</td></tr><tr><td></td><td>2.89</td><td>81</td><td>1.26</td><td>6.776</td><td>6.0</td><td>-</td><td>length right M2</td></tr><tr><td></td><td>2.66</td><td>82.5</td><td>1.49</td><td>6.588</td><td>3.9</td><td>-</td><td>length right M3</td></tr><tr><td></td><td>2.99</td><td>284</td><td>-0.96</td><td>6.375</td><td>2.4</td><td>-</td><td>TRLU (upper tooth row length)</td></tr><tr><td rowspan="7">Metamynodon planifrons</td><td>UNISTRA.2015.0.1106</td><td>2.89</td><td>50.5</td><td>1.26</td><td>6.183</td><td>1.5</td><td>1.2</td><td>length left M2</td></tr><tr><td></td><td>2.89</td><td>50</td><td>1.26</td><td>6.170</td><td>1.5</td><td>-</td><td>length right M2</td></tr><tr><td></td><td>2.66</td><td>60</td><td>1.49</td><td>6.220</td><td>1.7</td><td>-</td><td>length left M3</td></tr><tr><td></td><td>2.66</td><td>60.5</td><td>1.49</td><td>6.229</td><td>1.7</td><td>-</td><td>length right M3</td></tr><tr><td></td><td>3.10</td><td>542</td><td>-2.69</td><td>5.785</td><td>0.6</td><td>-</td><td>CBL (basicondylar length)</td></tr><tr><td></td><td>3.03</td><td>315</td><td>-1.52</td><td>6.050</td><td>1.1</td><td>-</td><td>WZYG (zygomatic width)</td></tr><tr><td></td><td>1.57</td><td>170730</td><td>-2.26</td><td>5.955</td><td>0.9</td><td>-</td><td>CBL x WZYG</td></tr><tr><td rowspan="7">VPM-9157, Holotype measurements from Scott & Osborn (1887)</td><td></td><td>2.66</td><td>60</td><td>1.49</td><td>6.220</td><td>1.7</td><td>1.3</td><td>length of M3</td></tr><tr><td></td><td>3.10</td><td>550</td><td>-2.69</td><td>5.805</td><td>0.6</td><td>-</td><td>CBL (basicondylar length)</td></tr><tr><td></td><td>3.03</td><td>365</td><td>-1.52</td><td>6.244</td><td>1.8</td><td>-</td><td>WZYG (zygomatic width)</td></tr><tr><td></td><td>1.57</td><td>200750</td><td>-2.26</td><td>6.065</td><td>1.2</td><td>-</td><td>CBL x WZYG</td></tr><tr><td></td><td>2.99</td><td>225</td><td>-0.96</td><td>6.073</td><td>1.2</td><td>-</td><td>TRLU (upper tooth row length)</td></tr></tbody></table>
<table><caption>APPENDIX 4. — The list of transformations. **Simple arrow** (-->) indicates an ambiguous change; **double arrow** (==>) indicates a synapomorphy/autapomorphy (green coloured cells). Data were obtained with the “describe trees” command of PAUP*. See Appendix 5 for corresponding of nodes with the parsimonious tree. Abbreviation: CI, consistency index.</caption><thead><tr><th>Branch</th><th>Character</th><th>Steps</th><th>CI</th><th>Change</th><th>Branch</th><th>Character</th><th>Steps</th><th>CI</th><th>Change</th></tr></thead><tbody><tr><td rowspan="25">Node 36 --> Tapirus<br>terrestris (Linnaeus,<br>1758)</td><td>3</td><td>1</td><td>0.200</td><td>0 ===> 1</td><td rowspan="25">Node 37 --> Node 39</td><td>278</td><td>1</td><td>1.000</td><td>0 --> 1</td></tr><tr><td>6</td><td>1</td><td>0.500</td><td>0 ===> 1</td><td>280</td><td>1</td><td>1.000</td><td>0 ===> 1</td></tr><tr><td>10</td><td>1</td><td>0.167</td><td>1 --> 0</td><td>284</td><td>1</td><td>0.286</td><td>1 --> 0</td></tr><tr><td>11</td><td>1</td><td>0.250</td><td>1 ===> 0</td><td>286</td><td>1</td><td>0.200</td><td>0 --> 1</td></tr><tr><td>16</td><td>1</td><td>0.333</td><td>1 --> 0</td><td>47</td><td>1</td><td>0.667</td><td>0 ===> 1</td></tr><tr><td>20</td><td>1</td><td>0.286</td><td>1 ===> 0</td><td>60</td><td>1</td><td>0.286</td><td>1 --> 2</td></tr><tr><td>22</td><td>1</td><td>1.000</td><td>0 --> 1</td><td>72</td><td>1</td><td>0.500</td><td>0 --> 1</td></tr><tr><td>26</td><td>1</td><td>0.333</td><td>0 ===> 1</td><td>95</td><td>1</td><td>0.250</td><td>0 --> 1</td></tr><tr><td>34</td><td>1</td><td>0.167</td><td>0 ===> 1</td><td>99</td><td>1</td><td>0.143</td><td>1 --> 0</td></tr><tr><td>38</td><td>1</td><td>0.500</td><td>1 ===> 0</td><td>102</td><td>1</td><td>0.333</td><td>0 --> 1</td></tr><tr><td>40</td><td>1</td><td>1.000</td><td>0 ===> 1</td><td>108</td><td>1</td><td>0.250</td><td>1 --> 0</td></tr><tr><td>53</td><td>1</td><td>0.143</td><td>1 --> 0</td><td>109</td><td>1</td><td>0.200</td><td>1 --> 0</td></tr><tr><td>55</td><td>1</td><td>0.250</td><td>0 ===> 1</td><td>110</td><td>1</td><td>0.214</td><td>1 ===> 2</td></tr><tr><td>56</td><td>1</td><td>0.167</td><td>1 ===> 0</td><td>118</td><td>1</td><td>0.143</td><td>0 ===> 1</td></tr><tr><td>97</td><td>1</td><td>0.500</td><td>0 ===> 1</td><td>119</td><td>1</td><td>0.333</td><td>0 ===> 1</td></tr><tr><td>99</td><td>1</td><td>0.143</td><td>1 --> 0</td><td>144</td><td>1</td><td>0.333</td><td>1 --> 0</td></tr><tr><td>102</td><td>1</td><td>0.333</td><td>0 --> 2</td><td>147</td><td>2</td><td>0.429</td><td>2 --> 0</td></tr><tr><td>108</td><td>1</td><td>0.250</td><td>1 --> 0</td><td>283</td><td>1</td><td>0.400</td><td>0 --> 1</td></tr><tr><td>109</td><td>1</td><td>0.200</td><td>1 --> 0</td><td>287</td><td>1</td><td>0.333</td><td>0 ===> 1</td></tr><tr><td>110</td><td>1</td><td>0.214</td><td>1 --> 0</td><td>289</td><td>1</td><td>0.167</td><td>2 ===> 1</td></tr><tr><td>142</td><td>1</td><td>0.333</td><td>0 ===> 1</td><td>37</td><td>1</td><td>0.143</td><td>0 --> 1</td></tr><tr><td>144</td><td>1</td><td>0.333</td><td>1 --> 0</td><td>55</td><td>1</td><td>0.250</td><td>0 ===> 1</td></tr><tr><td>147</td><td>2</td><td>0.429</td><td>2 --> 0</td><td>92</td><td>1</td><td>1.000</td><td>0 --> 1</td></tr><tr><td>150</td><td>1</td><td>0.250</td><td>0 ===> 1</td><td>114</td><td>1</td><td>0.158</td><td>2 --> 3</td></tr><tr><td>151</td><td>3</td><td>0.300</td><td>0 ===> 3</td><td>121</td><td>1</td><td>0.167</td><td>0 ===> 1</td></tr><tr><td>157</td><td>2</td><td>0.250</td><td>2 ===> 0</td><td>146</td><td>1</td><td>0.333</td><td>1 --> 0</td></tr><tr><td>160</td><td>1</td><td>0.250</td><td>0 --> 1</td><td>148</td><td>1</td><td>0.500</td><td>0 ===> 1</td></tr><tr><td>179</td><td>1</td><td>0.500</td><td>1 --> 0</td><td>151</td><td>3</td><td>0.300</td><td>0 ===> 3</td></tr><tr><td>181</td><td>1</td><td>0.500</td><td>0 --> 1</td><td>152</td><td>2</td><td>0.333</td><td>2 --> 0</td></tr><tr><td>184</td><td>1</td><td>0.500</td><td>1 --> 0</td><td>158</td><td>1</td><td>0.500</td><td>0 --> 1</td></tr><tr><td>185</td><td>1</td><td>0.500</td><td>0 --> 1</td><td>179</td><td>1</td><td>0.500</td><td>1 --> 0</td></tr><tr><td>187</td><td>1</td><td>1.000</td><td>0 ===> 1</td><td>198</td><td>1</td><td>0.500</td><td>0 --> 1</td></tr><tr><td>209</td><td>1</td><td>0.500</td><td>0 ===> 1</td><td>201</td><td>1</td><td>0.333</td><td>0 ===> 1</td></tr><tr><td>213</td><td>1</td><td>0.333</td><td>1 --> 0</td><td>207</td><td>1</td><td>0.333</td><td>0 ===> 1</td></tr><tr><td>238</td><td>1</td><td>0.333</td><td>1 --> 0</td><td>221</td><td>1</td><td>1.000</td><td>0 --> 1</td></tr><tr><td>244</td><td>1</td><td>0.500</td><td>0 --> 1</td><td>228</td><td>2</td><td>0.500</td><td>0 ===> 2</td></tr><tr><td>254</td><td>1</td><td>0.200</td><td>0 ===> 1</td><td>241</td><td>1</td><td>0.333</td><td>0 --> 1</td></tr><tr><td>263</td><td>1</td><td>0.300</td><td>1 --> 0</td><td>253</td><td>1</td><td>0.500</td><td>0 --> 1</td></tr><tr><td>292</td><td>1</td><td>0.333</td><td>0 ===> 1</td><td>259</td><td>1</td><td>1.000</td><td>0 --> 1</td></tr><tr><td>293</td><td>1</td><td>0.400</td><td>0 ===> 1</td><td>263</td><td>2</td><td>0.300</td><td>1 --> 3</td></tr><tr><td>294</td><td>1</td><td>0.250</td><td>0 --> 1</td><td>24</td><td>1</td><td>0.333</td><td>0 --> 1</td></tr><tr><td>296</td><td>1</td><td>0.500</td><td>0 ===> 1</td><td>60</td><td>1</td><td>0.286</td><td>2 --> 1</td></tr><tr><td rowspan="25">Node 36 --> Node<br>37</td><td>42</td><td>1</td><td>0.400</td><td>0 --> 1</td><td rowspan="25">Node 40 --> Node 43</td><td>63</td><td>1</td><td>0.400</td><td>0 ===> 1</td></tr><tr><td>54</td><td>1</td><td>0.333</td><td>0 ===> 1</td><td>89</td><td>2</td><td>0.250</td><td>0 ===> 2</td></tr><tr><td>70</td><td>1</td><td>0.500</td><td>0 --> 1</td><td>97</td><td>1</td><td>0.500</td><td>0 ===> 1</td></tr><tr><td>86</td><td>1</td><td>0.333</td><td>0 ===> 1</td><td>103</td><td>1</td><td>0.200</td><td>1 --> 0</td></tr><tr><td>114</td><td>2</td><td>0.158</td><td>0 ===> 2</td><td>180</td><td>3</td><td>1.000</td><td>0 --> 3</td></tr><tr><td>120</td><td>1</td><td>0.125</td><td>0 ===> 1</td><td>183</td><td>1</td><td>0.500</td><td>0 --> 1</td></tr><tr><td>138</td><td>1</td><td>0.250</td><td>0 --> 1</td><td>185</td><td>1</td><td>0.500</td><td>0 --> 1</td></tr><tr><td>146</td><td>1</td><td>0.333</td><td>0 --> 1</td><td>190</td><td>1</td><td>1.000</td><td>1 --> 2</td></tr><tr><td>152</td><td>2</td><td>0.333</td><td>0 --> 2</td><td>191</td><td>1</td><td>0.500</td><td>0 --> 1</td></tr><tr><td>161</td><td>1</td><td>0.400</td><td>0 ===> 1</td><td>212</td><td>1</td><td>0.250</td><td>1 ===> 0</td></tr><tr><td>173</td><td>1</td><td>1.000</td><td>0 --> 1</td><td>247</td><td>1</td><td>1.000</td><td>0 ===> 1</td></tr><tr><td>175</td><td>1</td><td>1.000</td><td>0 --> 1</td><td>252</td><td>2</td><td>0.500</td><td>0 ===> 2</td></tr><tr><td>177</td><td>1</td><td>1.000</td><td>0 --> 1</td><td>276</td><td>1</td><td>1.000</td><td>0 --> 1</td></tr><tr><td>186</td><td>1</td><td>1.000</td><td>0 --> 1</td><td>285</td><td>1</td><td>1.000</td><td>0 ===> 1</td></tr><tr><td>190</td><td>1</td><td>1.000</td><td>0 --> 1</td><td>297</td><td>1</td><td>1.000</td><td>0 --> 1</td></tr><tr><td>192</td><td>1</td><td>0.500</td><td>0 --> 1</td><td>7</td><td>1</td><td>0.250</td><td>0 --> 1</td></tr><tr><td>197</td><td>1</td><td>1.000</td><td>0 --> 1</td><td>16</td><td>1</td><td>0.333</td><td>1 --> 0</td></tr><tr><td>208</td><td>1</td><td>0.500</td><td>0 --> 1</td><td>63</td><td>1</td><td>0.400</td><td>1 ===> 2</td></tr><tr><td>226</td><td>2</td><td>0.500</td><td>0 --> 2</td><td>67</td><td>1</td><td>1.000</td><td>0 --> 1</td></tr><tr><td>229</td><td>1</td><td>0.500</td><td>0 --> 1</td><td>88</td><td>1</td><td>0.500</td><td>0 --> 1</td></tr><tr><td>231</td><td>1</td><td>0.500</td><td>0 ===> 1</td><td>91</td><td>1</td><td>0.400</td><td>0 ===> 1</td></tr><tr><td>258</td><td>1</td><td>0.500</td><td>0 --> 1</td><td>94</td><td>1</td><td>0.429</td><td>2 ===> 0</td></tr><tr><td>261</td><td>2</td><td>0.333</td><td>0 --> 2</td><td>102</td><td>1</td><td>0.333</td><td>1 ===> 0</td></tr><tr><td>264</td><td>3</td><td>1.000</td><td>0 ===> 3</td><td>110</td><td>1</td><td>0.214</td><td>2 ===> 1</td></tr><tr><td>265</td><td>2</td><td>0.667</td><td>0 --> 2</td><td>114</td><td>2</td><td>0.158</td><td>3 ===> 1</td></tr><tr><td></td><td></td><td></td><td></td><td></td><td></td><td>118</td><td>1</td><td>0.143</td><td>1 ===> 0</td></tr></tbody></table>
<table><caption>APPENDIX 4. — Continuation.</caption><thead><tr><th>Branch</th><th>Character</th><th>Steps</th><th>CI</th><th>Change</th><th>Branch</th><th>Character</th><th>Steps</th><th>CI</th><th>Change</th></tr></thead><tbody><tr><td></td><td>142</td><td>1</td><td>0.333</td><td>0 --&gt; 1</td><td></td><td>65</td><td>1</td><td>0.143</td><td>0 --&gt; 1</td></tr><tr><td></td><td>143</td><td>1</td><td>0.500</td><td>1 --&gt; 0</td><td></td><td>288</td><td>1</td><td>0.333</td><td>0 --&gt; 1</td></tr><tr><td></td><td>157</td><td>2</td><td>0.250</td><td>2 --&gt; 0</td><td>Node 62 --&gt; Node 61</td><td>10</td><td>1</td><td>0.167</td><td>0 --&gt; 1</td></tr><tr><td></td><td>188</td><td>1</td><td>0.333</td><td>0 --&gt; 1</td><td></td><td>38</td><td>1</td><td>0.500</td><td>1 --&gt; 0</td></tr><tr><td></td><td>199</td><td>3</td><td>0.333</td><td>0 --&gt; 3</td><td></td><td>53</td><td>1</td><td>0.143</td><td>1 --&gt; 0</td></tr><tr><td></td><td>200</td><td>1</td><td>1.000</td><td>0 --&gt; 1</td><td></td><td>54</td><td>1</td><td>0.333</td><td>1 --&gt; 2</td></tr><tr><td></td><td>220</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td><td></td><td>56</td><td>1</td><td>0.167</td><td>1 --&gt; 0</td></tr><tr><td></td><td>231</td><td>1</td><td>0.500</td><td>1 --&gt; 0</td><td></td><td>60</td><td>1</td><td>0.286</td><td>1 --&gt; 0</td></tr><tr><td></td><td>249</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td><td></td><td>149</td><td>1</td><td>0.333</td><td>0 --&gt; 1</td></tr><tr><td></td><td>256</td><td>1</td><td>0.250</td><td>0 --&gt; 1</td><td></td><td>159</td><td>3</td><td>0.167</td><td>0 --&gt; 3</td></tr><tr><td></td><td>270</td><td>1</td><td>1.000</td><td>0 --&gt; 1</td><td></td><td>289</td><td>1</td><td>0.167</td><td>2 --&gt; 1</td></tr><tr><td></td><td>284</td><td>2</td><td>0.286</td><td>0 --&gt; 2</td><td>Node 61 --&gt;</td><td>102</td><td>1</td><td>0.333</td><td>0 --&gt; 2</td></tr><tr><td>Node 44 --&gt; Node 45</td><td>2</td><td>1</td><td>0.250</td><td>0 --&gt; 1</td><td>Metamynodon</td><td>111</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td></tr><tr><td>(Amynodontidae)</td><td>8</td><td>1</td><td>0.333</td><td>0 --&gt; 1</td><td>planifrons Scott & Osborn, 1887</td><td>112</td><td>1</td><td>0.333</td><td>0 --&gt; 1</td></tr><tr><td>Scott & Osborn, 1883)</td><td>10</td><td>1</td><td>0.167</td><td>1 --&gt; 0</td><td></td><td>120</td><td>1</td><td>0.125</td><td>0 --&gt; 1</td></tr><tr><td></td><td>65</td><td>1</td><td>0.143</td><td>0 --&gt; 1</td><td>Node 61 --&gt; UNIS-TRA.2015.0.1106</td><td>13</td><td>1</td><td>1.000</td><td>0 --&gt; 1</td></tr><tr><td></td><td>83</td><td>2</td><td>0.200</td><td>0 --&gt; 2</td><td></td><td>45</td><td>1</td><td>0.250</td><td>0 --&gt; 1</td></tr><tr><td></td><td>86</td><td>1</td><td>0.333</td><td>1 --&gt; 0</td><td></td><td>99</td><td>1</td><td>0.143</td><td>0 --&gt; 1</td></tr><tr><td></td><td>91</td><td>1</td><td>0.400</td><td>1 --&gt; 2</td><td></td><td>103</td><td>1</td><td>0.200</td><td>2 --&gt; 1</td></tr><tr><td></td><td>109</td><td>3</td><td>0.200</td><td>1 --&gt; 2</td><td></td><td>114</td><td>2</td><td>0.158</td><td>1 --&gt; 3</td></tr><tr><td></td><td>283</td><td>1</td><td>0.400</td><td>1 --&gt; 2</td><td></td><td>117</td><td>1</td><td>1.000</td><td>0 --&gt; 1</td></tr><tr><td></td><td>296</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td><td></td><td>121</td><td>1</td><td>0.167</td><td>1 --&gt; 0</td></tr><tr><td>Node 45 --&gt; Node 46</td><td>7</td><td>1</td><td>0.250</td><td>1 --&gt; 0</td><td></td><td>292</td><td>1</td><td>0.333</td><td>2 --&gt; 0</td></tr><tr><td></td><td>11</td><td>1</td><td>0.250</td><td>1 --&gt; 0</td><td>Node 60 --&gt; Node 59</td><td>37</td><td>1</td><td>0.143</td><td>1 --&gt; 0</td></tr><tr><td></td><td>19</td><td>1</td><td>0.250</td><td>1 --&gt; 2</td><td></td><td>61</td><td>1</td><td>0.333</td><td>0 --&gt; 1</td></tr><tr><td></td><td>23</td><td>1</td><td>0.250</td><td>0 --&gt; 1</td><td></td><td>105</td><td>1</td><td>0.188</td><td>0 --&gt; 1</td></tr><tr><td></td><td>34</td><td>1</td><td>0.167</td><td>0 --&gt; 1</td><td></td><td>212</td><td>1</td><td>0.250</td><td>0 --&gt; 1</td></tr><tr><td></td><td>36</td><td>1</td><td>0.286</td><td>1 --&gt; 0</td><td></td><td>256</td><td>1</td><td>0.250</td><td>1 --&gt; 0</td></tr><tr><td>Node 46 --&gt; Node 47</td><td>12</td><td>1</td><td>0.200</td><td>0 --&gt; 1</td><td></td><td>274</td><td>1</td><td>0.333</td><td>0 --&gt; 1</td></tr><tr><td></td><td>20</td><td>1</td><td>0.286</td><td>1 --&gt; 0</td><td></td><td>290</td><td>1</td><td>0.200</td><td>1 --&gt; 0</td></tr><tr><td></td><td>26</td><td>1</td><td>0.333</td><td>0 --&gt; 1</td><td></td><td>293</td><td>1</td><td>0.400</td><td>0 --&gt; 1</td></tr><tr><td></td><td>83</td><td>1</td><td>0.200</td><td>2 --&gt; 3</td><td>Node 59 --&gt;</td><td>48</td><td>1</td><td>0.250</td><td>0 --&gt; 1</td></tr><tr><td></td><td>88</td><td>1</td><td>0.500</td><td>1 --&gt; 0</td><td>Megalamynodon</td><td>56</td><td>1</td><td>0.167</td><td>1 --&gt; 0</td></tr><tr><td></td><td>89</td><td>1</td><td>0.250</td><td>2 --&gt; 1</td><td>regalis Wood, 1945</td><td>77</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td></tr><tr><td></td><td>103</td><td>1</td><td>0.200</td><td>0 --&gt; 1</td><td></td><td>102</td><td>1</td><td>0.333</td><td>0 --&gt; 2</td></tr><tr><td></td><td>155</td><td>1</td><td>0.333</td><td>0 --&gt; 1</td><td></td><td>112</td><td>1</td><td>0.333</td><td>0 --&gt; 1</td></tr><tr><td></td><td>165</td><td>1</td><td>0.500</td><td>1 --&gt; 0</td><td></td><td>284</td><td>1</td><td>0.286</td><td>2 --&gt; 1</td></tr><tr><td></td><td>167</td><td>1</td><td>1.000</td><td>0 --&gt; 1</td><td>Node 59 --&gt;</td><td>53</td><td>1</td><td>0.143</td><td>1 --&gt; 0</td></tr><tr><td></td><td>289</td><td>1</td><td>0.167</td><td>1 --&gt; 2</td><td>Paramynodon</td><td>98</td><td>1</td><td>0.250</td><td>0 --&gt; 1</td></tr><tr><td></td><td>292</td><td>1</td><td>0.333</td><td>0 --&gt; 1</td><td>birmanicus</td><td>114</td><td>1</td><td>0.158</td><td>1 --&gt; 0</td></tr><tr><td>Node 47 --&gt; Node 58</td><td>8</td><td>1</td><td>0.333</td><td>1 --&gt; 0</td><td>(Pilgrim & Cotter, 2016)</td><td>150</td><td>1</td><td>0.250</td><td>0 --&gt; 1</td></tr><tr><td></td><td>65</td><td>1</td><td>0.143</td><td>1 --&gt; 0</td><td></td><td>159</td><td>2</td><td>0.167</td><td>0 --&gt; 2</td></tr><tr><td></td><td>110</td><td>1</td><td>0.214</td><td>1 --&gt; 0</td><td></td><td>291</td><td>1</td><td>0.250</td><td>1 --&gt; 0</td></tr><tr><td></td><td>120</td><td>1</td><td>0.125</td><td>1 --&gt; 0</td><td>Node 58 --&gt; Node 57 (Cadurcodontini Wall, 1982)</td><td>34</td><td>1</td><td>0.167</td><td>1 --&gt; 0</td></tr><tr><td></td><td>140</td><td>1</td><td>0.400</td><td>1 --&gt; 0</td><td></td><td>42</td><td>1</td><td>0.400</td><td>1 --&gt; 2</td></tr><tr><td></td><td>153</td><td>2</td><td>0.667</td><td>0 --&gt; 2</td><td></td><td>66</td><td>1</td><td>1.000</td><td>0 --&gt; 1</td></tr><tr><td></td><td>290</td><td>1</td><td>0.200</td><td>0 --&gt; 1</td><td></td><td>83</td><td>3</td><td>0.200</td><td>3 --&gt; 0</td></tr><tr><td></td><td>292</td><td>1</td><td>0.333</td><td>1 --&gt; 2</td><td></td><td>118</td><td>1</td><td>0.143</td><td>0 --&gt; 1</td></tr><tr><td></td><td>295</td><td>2</td><td>0.286</td><td>0 --&gt; 2</td><td></td><td>193</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td></tr><tr><td>Node 58 --&gt; Node 60</td><td>11</td><td>1</td><td>0.250</td><td>0 --&gt; 1</td><td></td><td>198</td><td>1</td><td>0.500</td><td>1 --&gt; 0</td></tr><tr><td>(Metamynodontini)</td><td>42</td><td>1</td><td>0.400</td><td>1 --&gt; 0</td><td></td><td>202</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td></tr><tr><td>Scott & Osborn, 1887)</td><td>103</td><td>1</td><td>0.200</td><td>1 --&gt; 2</td><td></td><td>245</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td></tr><tr><td></td><td>158</td><td>1</td><td>0.500</td><td>1 --&gt; 0</td><td></td><td>287</td><td>1</td><td>0.333</td><td>1 --&gt; 0</td></tr><tr><td></td><td>194</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td><td></td><td>288</td><td>1</td><td>0.333</td><td>0 --&gt; 1</td></tr><tr><td></td><td>195</td><td>1</td><td>1.000</td><td>0 --&gt; 1</td><td>Node 57 --&gt; Node 54</td><td>10</td><td>1</td><td>0.167</td><td>0 --&gt; 1</td></tr><tr><td></td><td>275</td><td>1</td><td>0.333</td><td>0 --&gt; 1</td><td></td><td>12</td><td>1</td><td>0.200</td><td>1 --&gt; 0</td></tr><tr><td></td><td>291</td><td>1</td><td>0.250</td><td>0 --&gt; 1</td><td></td><td>19</td><td>1</td><td>0.250</td><td>2 --&gt; 1</td></tr><tr><td>Node 60 --&gt; Node 62</td><td>12</td><td>1</td><td>0.200</td><td>1 --&gt; 0</td><td></td><td>23</td><td>1</td><td>0.250</td><td>1 --&gt; 0</td></tr><tr><td></td><td>18</td><td>2</td><td>0.500</td><td>0 --&gt; 2</td><td></td><td>77</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td></tr><tr><td></td><td>39</td><td>1</td><td>1.000</td><td>0 --&gt; 1</td><td></td><td>124</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td></tr><tr><td></td><td>211</td><td>1</td><td>0.333</td><td>0 --&gt; 1</td><td></td><td>127</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td></tr><tr><td></td><td>254</td><td>1</td><td>0.200</td><td>0 --&gt; 1</td><td></td><td>192</td><td>1</td><td>0.500</td><td>1 --&gt; 0</td></tr><tr><td></td><td>255</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td><td></td><td>238</td><td>1</td><td>0.333</td><td>1 --&gt; 0</td></tr><tr><td></td><td>279</td><td>1</td><td>1.000</td><td>0 --&gt; 1</td><td></td><td>246</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td></tr><tr><td>Node 62 --&gt;</td><td>11</td><td>1</td><td>0.250</td><td>1 --&gt; 2</td><td></td><td>255</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td></tr><tr><td>Sellamynodon</td><td>15</td><td>2</td><td>0.500</td><td>0 --&gt; 2</td><td></td><td>292</td><td>1</td><td>0.333</td><td>2 --&gt; 1</td></tr><tr><td>zimborensis</td><td>20</td><td>1</td><td>0.286</td><td>0 --&gt; 1</td><td></td><td>294</td><td>1</td><td>0.250</td><td>0 --&gt; 1</td></tr><tr><td>(Codrea & Suraru, 1989)</td><td>49</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td><td>Node 54 --&gt; Node 50</td><td>11</td><td>1</td><td>0.250</td><td>0 --&gt; 1</td></tr><tr><td></td><td>57</td><td>1</td><td>1.000</td><td>0 --&gt; 1</td><td></td><td>19</td><td>1</td><td>0.250</td><td>1 --&gt; 0</td></tr><tr><td></td><td>60</td><td>1</td><td>0.286</td><td>1 --&gt; 2</td><td></td><td>21</td><td>1</td><td>1.000</td><td>0 --&gt; 1</td></tr></tbody></table>
APPENDIX 4. — Continuation.

<table><thead><tr><th>Branch</th><th>Character</th><th>Steps</th><th>CI</th><th>Change</th><th>Branch</th><th>Character</th><th>Steps</th><th>CI</th><th>Change</th></tr></thead><tbody><tr><td></td><td>34</td><td>1</td><td>0.167</td><td>0 --> 1</td><td></td><td>78</td><td>1</td><td>0.333</td><td>0 --> 1</td></tr><tr><td></td><td>61</td><td>1</td><td>0.333</td><td>0 --> 1</td><td></td><td>81</td><td>1</td><td>0.250</td><td>0 --> 1</td></tr><tr><td></td><td>71</td><td>1</td><td>1.000</td><td>0 --> 1</td><td></td><td>89</td><td>1</td><td>0.250</td><td>1 --> 2</td></tr><tr><td></td><td>76</td><td>1</td><td>1.000</td><td>0 --> 1</td><td></td><td>114</td><td>2</td><td>0.158</td><td>1 --> 3</td></tr><tr><td></td><td>110</td><td>1</td><td>0.214</td><td>0 --> 1</td><td></td><td>149</td><td>1</td><td>0.333</td><td>0 --> 1</td></tr><tr><td></td><td>118</td><td>1</td><td>0.143</td><td>1 --> 0</td><td></td><td>161</td><td>1</td><td>0.400</td><td>1 --> 2</td></tr><tr><td></td><td>126</td><td>2</td><td>1.000</td><td>0 --> 2</td><td></td><td>287</td><td>1</td><td>0.333</td><td>0 --> 1</td></tr><tr><td></td><td>274</td><td>1</td><td>0.333</td><td>0 --> 1</td><td>Node 52 --> Cadu-<br/>rcotherium cayluxi</td><td>103</td><td>1</td><td>0.200</td><td>0 --> 1</td></tr><tr><td></td><td>291</td><td>1</td><td>0.250</td><td>0 --> 1</td><td>Gervais, 1873</td><td>127</td><td>1</td><td>0.500</td><td>1 --> 0</td></tr><tr><td></td><td>293</td><td>1</td><td>0.400</td><td>0 --> 2</td><td>Node 52 --> Cadu-<br/>rcotherium minum<br/>Filhol, 1880</td><td>288</td><td>1</td><td>0.333</td><td>1 --> 0</td></tr><tr><td>Node 50 --> Node 49</td><td>3</td><td>1</td><td>0.200</td><td>1 --> 0</td><td>Node 57 --> Node 56</td><td>83</td><td>3</td><td>0.200</td><td>0 --> 3</td></tr><tr><td></td><td>53</td><td>1</td><td>0.143</td><td>1 --> 0</td><td></td><td>2</td><td>1</td><td>0.250</td><td>1 --> 0</td></tr><tr><td></td><td>59</td><td>1</td><td>0.500</td><td>0 --> 1</td><td></td><td>25</td><td>2</td><td>0.667</td><td>0 --> 2</td></tr><tr><td></td><td>78</td><td>1</td><td>0.333</td><td>0 --> 1</td><td></td><td>36</td><td>1</td><td>0.286</td><td>0 --> 1</td></tr><tr><td></td><td>161</td><td>1</td><td>0.400</td><td>1 --> 2</td><td></td><td>37</td><td>1</td><td>0.143</td><td>1 --> 0</td></tr><tr><td>Node 49 --> Node 48</td><td>68</td><td>1</td><td>0.500</td><td>0 --> 1</td><td></td><td>56</td><td>1</td><td>0.167</td><td>1 --> 0</td></tr><tr><td></td><td>73</td><td>1</td><td>0.500</td><td>0 --> 1</td><td></td><td>99</td><td>1</td><td>0.143</td><td>0 --> 1</td></tr><tr><td></td><td>74</td><td>1</td><td>0.250</td><td>0 --> 1</td><td></td><td>109</td><td>2</td><td>0.200</td><td>3 --> 1</td></tr><tr><td></td><td>81</td><td>1</td><td>0.250</td><td>0 --> 1</td><td></td><td>114</td><td>1</td><td>0.158</td><td>1 --> 2</td></tr><tr><td></td><td>89</td><td>1</td><td>0.250</td><td>1 --> 2</td><td></td><td>120</td><td>1</td><td>0.125</td><td>0 --> 1</td></tr><tr><td></td><td>90</td><td>3</td><td>1.000</td><td>0 --> 3</td><td></td><td>254</td><td>1</td><td>0.200</td><td>0 --> 1</td></tr><tr><td></td><td>102</td><td>1</td><td>0.333</td><td>0 --> 3</td><td></td><td>256</td><td>1</td><td>0.250</td><td>1 --> 0</td></tr><tr><td></td><td>104</td><td>1</td><td>0.250</td><td>0 --> 1</td><td></td><td>286</td><td>1</td><td>0.200</td><td>1 --> 0</td></tr><tr><td></td><td>107</td><td>3</td><td>0.750</td><td>0 --> 3</td><td></td><td>293</td><td>1</td><td>0.400</td><td>0 --> 1</td></tr><tr><td></td><td>111</td><td>1</td><td>0.500</td><td>0 --> 1</td><td></td><td>298</td><td>1</td><td>1.000</td><td>0 --> 1</td></tr><tr><td></td><td>114</td><td>1</td><td>0.158</td><td>1 --> 2</td><td>Node 56 --> Node 55</td><td>53</td><td>1</td><td>0.143</td><td>1 --> 2</td></tr><tr><td>Node 48 --> Cadu-<br/>rcodon kazakade-<br/>mius Biryukov, 1961</td><td>286</td><td>1</td><td>0.200</td><td>1 --> 0</td><td></td><td>91</td><td>1</td><td>0.400</td><td>2 --> 1</td></tr><tr><td>Node 49 --> Cadurco-<br/>don maomingensis</td><td>65</td><td>1</td><td>0.143</td><td>0 --> 1</td><td></td><td>98</td><td>1</td><td>0.250</td><td>0 --> 1</td></tr><tr><td>Averianov, Danilov,<br/>Jin & Wang, 2016</td><td>121</td><td>1</td><td>0.167</td><td>1 --> 0</td><td></td><td>114</td><td>1</td><td>0.158</td><td>2 --> 3</td></tr><tr><td>Node 50 --> Cadu-<br/>rcodon bahoensis<br/>(Xu, 1965)</td><td>53</td><td>1</td><td>0.143</td><td>1 --> 2</td><td></td><td>153</td><td>1</td><td>0.667</td><td>2 --> 1</td></tr><tr><td>Node 54 --> Node 53</td><td>8</td><td>1</td><td>0.333</td><td>0 --> 1</td><td>Node 55 --><br/>ZSN-KKS-28-IPB</td><td>289</td><td>1</td><td>0.167</td><td>2 --> 1</td></tr><tr><td></td><td>24</td><td>1</td><td>0.333</td><td>1 --> 0</td><td></td><td>295</td><td>1</td><td>0.286</td><td>2 --> 1</td></tr><tr><td></td><td>60</td><td>1</td><td>0.286</td><td>1 --> 0</td><td></td><td>103</td><td>1</td><td>0.200</td><td>1 --> 2</td></tr><tr><td></td><td>95</td><td>1</td><td>0.250</td><td>1 --> 0</td><td></td><td>104</td><td>1</td><td>0.250</td><td>0 --> 1</td></tr><tr><td></td><td>102</td><td>1</td><td>0.333</td><td>0 --> 2</td><td></td><td>105</td><td>3</td><td>0.188</td><td>0 --> 3</td></tr><tr><td></td><td>103</td><td>1</td><td>0.200</td><td>1 --> 0</td><td></td><td>108</td><td>1</td><td>0.250</td><td>0 --> 1</td></tr><tr><td></td><td>105</td><td>3</td><td>0.188</td><td>0 --> 3</td><td></td><td>137</td><td>1</td><td>1.000</td><td>0 --> 1</td></tr><tr><td></td><td>159</td><td>3</td><td>0.167</td><td>0 --> 3</td><td>Node 56 --> Zaisana-<br/>mynodon protheroi<br/>Lucas, 2006</td><td>148</td><td>1</td><td>0.500</td><td>1 --> 0</td></tr><tr><td></td><td>271</td><td>1</td><td>0.333</td><td>2 --> 1</td><td>Node 47 --><br/>Sharamynodon<br/>mongoliensis<br/>(Osborn, 1936)</td><td>53</td><td>1</td><td>0.143</td><td>1 --> 2</td></tr><tr><td>Node 53 --> Node 51</td><td>37</td><td>1</td><td>0.143</td><td>1 --> 0</td><td></td><td>55</td><td>1</td><td>0.250</td><td>1 --> 0</td></tr><tr><td></td><td>44</td><td>1</td><td>0.333</td><td>0 --> 1</td><td></td><td>70</td><td>1</td><td>0.500</td><td>1 --> 0</td></tr><tr><td></td><td>54</td><td>1</td><td>0.333</td><td>1 --> 0</td><td></td><td>98</td><td>1</td><td>0.250</td><td>0 --> 1</td></tr><tr><td></td><td>94</td><td>1</td><td>0.429</td><td>0 --> 2</td><td></td><td>114</td><td>1</td><td>0.158</td><td>1 --> 0</td></tr><tr><td></td><td>140</td><td>1</td><td>0.400</td><td>0 --> 1</td><td></td><td>141</td><td>1</td><td>0.250</td><td>0 --> 1</td></tr><tr><td></td><td>289</td><td>1</td><td>0.167</td><td>2 --> 1</td><td></td><td>209</td><td>1</td><td>0.500</td><td>0 --> 1</td></tr><tr><td></td><td>290</td><td>1</td><td>0.200</td><td>1 --> 0</td><td></td><td>271</td><td>2</td><td>0.333</td><td>2 --> 0</td></tr><tr><td></td><td>295</td><td>2</td><td>0.286</td><td>2 --> 0</td><td></td><td>283</td><td>1</td><td>0.400</td><td>2 --> 1</td></tr><tr><td>Node 51 --><br/>Amynodontopsis<br/>bodei Stock, 1933</td><td>36</td><td>1</td><td>0.286</td><td>0 --> 1</td><td>Node 46 --><br/>Amynodon advenus<br/>(Marsh, 1875)</td><td>2</td><td>1</td><td>0.250</td><td>1 --> 0</td></tr><tr><td></td><td>45</td><td>1</td><td>0.250</td><td>0 --> 1</td><td></td><td>37</td><td>1</td><td>0.143</td><td>1 --> 0</td></tr><tr><td></td><td>109</td><td>3</td><td>0.200</td><td>3 --> 0</td><td></td><td>48</td><td>1</td><td>0.250</td><td>0 --> 1</td></tr><tr><td>Node 51 --><br/>Amynodontopsis jiyu-<br/>anensis Wang X.-Y.,<br/>Wang Y.-Q., Zhang</td><td>3</td><td>1</td><td>0.200</td><td>1 --> 0</td><td></td><td>53</td><td>1</td><td>0.143</td><td>1 --> 0</td></tr><tr><td>R., Zhang Z.-H., Liu &<br/>Ren, 2020</td><td>26</td><td>1</td><td>0.333</td><td>1 --> 0</td><td></td><td>60</td><td>1</td><td>0.286</td><td>1 --> 0</td></tr><tr><td>Node 53 --> Node 52</td><td>48</td><td>1</td><td>0.250</td><td>0 --> 1</td><td></td><td>99</td><td>1</td><td>0.143</td><td>0 --> 1</td></tr><tr><td></td><td>110</td><td>2</td><td>0.214</td><td>0 --> 2</td><td></td><td>105</td><td>1</td><td>0.188</td><td>0 --> 1</td></tr><tr><td></td><td>120</td><td>1</td><td>0.125</td><td>0 --> 1</td><td></td><td>150</td><td>1</td><td>0.250</td><td>0 --> 1</td></tr><tr><td></td><td>122</td><td>1</td><td>0.500</td><td>0 --> 1</td><td></td><td>156</td><td>2</td><td>1.000</td><td>0 --> 2</td></tr><tr><td></td><td>7</td><td>1</td><td>0.250</td><td>0 --> 1</td><td>Node 45 --><br/>Rostriamynodon<br/>grangeri Wall &<br/>Manning, 1986</td><td>56</td><td>1</td><td>0.167</td><td>1 --> 0</td></tr><tr><td></td><td>10</td><td>1</td><td>0.167</td><td>1 --> 0</td><td></td><td>110</td><td>1</td><td>0.214</td><td>1 --> 0</td></tr><tr><td></td><td>19</td><td>1</td><td>0.250</td><td>1 --> 2</td><td></td><td>120</td><td>1</td><td>0.125</td><td>1 --> 0</td></tr><tr><td></td><td>20</td><td>1</td><td>0.286</td><td>0 --> 1</td><td></td><td>140</td><td>1</td><td>0.400</td><td>1 --> 2</td></tr><tr><td></td><td>25</td><td>1</td><td>0.667</td><td>0 --> 1</td><td></td><td>293</td><td>1</td><td>0.400</td><td>0 --> 2</td></tr><tr><td></td><td>65</td><td>1</td><td>0.143</td><td>0 --> 1</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td></td><td>68</td><td>1</td><td>0.500</td><td>0 --> 1</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td></td><td>74</td><td>1</td><td>0.250</td><td>0 --> 1</td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>
<table><caption>APPENDIX 4. — Continuation.</caption><thead><tr><th>Branch</th><th>Character</th><th>Steps</th><th>CI</th><th>Change</th><th>Branch</th><th>Character</th><th>Steps</th><th>CI</th><th>Change</th></tr></thead><tbody><tr><td>Node 44 --&gt;</td><td>24</td><td>1</td><td>0.333</td><td>1 --&gt; 0</td><td></td><td>105</td><td>3</td><td>0.188</td><td>0 ==&gt; 3</td></tr><tr><td>"Pappaceras"</td><td>45</td><td>1</td><td>0.250</td><td>0 ==&gt; 1</td><td></td><td>112</td><td>2</td><td>0.333</td><td>0 ==&gt; 2</td></tr><tr><td>meiomenus Wang</td><td>114</td><td>1</td><td>0.158</td><td>1 ==&gt; 0</td><td></td><td>178</td><td>1</td><td>1.000</td><td>0 ==&gt; 1</td></tr><tr><td>H.-B., Bai, Meng &amp; Wang Y.-Q., 2016</td><td>119</td><td>1</td><td>0.333</td><td>1 ==&gt; 0</td><td></td><td>181</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td></tr><tr><td>Node 43 --&gt; Node 42 (Paraceratheriidae Osborn, 1923)</td><td>3</td><td>1</td><td>0.200</td><td>0 --&gt; 1</td><td></td><td>182</td><td>2</td><td>1.000</td><td>0 ==&gt; 2</td></tr><tr><td></td><td>15</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td><td></td><td>275</td><td>1</td><td>0.333</td><td>0 ==&gt; 1</td></tr><tr><td></td><td>19</td><td>1</td><td>0.250</td><td>1 --&gt; 0</td><td></td><td>283</td><td>1</td><td>0.400</td><td>1 --&gt; 0</td></tr><tr><td></td><td>35</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td><td></td><td>286</td><td>1</td><td>0.200</td><td>1 --&gt; 0</td></tr><tr><td></td><td>37</td><td>1</td><td>0.143</td><td>1 --&gt; 0</td><td></td><td>290</td><td>1</td><td>0.200</td><td>0 ==&gt; 1</td></tr><tr><td></td><td>44</td><td>1</td><td>0.333</td><td>0 --&gt; 1</td><td></td><td>7</td><td>1</td><td>0.250</td><td>0 --&gt; 1</td></tr><tr><td></td><td>53</td><td>1</td><td>0.143</td><td>1 ==&gt; 2</td><td>Node 39 --&gt; Node 38 (Eggysodontidae Breuning, 1923)</td><td>11</td><td>1</td><td>0.250</td><td>1 --&gt; 0</td></tr><tr><td></td><td>73</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td><td></td><td>53</td><td>1</td><td>0.143</td><td>1 --&gt; 0</td></tr><tr><td></td><td>74</td><td>1</td><td>0.250</td><td>0 --&gt; 1</td><td></td><td>94</td><td>1</td><td>0.429</td><td>2 ==&gt; 1</td></tr><tr><td></td><td>75</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td><td></td><td>103</td><td>1</td><td>0.200</td><td>1 ==&gt; 2</td></tr><tr><td></td><td>99</td><td>1</td><td>0.143</td><td>0 --&gt; 1</td><td></td><td>133</td><td>1</td><td>0.333</td><td>0 ==&gt; 1</td></tr><tr><td></td><td>133</td><td>1</td><td>0.333</td><td>0 ==&gt; 1</td><td></td><td>157</td><td>2</td><td>0.250</td><td>2 --&gt; 0</td></tr><tr><td></td><td>141</td><td>1</td><td>0.250</td><td>0 --&gt; 1</td><td></td><td>160</td><td>1</td><td>0.250</td><td>0 --&gt; 1</td></tr><tr><td></td><td>168</td><td>1</td><td>1.000</td><td>0 --&gt; 1</td><td></td><td>202</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td></tr><tr><td></td><td>169</td><td>1</td><td>1.000</td><td>0 --&gt; 1</td><td></td><td>217</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td></tr><tr><td></td><td>187</td><td>1</td><td>1.000</td><td>0 ==&gt; 2</td><td></td><td>249</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td></tr><tr><td></td><td>229</td><td>1</td><td>0.500</td><td>1 --&gt; 0</td><td></td><td>263</td><td>1</td><td>0.300</td><td>1 --&gt; 0</td></tr><tr><td></td><td>234</td><td>1</td><td>1.000</td><td>0 --&gt; 1</td><td></td><td>268</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td></tr><tr><td></td><td>241</td><td>1</td><td>0.333</td><td>1 --&gt; 0</td><td></td><td>271</td><td>1</td><td>0.333</td><td>2 --&gt; 1</td></tr><tr><td></td><td>246</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td><td></td><td>283</td><td>1</td><td>0.400</td><td>1 --&gt; 2</td></tr><tr><td></td><td>263</td><td>3</td><td>0.300</td><td>3 --&gt; 0</td><td></td><td>284</td><td>2</td><td>0.286</td><td>0 ==&gt; 2</td></tr><tr><td></td><td>274</td><td>1</td><td>0.333</td><td>0 --&gt; 1</td><td></td><td>291</td><td>1</td><td>0.250</td><td>0 --&gt; 1</td></tr><tr><td></td><td>294</td><td>1</td><td>0.250</td><td>0 --&gt; 1</td><td>Node 38 --&gt; Allacerops turgaica (Borissiak, 1915)</td><td>63</td><td>1</td><td>0.400</td><td>0 ==&gt; 1</td></tr><tr><td>Node 42 --&gt; Node 41</td><td>54</td><td>1</td><td>0.333</td><td>1 --&gt; 2</td><td></td><td>89</td><td>1</td><td>0.250</td><td>0 ==&gt; 1</td></tr><tr><td></td><td>65</td><td>1</td><td>0.143</td><td>0 --&gt; 1</td><td></td><td>105</td><td>3</td><td>0.188</td><td>0 ==&gt; 3</td></tr><tr><td></td><td>78</td><td>1</td><td>0.333</td><td>0 ==&gt; 1</td><td></td><td>140</td><td>1</td><td>0.400</td><td>1 ==&gt; 2</td></tr><tr><td></td><td>81</td><td>1</td><td>0.250</td><td>0 ==&gt; 1</td><td></td><td>141</td><td>1</td><td>0.250</td><td>0 ==&gt; 1</td></tr><tr><td></td><td>82</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td><td></td><td>155</td><td>1</td><td>0.333</td><td>0 ==&gt; 1</td></tr><tr><td></td><td>138</td><td>1</td><td>0.250</td><td>1 --&gt; 0</td><td>Node 38 --&gt; Eggysodon osborni (Schlosser, 1902)</td><td>95</td><td>1</td><td>0.250</td><td>1 --&gt; 0</td></tr><tr><td></td><td>159</td><td>1</td><td>0.167</td><td>0 --&gt; 1</td><td></td><td>114</td><td>2</td><td>0.158</td><td>2 ==&gt; 0</td></tr><tr><td>Node 41 --&gt;</td><td>11</td><td>1</td><td>0.250</td><td>1 ==&gt; 0</td><td></td><td>138</td><td>1</td><td>0.250</td><td>1 --&gt; 0</td></tr><tr><td>Paraceratherium bugtiense Forster</td><td>47</td><td>1</td><td>0.667</td><td>1 ==&gt; 2</td><td></td><td>154</td><td>1</td><td>0.333</td><td>1 ==&gt; 0</td></tr><tr><td>Cooper, 1911</td><td>48</td><td>1</td><td>0.250</td><td>0 ==&gt; 1</td><td></td><td>211</td><td>1</td><td>0.333</td><td>0 ==&gt; 1</td></tr><tr><td></td><td>91</td><td>2</td><td>0.400</td><td>0 ==&gt; 2</td><td></td><td>212</td><td>1</td><td>0.250</td><td>1 ==&gt; 0</td></tr><tr><td></td><td>94</td><td>1</td><td>0.429</td><td>2 ==&gt; 1</td><td></td><td>224</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td></tr><tr><td></td><td>103</td><td>1</td><td>0.200</td><td>0 --&gt; 1</td><td></td><td>256</td><td>1</td><td>0.250</td><td>0 ==&gt; 1</td></tr><tr><td></td><td>110</td><td>1</td><td>0.214</td><td>2 ==&gt; 3</td><td></td><td>272</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td></tr><tr><td></td><td>124</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td><td>Node 37 --&gt; Teletaceras radin-skyi Hanson, 1989</td><td>1</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td></tr><tr><td></td><td>128</td><td>2</td><td>1.000</td><td>0 ==&gt; 2</td><td></td><td>36</td><td>1</td><td>0.286</td><td>1 ==&gt; 0</td></tr><tr><td></td><td>155</td><td>1</td><td>0.333</td><td>0 ==&gt; 1</td><td></td><td>46</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td></tr><tr><td></td><td>292</td><td>1</td><td>0.333</td><td>0 ==&gt; 1</td><td></td><td>65</td><td>1</td><td>0.143</td><td>0 ==&gt; 1</td></tr><tr><td></td><td>36</td><td>1</td><td>0.286</td><td>1 ==&gt; 0</td><td></td><td>79</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td></tr><tr><td>Node 41 --&gt;</td><td>89</td><td>1</td><td>0.250</td><td>2 --&gt; 1</td><td></td><td>83</td><td>3</td><td>0.200</td><td>0 ==&gt; 3</td></tr><tr><td>Paraceratherium transouralicum (Pavlow, 1922)</td><td>110</td><td>2</td><td>0.214</td><td>2 ==&gt; 0</td><td></td><td>94</td><td>1</td><td>0.429</td><td>2 ==&gt; 3</td></tr><tr><td></td><td>118</td><td>1</td><td>0.143</td><td>1 ==&gt; 0</td><td></td><td>104</td><td>1</td><td>0.250</td><td>0 ==&gt; 1</td></tr><tr><td></td><td>121</td><td>1</td><td>0.167</td><td>1 ==&gt; 0</td><td></td><td>109</td><td>2</td><td>0.200</td><td>1 ==&gt; 3</td></tr><tr><td></td><td>217</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td><td></td><td>111</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td></tr><tr><td></td><td>83</td><td>2</td><td>0.200</td><td>0 ==&gt; 2</td><td></td><td>147</td><td>1</td><td>0.429</td><td>2 ==&gt; 3</td></tr><tr><td>Node 42 --&gt;</td><td>120</td><td>1</td><td>0.125</td><td>1 ==&gt; 0</td><td></td><td>154</td><td>1</td><td>0.333</td><td>1 ==&gt; 0</td></tr><tr><td>Urtinotherium intermedium (Chiu, 1962)</td><td>151</td><td>3</td><td>0.300</td><td>3 ==&gt; 0</td><td></td><td>159</td><td>3</td><td>0.167</td><td>0 ==&gt; 3</td></tr><tr><td></td><td>161</td><td>1</td><td>0.400</td><td>1 ==&gt; 0</td><td></td><td>294</td><td>1</td><td>0.250</td><td>0 --&gt; 1</td></tr><tr><td></td><td>252</td><td>1</td><td>0.500</td><td>2 --&gt; 1</td><td>Node 36 --&gt; Node 35</td><td>18</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td></tr><tr><td></td><td>254</td><td>1</td><td>0.200</td><td>0 ==&gt; 1</td><td></td><td>19</td><td>1</td><td>0.250</td><td>1 ==&gt; 0</td></tr><tr><td></td><td>261</td><td>2</td><td>0.333</td><td>2 --&gt; 0</td><td></td><td>20</td><td>1</td><td>0.286</td><td>1 --&gt; 2</td></tr><tr><td></td><td>289</td><td>1</td><td>0.167</td><td>1 ==&gt; 2</td><td></td><td>63</td><td>1</td><td>0.400</td><td>0 ==&gt; 1</td></tr><tr><td></td><td>295</td><td>2</td><td>0.286</td><td>0 ==&gt; 2</td><td></td><td>143</td><td>1</td><td>0.500</td><td>1 ==&gt; 0</td></tr><tr><td></td><td>12</td><td>1</td><td>0.200</td><td>0 ==&gt; 1</td><td></td><td>165</td><td>1</td><td>0.500</td><td>1 ==&gt; 0</td></tr><tr><td>Node 40 --&gt;</td><td>19</td><td>1</td><td>0.250</td><td>1 ==&gt; 2</td><td></td><td>188</td><td>1</td><td>0.333</td><td>0 --&gt; 1</td></tr><tr><td>Hyracodon nebraskensis (Leidy, 1850)</td><td>34</td><td>1</td><td>0.167</td><td>0 ==&gt; 1</td><td></td><td>199</td><td>1</td><td>0.333</td><td>0 --&gt; 1</td></tr><tr><td></td><td>36</td><td>1</td><td>0.286</td><td>1 ==&gt; 2</td><td></td><td>218</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td></tr><tr><td></td><td>42</td><td>1</td><td>0.400</td><td>1 --&gt; 0</td><td></td><td>227</td><td>1</td><td>1.000</td><td>0 --&gt; 1</td></tr><tr><td></td><td>45</td><td>1</td><td>0.250</td><td>0 ==&gt; 1</td><td></td><td>242</td><td>1</td><td>1.000</td><td>1 ==&gt; 0</td></tr><tr><td></td><td>46</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td><td></td><td>250</td><td>1</td><td>1.000</td><td>1 ==&gt; 0</td></tr><tr><td></td><td>54</td><td>1</td><td>0.333</td><td>1 ==&gt; 0</td><td>Node 35 --&gt; Node 34 (Rhinocerotidae Gray, 1821)</td><td>10</td><td>1</td><td>0.167</td><td>1 --&gt; 0</td></tr><tr><td></td><td>59</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td><td></td><td>23</td><td>1</td><td>0.250</td><td>0 --&gt; 1</td></tr><tr><td></td><td></td><td></td><td></td><td></td><td></td><td>44</td><td>1</td><td>0.333</td><td>0 ==&gt; 1</td></tr></tbody></table>
<table><caption>APPENDIX 4. — Continuation.</caption><thead><tr><th>Branch</th><th>Character</th><th>Steps</th><th>CI</th><th>Change</th><th>Branch</th><th>Character</th><th>Steps</th><th>CI</th><th>Change</th></tr></thead><tbody><tr><td></td><td>53</td><td>1</td><td>0.143</td><td>1 --&gt; 2</td><td></td><td>61</td><td>1</td><td>0.333</td><td>0 ==&gt; 1</td></tr><tr><td></td><td>79</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td><td></td><td>63</td><td>1</td><td>0.400</td><td>1 ==&gt; 0</td></tr><tr><td></td><td>81</td><td>1</td><td>0.250</td><td>0 ==&gt; 1</td><td></td><td>94</td><td>1</td><td>0.429</td><td>2 ==&gt; 1</td></tr><tr><td></td><td>82</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td><td></td><td>102</td><td>1</td><td>0.333</td><td>2 ==&gt; 3</td></tr><tr><td></td><td>102</td><td>1</td><td>0.333</td><td>0 --&gt; 2</td><td></td><td>105</td><td>1</td><td>0.188</td><td>1 ==&gt; 2</td></tr><tr><td></td><td>118</td><td>1</td><td>0.143</td><td>0 --&gt; 1</td><td></td><td>108</td><td>1</td><td>0.250</td><td>1 ==&gt; 0</td></tr><tr><td></td><td>154</td><td>1</td><td>0.333</td><td>1 ==&gt; 0</td><td></td><td>112</td><td>1</td><td>0.333</td><td>1 ==&gt; 2</td></tr><tr><td></td><td>159</td><td>2</td><td>0.167</td><td>0 --&gt; 2</td><td></td><td>118</td><td>1</td><td>0.143</td><td>1 --&gt; 0</td></tr><tr><td></td><td>191</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td><td></td><td>147</td><td>1</td><td>0.429</td><td>2 ==&gt; 1</td></tr><tr><td></td><td>212</td><td>1</td><td>0.250</td><td>1 ==&gt; 0</td><td></td><td>157</td><td>1</td><td>0.250</td><td>1 ==&gt; 0</td></tr><tr><td></td><td>213</td><td>1</td><td>0.333</td><td>1 --&gt; 0</td><td></td><td>159</td><td>2</td><td>0.167</td><td>2 --&gt; 0</td></tr><tr><td></td><td>220</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td><td></td><td>194</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td></tr><tr><td></td><td>223</td><td>1</td><td>1.000</td><td>0 ==&gt; 1</td><td></td><td>199</td><td>2</td><td>0.333</td><td>1 ==&gt; 3</td></tr><tr><td></td><td>230</td><td>1</td><td>1.000</td><td>0 --&gt; 1</td><td></td><td>218</td><td>1</td><td>0.500</td><td>1 ==&gt; 0</td></tr><tr><td></td><td>252</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td><td></td><td>230</td><td>1</td><td>1.000</td><td>1 ==&gt; 2</td></tr><tr><td></td><td>253</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td><td></td><td>238</td><td>1</td><td>0.333</td><td>1 --&gt; 0</td></tr><tr><td></td><td>271</td><td>2</td><td>0.333</td><td>2 ==&gt; 0</td><td></td><td>261</td><td>1</td><td>0.333</td><td>1 ==&gt; 2</td></tr><tr><td></td><td>290</td><td>1</td><td>0.200</td><td>0 --&gt; 1</td><td></td><td>265</td><td>1</td><td>0.667</td><td>0 ==&gt; 1</td></tr><tr><td rowspan="18">Node 34 --&gt; Trigonias osborni Lucas, 1900</td><td>1</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td><td rowspan="18">Node 33 --&gt; Aceratherium incisivum (Cuvier, 1824)</td><td>17</td><td>1</td><td>1.000</td><td>0 ==&gt; 1</td></tr><tr><td>6</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td><td>19</td><td>1</td><td>0.250</td><td>0 ==&gt; 1</td></tr><tr><td>47</td><td>1</td><td>0.667</td><td>0 ==&gt; 1</td><td>23</td><td>1</td><td>0.250</td><td>1 --&gt; 0</td></tr><tr><td>49</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td><td>29</td><td>1</td><td>1.000</td><td>0 ==&gt; 1</td></tr><tr><td>55</td><td>1</td><td>0.250</td><td>0 ==&gt; 1</td><td>34</td><td>1</td><td>0.167</td><td>0 ==&gt; 1</td></tr><tr><td>72</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td><td>54</td><td>1</td><td>0.333</td><td>0 ==&gt; 1</td></tr><tr><td>109</td><td>1</td><td>0.200</td><td>1 --&gt; 0</td><td>86</td><td>1</td><td>0.333</td><td>0 ==&gt; 1</td></tr><tr><td>149</td><td>1</td><td>0.333</td><td>0 ==&gt; 1</td><td>95</td><td>1</td><td>0.250</td><td>0 ==&gt; 1</td></tr><tr><td>174</td><td>1</td><td>1.000</td><td>0 ==&gt; 1</td><td>99</td><td>1</td><td>0.143</td><td>1 --&gt; 0</td></tr><tr><td>183</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td><td>100</td><td>1</td><td>1.000</td><td>0 ==&gt; 1</td></tr><tr><td>188</td><td>1</td><td>0.333</td><td>1 --&gt; 0</td><td>101</td><td>2</td><td>1.000</td><td>0 ==&gt; 2</td></tr><tr><td>199</td><td>1</td><td>0.333</td><td>1 --&gt; 0</td><td>103</td><td>1</td><td>0.200</td><td>1 ==&gt; 2</td></tr><tr><td>208</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td><td>109</td><td>1</td><td>0.200</td><td>1 ==&gt; 2</td></tr><tr><td>214</td><td>1</td><td>1.000</td><td>0 ==&gt; 1</td><td>111</td><td>1</td><td>0.500</td><td>2 ==&gt; 3</td></tr><tr><td>241</td><td>1</td><td>0.333</td><td>0 ==&gt; 1</td><td>113</td><td>1</td><td>1.000</td><td>0 ==&gt; 1</td></tr><tr><td>243</td><td>1</td><td>1.000</td><td>0 ==&gt; 1</td><td>114</td><td>1</td><td>0.158</td><td>0 ==&gt; 1</td></tr><tr><td>263</td><td>1</td><td>0.300</td><td>1 --&gt; 0</td><td>115</td><td>3</td><td>1.000</td><td>0 ==&gt; 3</td></tr><tr><td>266</td><td>1</td><td>1.000</td><td>0 ==&gt; 1</td><td>122</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td></tr><tr><td>282</td><td>1</td><td>1.000</td><td>0 ==&gt; 1</td><td>125</td><td>1</td><td>1.000</td><td>0 ==&gt; 1</td></tr><tr><td rowspan="22">Node 34 --&gt; Node 33</td><td>18</td><td>1</td><td>0.500</td><td>1 --&gt; 0</td><td>129</td><td>1</td><td>1.000</td><td>0 ==&gt; 1</td></tr><tr><td>20</td><td>1</td><td>0.286</td><td>2 --&gt; 1</td><td>133</td><td>1</td><td>0.333</td><td>0 ==&gt; 1</td></tr><tr><td>36</td><td>1</td><td>0.286</td><td>1 ==&gt; 0</td><td>134</td><td>1</td><td>1.000</td><td>0 ==&gt; 1</td></tr><tr><td>42</td><td>1</td><td>0.400</td><td>0 --&gt; 1</td><td>135</td><td>2</td><td>1.000</td><td>0 ==&gt; 2</td></tr><tr><td>58</td><td>1</td><td>1.000</td><td>0 --&gt; 1</td><td>138</td><td>1</td><td>0.250</td><td>0 --&gt; 1</td></tr><tr><td>74</td><td>1</td><td>0.250</td><td>0 ==&gt; 1</td><td>140</td><td>1</td><td>0.400</td><td>1 ==&gt; 0</td></tr><tr><td>75</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td><td>142</td><td>1</td><td>0.333</td><td>0 ==&gt; 1</td></tr><tr><td>89</td><td>1</td><td>0.250</td><td>0 ==&gt; 1</td><td>146</td><td>1</td><td>0.333</td><td>0 ==&gt; 1</td></tr><tr><td>105</td><td>1</td><td>0.188</td><td>0 ==&gt; 1</td><td>150</td><td>1</td><td>0.250</td><td>0 ==&gt; 1</td></tr><tr><td>107</td><td>1</td><td>0.750</td><td>0 ==&gt; 1</td><td>151</td><td>1</td><td>0.300</td><td>0 ==&gt; 1</td></tr><tr><td>110</td><td>1</td><td>0.214</td><td>1 ==&gt; 2</td><td>152</td><td>2</td><td>0.333</td><td>0 ==&gt; 2</td></tr><tr><td>111</td><td>2</td><td>0.500</td><td>0 ==&gt; 2</td><td>160</td><td>1</td><td>0.250</td><td>0 --&gt; 1</td></tr><tr><td>112</td><td>1</td><td>0.333</td><td>0 ==&gt; 1</td><td>161</td><td>1</td><td>0.400</td><td>0 ==&gt; 1</td></tr><tr><td>119</td><td>1</td><td>0.333</td><td>0 ==&gt; 1</td><td>193</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td></tr><tr><td>120</td><td>1</td><td>0.125</td><td>0 ==&gt; 1</td><td>196</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td></tr><tr><td>144</td><td>1</td><td>0.333</td><td>1 --&gt; 0</td><td>201</td><td>1</td><td>0.333</td><td>0 ==&gt; 1</td></tr><tr><td>157</td><td>1</td><td>0.250</td><td>2 --&gt; 1</td><td>204</td><td>1</td><td>1.000</td><td>0 ==&gt; 1</td></tr><tr><td>222</td><td>2</td><td>1.000</td><td>0 --&gt; 2</td><td>205</td><td>1</td><td>1.000</td><td>0 ==&gt; 1</td></tr><tr><td>223</td><td>1</td><td>1.000</td><td>1 --&gt; 2</td><td>206</td><td>1</td><td>1.000</td><td>0 ==&gt; 1</td></tr><tr><td>228</td><td>2</td><td>0.500</td><td>0 ==&gt; 2</td><td>207</td><td>1</td><td>0.333</td><td>0 ==&gt; 1</td></tr><tr><td>258</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td><td>210</td><td>1</td><td>1.000</td><td>0 ==&gt; 1</td></tr><tr><td>261</td><td>1</td><td>0.333</td><td>0 ==&gt; 1</td><td>213</td><td>1</td><td>0.333</td><td>0 --&gt; 1</td></tr><tr><td>268</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td><td>216</td><td>1</td><td>1.000</td><td>0 ==&gt; 1</td></tr><tr><td>286</td><td>1</td><td>0.200</td><td>0 --&gt; 1</td><td>224</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td></tr><tr><td rowspan="10">Node 33 --&gt; Ronzotherium filholi (Osborn, 1900)</td><td>2</td><td>1</td><td>0.250</td><td>0 ==&gt; 1</td><td>226</td><td>2</td><td>0.500</td><td>0 ==&gt; 2</td></tr><tr><td>11</td><td>1</td><td>0.250</td><td>1 ==&gt; 0</td><td>232</td><td>1</td><td>1.000</td><td>0 ==&gt; 1</td></tr><tr><td>12</td><td>1</td><td>0.200</td><td>0 ==&gt; 1</td><td>244</td><td>1</td><td>0.500</td><td>0 --&gt; 1</td></tr><tr><td>15</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td><td>245</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td></tr><tr><td>20</td><td>1</td><td>0.286</td><td>1 ==&gt; 0</td><td>251</td><td>1</td><td>1.000</td><td>0 ==&gt; 1</td></tr><tr><td>35</td><td>1</td><td>0.500</td><td>0 ==&gt; 1</td><td>254</td><td>1</td><td>0.200</td><td>0 ==&gt; 1</td></tr><tr><td>37</td><td>1</td><td>0.143</td><td>0 ==&gt; 1</td><td>16</td><td>1</td><td>0.333</td><td>1 --&gt; 0</td></tr><tr><td>53</td><td>2</td><td>0.143</td><td>2 --&gt; 0</td><td>53</td><td>1</td><td>0.143</td><td>1 --&gt; 0</td></tr><tr><td>56</td><td>1</td><td>0.167</td><td>1 ==&gt; 0</td><td>60</td><td>1</td><td>0.286</td><td>1 ==&gt; 2</td></tr></tbody></table>
<table><caption>APPENDIX 4. — Continuation.</caption><thead><tr><th>Branch</th><th>Character</th><th>Steps</th><th>CI</th><th>Change</th></tr></thead><tbody><tr><td></td><td>83</td><td>1</td><td>0.200</td><td>0 ===> 1</td></tr><tr><td></td><td>94</td><td>1</td><td>0.429</td><td>2 ===> 0</td></tr><tr><td></td><td>98</td><td>1</td><td>0.250</td><td>0 ===> 1</td></tr><tr><td></td><td>104</td><td>1</td><td>0.250</td><td>0 ===> 1</td></tr><tr><td></td><td>109</td><td>1</td><td>0.200</td><td>1 ===> 2</td></tr><tr><td></td><td>110</td><td>1</td><td>0.214</td><td>1 --> 0</td></tr><tr><td></td><td>121</td><td>1</td><td>0.167</td><td>0 ===> 1</td></tr><tr><td></td><td>147</td><td>1</td><td>0.429</td><td>2 ===> 3</td></tr><tr><td></td><td>184</td><td>1</td><td>0.500</td><td>1 --> 0</td></tr><tr><td></td><td>196</td><td>1</td><td>0.500</td><td>0 ===> 1</td></tr><tr><td></td><td>199</td><td>2</td><td>0.333</td><td>1 ===> 3</td></tr><tr><td></td><td>201</td><td>1</td><td>0.333</td><td>0 ===> 1</td></tr><tr><td></td><td>207</td><td>1</td><td>0.333</td><td>0 ===> 1</td></tr><tr><td></td><td>211</td><td>1</td><td>0.333</td><td>0 ===> 1</td></tr><tr><td></td><td>263</td><td>2</td><td>0.300</td><td>1 ===> 3</td></tr><tr><td></td><td>272</td><td>1</td><td>0.500</td><td>0 ===> 1</td></tr><tr><td></td><td>275</td><td>1</td><td>0.333</td><td>0 ===> 1</td></tr></tbody></table>
<figure><img src="image_18.png" /><figcaption>APPENDIX 5. — Single parsimonious tree of Amynodontidae Scott & Osborn, 1883 within Rhinoceroidea Owen, 1845, with *Tapirus terrestris* (Linnaeus, 1758) and *Hyrachyus eximius* Leidy, 1871 considered as outgroups. Tree length = 805; CI = 0.3938; RI = 0.4906. Numbers inside white circles are node numbers.</figcaption></figure>
<table><caption>APPENDIX 6. — List of occurrences of Amynodontopsis Stock, 1933, *Cadurcotherium* Gervais, 1873, *Metamynodon* Scott & Osborn, 1887, *Zaisanamynodon* Belyaeva, 1971 and other genera of Amynodontidae Scott & Osborn, 1883 in Asia, Europe, and North America, range from middle Eocene to late Oligocene.</caption><thead><tr><th>Ages</th><th>Taxa</th><th>Countries</th><th>Localities</th><th>References</th></tr></thead><tbody><tr><td rowspan="10">Oligocene late</td><td rowspan="2">Cadurcotherium Gervais, 1873</td><td>Bosnia and Herzegovina</td><td>Ugljevik</td><td>Malez & Thenius (1985)</td></tr><tr><td>Pakistan</td><td>Bugti Hills</td><td>Antoine et al. (2004)</td></tr><tr><td rowspan="5">Other Cadurcotherium early-late</td><td>Kazakhstan</td><td>Akespe</td><td>Birjukov (1961); Lucas & Emry (1996)</td></tr><tr><td>France</td><td>Aubenas-les-Alpes</td><td>Ménouret et al. (2015)</td></tr><tr><td rowspan="4">Spain</td><td>Briatexte, Tarn</td><td>Roman & Joleaud (1909)</td></tr><tr><td>Le Garouillas, Tarn-et-Garonne</td><td>De Bonis (1995)</td></tr><tr><td>Rigal-Jouet, Tarn-et-Garonne</td><td>Ménouret (2018)</td></tr><tr><td>Carrascosa del Campo</td><td>Crusafont Pairó & Aguirre (1973)</td></tr><tr><td rowspan="5">Other</td><td>Kazakhstan</td><td>Kalmakpay Mountain, Zaysan Basin</td><td>Russell & Zhai (1987); Lucas & Emry (1996); Emry et al. (1998)</td></tr><tr><td rowspan="3">France</td><td>Myneske-Suyek, Dzhilanchik Basin</td><td>Birjukov (1961); Russell & Zhai (1987); Lucas & Emry (1996)</td></tr><tr><td>Barlières, Haute-Loire</td><td>Ménouret (2018)</td></tr><tr><td>Dausse, Lot-et-Garonne</td><td>Roman & Joleaud (1909); Ménouret (2018)</td></tr><tr><td rowspan="10">Metamynodon Scott & Osborn, 1887</td><td rowspan="5">Germany Switzerland United States</td><td>Etampes, Essonne</td><td>Ménouret (2018)</td></tr><tr><td>Isle-sur-Sorgue, Vaucluse</td><td>Roman & Joleaud (1909)</td></tr><tr><td>Moissac, Tarn-et-Garonne</td><td></td></tr><tr><td>Puylaurens, Tarn</td><td></td></tr><tr><td>Pech Crabit, Lot</td><td>Ménouret (2018)</td></tr><tr><td rowspan="4">China</td><td>Vendèze, Cantal</td><td>Ménouret (2018)</td></tr><tr><td>Weinheim-Alzey</td><td>Ménouret (2018)</td></tr><tr><td>Bressaucourt, Canton du Jura</td><td>Becker (2009)</td></tr><tr><td>North Dakota</td><td>Wall (1998)</td></tr><tr><td rowspan="2">Other</td><td rowspan="2">Kazakhstan Mongolia</td><td>South Dakota</td><td>Wall (1998); This study</td></tr><tr><td>Bassin Lunan and Yuezhow, Yunnan Province</td><td>Xu (1966); Russell & Zhai (1987)</td></tr><tr><td rowspan="5">Other</td><td rowspan="5">China</td><td>Suhaitu, Haosibuerdu Basin, Inner Mongolia</td><td>Russell & Zhai (1987)</td></tr><tr><td>Sunid Zuoqi, Inner Mongolia</td><td>Russell & Zhai (1987); Emry et al. (1998)</td></tr><tr><td>Kiin Kerish III, Zaysan Basin</td><td>Dashzeveg (1996)</td></tr><tr><td>Dzamyn Ude</td><td>Russell & Zhai (1987)</td></tr><tr><td>Ergilin-Dzo and Khoer-Dzan, Gua-Teg, Dornogobi Province</td><td></td></tr><tr><td rowspan="2">?late Eocene-?early Oligocene</td><td rowspan="2">Other</td><td>China</td><td>Lantian Basin, Shaanxi Province</td><td>Xu (1965); Russell & Zhai (1987)</td></tr><tr><td>Romania</td><td>Dobârca</td><td>Tissier et al. (2018)</td></tr><tr><td rowspan="10">Eocene late</td><td rowspan="2">Amynodontopsis</td><td>China</td><td>Urtyn Obo, Ulan Gochu (Inner Mongolia)</td><td>Wall (1980); Wang (1992)</td></tr><tr><td>Mexico</td><td>Bassin Tlaxiaco</td><td>Jiménez-Hidalgo et al. (2015)</td></tr><tr><td rowspan="2">Amynodontopsis?</td><td rowspan="2">Romania</td><td>Morlaca</td><td>Tissier et al. (2018)</td></tr><tr><td>South Dakota</td><td>Gillet (1960); Wall (1998)</td></tr><tr><td rowspan="2">Metamynodon</td><td rowspan="2">United States</td><td>Mississippi</td><td></td></tr><tr><td>Texas</td><td></td></tr><tr><td rowspan="2">Zaisanamynodon</td><td rowspan="2">China</td><td>Ulan Shireh Obo, Baron Sog Lamasery, Urtyn Obo (Inner Mongolia)</td><td>Lucas et al. (1996)</td></tr><tr><td>Tatsukawa Colliery, Imari City, Saga</td><td>Miyata et al. (2011)</td></tr><tr><td rowspan="10">Other</td><td rowspan="5">Japan Kazakhstan</td><td>Kiin Kerish II, Zaysan Basin</td><td>Belyaeva (1971); Russell & Zhai (1987); This study</td></tr><tr><td rowspan="5">Bulgaria China</td><td>Nikolaevo, Kameno</td><td>Nikolov & Heissig (1985)</td></tr><tr><td>Jiyuan Basin, Henan Province</td><td>Russell & Zhai (1987)</td></tr><tr><td>Wucheng Basin, Henan Province</td><td></td></tr><tr><td>Yuanqu Basin, Shanxi Province</td><td>Young (1937); Russell & Zhai (1987)</td></tr><tr><td>Lushi, Henan Province</td><td>Chow & Xu (1965)</td></tr><tr><td rowspan="5">Hungary Japan China</td><td>Mianchi, Henan Province</td><td></td></tr><tr><td>Tientong, Guangxi</td><td>Chow (1957)</td></tr><tr><td>Ula Usu, Inner Mongolia</td><td>Osborn (1936); Xu (1966)</td></tr><tr><td>Tápiószele</td><td>Kretzoi (1940)</td></tr><tr><td>Karatsu</td><td>Tomida & Yamakasi (1996)</td></tr><tr><td rowspan="3">Amynodontopsis</td><td rowspan="3">China</td><td>Maoming Basin</td><td>Averianov et al. (2016)</td></tr><tr><td>Jiyuan Basin, Henan Basin</td><td>Wang et al. (2020)</td></tr><tr><td>California</td><td>Wall (1998)</td></tr><tr><td rowspan="2">middle-late</td><td rowspan="2">Other</td><td rowspan="2">China</td><td>California</td><td></td></tr><tr><td>Montana</td><td></td></tr><tr><td rowspan="2">middle</td><td rowspan="2">Amynodontopsis</td><td>United States</td><td></td><td></td></tr><tr><td></td><td></td><td></td></tr></tbody></table>
APPENDIX 6. — Continuation.

<table><thead><tr><th>Ages</th><th>Taxa</th><th>Countries</th><th>Localities</th><th>References</th></tr></thead><tbody><tr><td></td><td></td><td></td><td>Texas</td><td></td></tr><tr><td></td><td></td><td></td><td>Utah</td><td></td></tr><tr><td></td><td></td><td></td><td>Wyoming</td><td></td></tr><tr><td></td><td>Amynodontopsis?</td><td>Hungary</td><td>Dorog</td><td>Tissier et al. (2018)</td></tr><tr><td></td><td>Metamynodon</td><td>United States</td><td>Texas</td><td>Wall (1998)</td></tr><tr><td></td><td>Zaisanamynodon</td><td>United States</td><td>Oregon</td><td>Lucas (2006)</td></tr><tr><td></td><td></td><td>Russia</td><td>Artyom</td><td>Gromova (1960); Lucas (2006)</td></tr><tr><td></td><td>Other</td><td>China</td><td>Baise Basin, Guangxi</td><td>Russell & Zhai (1987)</td></tr><tr><td></td><td></td><td></td><td>Lijiang Basin, Yunnan Province</td><td>Russell & Zhai (1987)</td></tr><tr><td></td><td></td><td></td><td>Xichuan Basin, Henan Province</td><td></td></tr><tr><td></td><td></td><td></td><td>Camp Margetts Area, Inner Mongolia</td><td>Wall & Manning (1986)</td></tr><tr><td></td><td></td><td></td><td>Liankan, Turpan Basin, Xinjiang</td><td>Russell & Zhai (1987)</td></tr><tr><td></td><td></td><td></td><td>Uygur</td><td></td></tr><tr><td></td><td></td><td></td><td>Mengjiapo, Lushi Basin, Henan</td><td>Chow & Xu (1965); Russell & Zhai (1987)</td></tr><tr><td></td><td></td><td></td><td>Province</td><td>Xu (1966); Russell & Zhai (1987)</td></tr><tr><td></td><td></td><td></td><td>North Mesa, Ulan Shireh, Inner Mongolia</td><td></td></tr><tr><td></td><td></td><td></td><td>Rencun, Henan Province</td><td>Huang & Wang (2001)</td></tr><tr><td></td><td></td><td></td><td>Tongbai, Wucheng Basin, Henan</td><td>Russell & Zhai (1987)</td></tr><tr><td></td><td></td><td></td><td>Province</td><td></td></tr><tr><td></td><td></td><td></td><td>Weinan, Shaanxi Province</td><td>Li (2003)</td></tr><tr><td></td><td>Kazakhstan</td><td>Kyzyl Murun</td><td></td><td>Lucas & Emry (2001)</td></tr><tr><td></td><td>Kyrgyzstan</td><td>Andarak 2</td><td></td><td>Averianov & Godinot (2005)</td></tr><tr><td></td><td>Myanmar</td><td>Mogaung + Myaing</td><td></td><td>Colbert (1938); Russell & Zhai (1987)</td></tr><tr><td></td><td>United States</td><td>Montana</td><td></td><td>Wall (1998)</td></tr><tr><td></td><td></td><td>Utah</td><td></td><td></td></tr></tbody></table>