# Giant longirostrine crocodylians from the Lower Miocene of Pakistan: new material and taxonomic review.

Erwan Courville, Grégoire Métais, Pierre-olivier Antoine, Laurent Marivaux, Stéphane Jouve

► To cite this version:

Erwan Courville, Grégoire Métais, Pierre-olivier Antoine, Laurent Marivaux, Stéphane Jouve. Giant longirostrine crocodylians from the Lower Miocene of Pakistan: new material and taxonomic review. Papers in Palaeontology, 2025, 11 (3), pp.e70010. 10.1002/spp2.70010. hal-05071225

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1 Giant longirostrine crocodylians from the Early Miocene of Pakistan: new material and

2 taxonomical review.

3

4 by Erwan Courville¹, Grégoire Métais², Pierre-Olivier Antoine³, Laurent Marivaux³, Stéphane

5 Jouve²*

6

7 ¹Biogéosciences, UMR 6282 CNRS, Université Bourgogne Europe, 6 Boulevard Gabriel, 21000

8 Dijon, France

9 ²CR2P, Sorbonne Université, CNRS-MNHN-Sorbonne Université, 4 Place Jussieu, 75005 Paris,

10 France

11 ³Institut des Sciences de l'Évolution de Montpellier, UMR 5554, Univ Montpellier, CNRS, IRD,

12 34095 Montpellier, France

13

14 *Corresponding author

15

16
**Abstract:** This study, based on previously undescribed crocodylian remains from the Early Miocene of the Bugti Hills (Balochistan, Pakistan), reveals the existence of at least three distinct species. It confirms the validity of the species initially identified as 'Gavialis' *pachyrhynchus*, establishing it as the sister taxon to the massive Miocene crocodylian *Rhamphosuchus crassidens*. Consequently, it is reclassified as *Rhamphosuchus pachyrhynchus*. Additionally, "Gharialis" *curvirostris* is now acknowledged as a valid species under the new genus name *Pseudogavialis*, closely related to *Gavialis*. Another set of remains represents a third species, although the poor preservation hinders precise identification.

The phylogenetic relationships between *Tomistoma* and *Gavialis* is one of the most debated issues in crocodylian phylogeny. Molecular analyses suggest a sister-taxa relationship dating back to the Early Miocene, while morphological analyses place *Gavialis* at the base of the tree, diverging from 'thoracosaurs', with a Gavialoidea/Crocodyloidea split in the Cretaceous. The inclusion of newly described species in phylogenetic analyses yields variable outcomes, highlighting the sensitivity of results to the species considered. The insertion of *Portugalosuchus azenhae*, found as a 'thoracosaur', aligns with traditional morphological findings, while the inclusion of Indo-Pakistani species of *Rhamphosuchus* supports the molecular hypothesis. Nevertheless, when the molecular result is found, a large number of morphologic gavialoids and 'thoracosaurs' makes the result strongly stratigraphically incongruent. The inclusion of fossil species in the phylogenetic analyses significantly impacts the understanding of crocodylian relationships. Even when molecular results align with morphological data, the persistent stratigraphic incongruence does not resolve the *Gavialis-Tomistoma* dilemma.

**Key words:** Bugti Hills, Pakistan, Gavialoidea; Tomistominae, *Rhamphosuchus*, phylogeny.
41 **Introduction**

42 On the Indian subcontinent, two geographical areas have been famous since the 19th
century for their rich Cenozoic vertebrate fauna: the foothills of the Himalaya in northern
43 Pakistan and India also known as the Siwalik Hills, and the Bugti Hills which forms the southern
44 rim of the Sulaiman Range (i.e., Sulaiman Lobe) in eastern Balochistan (Pakistan; Fig. 1). First
45 documented fossils from the Siwalik Hills were discovered in the early 19th century by an
46 engineer who supervised the installation of an irrigation canal in northern India, Captain Proby
47 Cautley (biography published by Brown, 1980), who was collaborating with Dr. Hugh Falconer,
48 a naturalist (Murchinson 1868). Over a few decades they collected the largest collection of
49 fossils from the Siwalik Hills, which was deposited in the collections of the British Museum,
50 London, in 1846 (Chabrol et al. 2024).
51

52 Fig. 1

53 Vickary (1846) first reported fossil vertebrates from the Kumbi area in the Bugti Hills.
54 Subsequently several campaigns collecting in the Bugti Hills were organized by members of
55 the Geological Survey of India, including Richard Lydekker (1886) and Guy Ellcock Pilgrim
56 (1907-1908). In 1909 and 1910 Sir Clive Foster Cooper from the Cambridge Sedgwick Museum
57 organized field campaigns in the Bugti area and brought to light the famous remains of
58 *Baluchitherium* (Forster-Cooper 1911). It was not until the 1990's that the field campaigns in
59 the Bugti Hills led by J.-L. Welcomme and L. Ginsburg restarted with methodological collecting
60 in a precise stratigraphic framework (Welcomme & Ginsburg 1997). In many cases, the old
61 collections from the 19th and early 20th century suffer from a lack of stratigraphical
62 information, making it difficult to determine whether the fossil was collected from the
63 Oligocene or Miocene part of the thick Bugti sedimentary sequence. The fossil material
64 reported here was collected in Kumbi, a fossil locality mentioned by Pilgrim (1908, 1912) and
situated on the northern flank of the Zin-Koh Anticline (Zin range; Fig. 1). Both Oligocene and Miocene fossil-bearing beds are exposed at Kumbi, and all the fossils collected by J.-L. Welcomme and L. Ginsburg were from the uppermost Chitarwata Formation, Early Miocene in age (Welcomme et al. 2001; Métais et al. 2009; Antoine et al. 2013), except one collected from DB-0, the stratigraphically lowermost Oligocene beds in the Bugti Hills (Welcomme et al. 2001).

Pilgrim (1908, 1912) reported skull fragments referred to *Gavialis*, and erected a new species of *Crocodilus* (*C. bugtiense* Pilgrim, 1908), but except for the latter species, their precise stratigraphic provenance was not indicated. He considered *C. bugtiensis* as found in the lowest stratigraphic levels only (Oligocene), but that no restricted stratigraphic distribution can be provided for the other species he described. So, the material described by Pilgrim is considered as Oligo-Miocene (Rupelian-Aquitanian), and no more precise age can be provided for the species erected by Pilgrim until the material collected by Welcomme and L. Ginsburg with clear stratigraphic location is completely revised.

Since Pilgrim, the crocodylians of the Bugti Hills have regrettably not generated any particular interest among paleontologists, and it is only recently that the numerous remains have attracted attention. Martin *et al.* (2019a) proposed to erect the genus *Astorgosuchus* for *C. bugtiense* Pilgrim, 1908 partly based on material collected from the stratigraphic level J1 (Welcomme *et al.* 2001) and Chabrol *et al.* (2024) reviewed the species *Crocodylus palaeindicus* Falconer & Walker, 1859.

Several longirostrine species from Pakistan were described in the late 19th and early 20th centuries, all attributed to the genus *Gavialis*, under various misspelled names ("Gharialis", "Garialis"). Lydekker (1886) erected two new species of "Gharialis": "Gharialis pachyrhynchus" Lydekker, 1886 and "Gharialis curvirostris" Lydekker, 1886. Fossil remains
documenting *'Gavialis' pachyrhynchus* were collected from two localities, "Laki Hills and Sehwan", and consist of an anterior portion of a snout preserving the naris (holotype, GSI (IM) E30; Fig. 2), an anterior portion of maxillae, and a tooth crown with an origin no more precise than "Lower Siwalik of Sindh". Martin (2019) suggested the possible close affinities between 'G.' *pachyrhynchus* and the Indian tomistomine *Rhamphosuchus crassidens* (Cautley & Falconer, 1840). "*Gharialis* curvirostris is based on a specimen from Laki Hills (Lydekker 1886), which consists of an anterior portion of a skull, preserving the posterior margin of the orbits, and divided in two parts. Three other specimens were latter described by Pilgrim (1912) and attributed to the variety "*Garialis* curvirostris var. *gajensis* Pilgrim, 1912, collected from the Gaj of Kumbi after Pilgrim, in the Bugti Hills. The material is an almost complete snout preserving the anterior margins of the orbits, a damaged posterior portion of a skull from the anterior margins of the orbits, and a mandibular symphysis. Piras & Kotsakis (2005) described another specimen from the Early Miocene of Pakistan as possibly referrable to 'Gavialis' *curvirostris*. Martin (2019) in his review suggested that 'G.' *curvirostris* and 'G.' *curvirostris* var. *gajensis* are synonym with *Rhamphosuchus crassidens* or is a possible new tomistomine species. A last species, "*Garialis* breviceps Pilgrim, 1912 was described from the "Gaj of Kumbi" by Pilgrim (1912). It consists of an almost complete snout and a mandibular symphysis previously attributed to 'G.' *curvirostris* (Pilgrim, 1908). Martin (2019) noted that two different rostra were figured by Pilgrim in three figures, but all represent the same individual from different views. He suggested a possible attribution of *Gavialis breviceps* to *R. crassidens*, or to a new tomistomine species. Finally, he concluded that all the species described by Lydekker and Pilgrim cannot be attributed to the genus *Gavialis*.

Schleich (in Corvinus & Schleich 1994) briefly described new material of *R. crassidens* from Nepal, and Srivastava & Schleich (2018) tentatively provided a review of this material
with those from the Neogene of the Indian Subcontinent. If they provided new descriptions, they did not really re-evaluate the validity of the species, and considered 'G.' *curvirostris* and 'G.' *curvirostris gajensis* as gavialids, without questioning their generic attributions, and *R. crassidens* as a tomistomines. They did not really review *G. breviceps*, but considered *G. pachyrhynchus* as a junior synonym to *R. crassidens*. More recently, Vélez (2024) erected a new name for an Eocene Pakistanis gavialoid, but «species name» is *nomen nudum* due to invalid publication as part of an unpublished PhD thesis, without ZooBank record, following the ICZN (Chapter 3, Art. 8.5).

Fig. 2

The aim of the present study is to report unpublished fossil material of Crocodylia collected in the 1990's and 2000's from lower Miocene beds in the Bugti Hills (Balochistan, Pakistan). We will discuss the taxonomic attribution of certain taxa from Pakistan of the genus *Gavialis*, such as 'G.' *pachyrhynchus*, 'G.' *curvirostris*, *G. breviceps* or *Rhamphosuchus crassidens*, which is particularly debated in the literature (Lydekker 1886; Pilgrim 1912; Martin 2019). These species have been successively considered as gavialoids or tomistomines, and the relationships between both groups is one of the most debated issues of crocodylian phylogeny in recent decades. Molecular analyses suggest a sister-taxa relationship between *Gavialis* and *Tomistoma*, the gavialoids being sister taxon to crocodyloids, while morphological analyses place the genus *Gavialis* at the base of Crocodylia, including 'thoracosaurs', the tomistomines are much more derived and included in Crocodyloidea (Brochu 2003; Oaks 2011; Shirley et al. 2014; Jouve et al. 2017). Morphological analyses assume an age of divergence between Gavialoidea / Crocodyloidea in the Cretaceous. This gharial-tomistoma issue has been recently more deeply explored and some analyses using only morphological data found results more similar to molecular analyses, but most of them used implied-
weighting and Bayesian tip-dating methods or molecular results as backbone (Lee & Yates 2018; Groh et al. 2019; Iijima et al. 2022; Walter et al. 2022; Darlim et al. 2022; Salas-Gismondi et al. 2022; Massonne et al. 2022). Nevertheless, some other using parsimony method with unweighted and unconstrained morphological data found results close to those found in molecular analyses (Rio & Mannion 2021; Ristevski et al. 2020, 2022, 2023; Puértolas-Pascual et al. 2023). Nevertheless, even when the *Gavialis*—*Tomistoma* relationships is congruent with molecular analyses, the result remains strongly incongruent with the age of divergence between *Gavialis* and *Tomistoma* proposed by these analyses. This is due to the Late Cretaceous—Paleogene ‘thoracosaurs’, found as more closely related to *Gavialis*.

The age of the species described herein, Early Miocene, falls during a period of diversification of crocodylians and corresponds to the *Tomistoma/Gavialis* divergence age according to molecular phylogenetic analyses (Brochu 2003; Oaks 2011; Shirley et al. 2014; 58).

Although abundant, the fossil crocodylians from the Bugti Hills described in the literature come mainly from collections made in the late 19th century. The geographical and stratigraphical provenance of these fossils has proven to be elusive (i.e., imprecise or even unknown). On the other hand, the material described in this study was collected in a controlled stratigraphic context, enabling more precise dating of material published in the last century, and could be serve as a reference point for further studies.

## GEOLOGICAL AND STRATIGRAPHICAL CONTEXTS

The fossil material studied here comes from the Kumbi locality, in the eponymous section situated along the northern margin of the Zin-Koh Anticline in the Bugti Hills. This
region is located on the southern rim of the Sulaiman Range (Sulaiman lobe), northeast of Balochistan (Pakistan; Fig. 1A, B). The sedimentary series exposed in the Bugti area records the transition from an Eocene marine depositional environment to a fluvial continental environment related to the early establishment of a 'Proto-Indus', which drained the early Himalayan foothills during the Paleogene (Welcomme et al. 2001; Métais et al. 2009; Roddaz et al. 2011).

At Kumbi, the base of the continental sedimentary sequence is represented by the Chitarwata Formation (Welcomme et al. 2001) including at its base the Bugti Member ranging from the Oligocene up to the Early Miocene (Fig. 1C). The fossils reported in this work come from the level 4 which lays near the top of the Chitarwata Formation (Welcomme et al. 2001; Métais et al. 2009; Antoine et al. 2013). The base of the Chitarwata Fm. unconformably overlies the middle Eocene Habib Rahi limestone at Kumbi. The level 0 designates the ferruginous duricrust that rests unconformably on the marine units of the Kirthar Group and is considered as early Oligocene in age (Welcomme et al. 2001; Métais et al. 2009).

In the Bugti Hills, the sedimentary facies of the upper Chitarwata Fm. Indicate a fluvio-deltaic drainage network and a vast floodplain (Welcomme et al. 2001) which is consistent with the establishment of the sedimentary basin and the current drainage system of the Indus (Métais et al. 2009). The upper Chitarwata Fm. consists mainly of sandy deposits with little induration, as well as to sandstones and microconglomerates. In the Bugti Hills, the uppermost Chitarwata Fm. documented by the level 4 has yielded the most diverse fauna of the Bugti Hills (Assemblage A, Aquitanian, ca. 21.5 Ma; Antoine et al. 2013). Fossils of large vertebrates come mainly from lateritic levels rich in iron oxides (levels 0 to 6, Fig. 1C; Métais et al. 2009).

No clear sedimentary discontinuity has been observed between the uppermost Chitarwata Fm. (level 4) and the overlying Vihowa Fm. (levels 5 and 6) which has yielded a fauna
185 ("Assemblage B" in Antoine *et al.* 2013) equivalent to the Kamlial fauna of the Siwalik Hills.
186 The base of the Kamlial Fm. in the Siwaliks has been correlated with the biozone MN3 in
187 Europe (ca. 19 Ma; Antoine *et al.* 2013). The material studied here comes from one of the
188 levels of microconglomerates enriched in oxidized allochthonous quartz and feldspar (Métais
189 *et al.* 2009) resulting from the erosion of the Himalayan chain and significant fluvial transport
190 (Naseem *et al.* 2003; Roddaz *et al.* 2011).

191

192 MATERIAL AND METHODS

193

194 *Material studied*

195

196 The fossil crocodylian material of the Bugti Hills studied in this work was collected
197 during the 1995 and 1996 expeditions of the "Mission Paléontologique Française au
198 Baloutchistan" (MPFB). The material (more than 350 fragments, with more than 120 of
199 mandibles, maxillae, and premaxillae) was collected from the level 0 (Rupelian, Lower
200 Oligocene), level 4 (Aquitanian, Lower Miocene), but also from the levels 5 and 6 (Fig. 1B.;
201 Burdigalian, Lower Miocene; Welcomme *et al.* 2001). The material, although fragmentary, is
202 well preserved overall, and the studied specimens are listed in Courville *et al.* (2024, Tables 1
203 to 3). The fossils are only slightly deformed, but often embedded in compact ferruginous
204 sandstones typical of the "Bugti Bone Bed" levels (Welcomme *et al.* 2001).

205

206 *Measurements*

207
Most of the studied remains consists of isolated mandibular and maxillary fragments comprising several alveoli, making it difficult to identify them taxonomically. So, we conducted comparative measurements using a modified version of those proposed by Pilgrim (1912) in the original description of the material from Pakistan. They are the length of the maxilla from the anterior margin of the first maxillary alveoli to the posterior margin of the third (L3), and the width of the maxilla at the level of the fourth (W4). If the second measurement quantifies the variation in the snout width, the first is problematic as it is related to the size of the alveoli and to the interalveolar distance. To increase the number of data points, measurements were taken on dentary lengths from the fifth to the eight and the width at the level of the eight when available. As the lateral margins of the dentary are nearly parallel and the distance between the teeth and their size are constant in numerous specimens, the measurements have also been conducted when the exact position of the teeth was not known, but only on the teeth anterior to the anterior extents of the splenial (Courville *et al.* 2024, Table 2).

The diameter of the maxillary and dentary alveoli according to the adjacent maxillary and dentary width has also been considered. In order to tentatively minimise the impact of the variation in size of the maxillary and dentary alveoli and in mandibular and maxillary width, only the alveoli posterior to the fourth dentary and third maxillary alveoli have been considered (Courville *et al.* 2024, Table 3). Measurements on the studied material were performed using a digital caliper. The various measurements on the comparison material were carried out using the data available in the literature and using ImageJ version 1.52 software (Schindelin *et al.* 2012).

229

230 *Size estimation*

231
The size of one of the revised species was estimated using linear regressions of skull size whilst respecting the total size of the specimens previously used to estimate the total body length of *Sarcosuchus imperator* Broin & Taquet, 1966 (Sereno *et al.* 2001). The skull length of *R. pachyrhynchus* was estimated from the width of the premaxillae of *S. imperator* and *Crocodylus porosus* Schneider, 1801, as well as from the width of the maxilla of *S. imperator*, its premaxilla being particularly enlarged (Courville *et al.* 2024, Appendix S1). The measurements used are presented in Courville *et al.* 2024 (Appendix S1).

*Sarcosuchus imperator*, a longirostral taxon, displays cranial proportions comparable to those observed in *R. pachyrhynchus*, despite not being part of the Crocodylia group. *Sarcosuchus imperator* demonstrates similarities to *Rhamphosuchus* in terms of a more durophagous dental morphology, with large robust and closely spaced teeth (Sereno *et al.* 2001; Lydekker 1886), standing out in a group where most taxa are predominantly piscivorous with long and narrow snout and slender and widely spaced teeth such as in *G. gangeticus*. Both species exhibit comparable adaptations, including reduced interdental space and larger teeth. As only the anterior part of *R. pachyrhynchus*'s rostrum is preserved, the length estimation of its skull was based on the maximum width of the premaxilla for *C. porosus*, and the combined width of the premaxilla and maxilla (given the significantly dilated premaxilla of *S. imperator*) for *S. imperator* (measurements in Tables 1-4; Courville *et al.* 2024, Appendix S1). Only large remains, considered as adult specimens, were used, as the significant influence of ontogeny on body proportions has already been acknowledged (Paiva *et al.* 2022).

## Taxonomic background

In morphological phylogenetic context, Gavialoidea includes *Gavialis gangeticus* (Gmelin, 1789) and 'thoracosaurs', and *Tomistoma schlegelii* Müller, 1838 is distantly related
and successively included in Tomistominae, Crocodylidae, Crocodyloidea, and Brevirostres (Brochu 2003). The age of divergence between *T. schlegelii* and *G. gangeticus* is at least Cenomanian. In molecular phylogenetic context, *G. gangeticus* and *T. schlegelii* are closely related, such as Tomistominae is included in Gavialidae with 'thoracosaurs', Gavialoidea including all species considered as Tomistominae and Gavialoidea in morphological context (Rio & Mannion 2021). The age of divergence remains at least Cenomanian, when divergence ages provided by molecular analyses are Late Oligocene – Early Miocene age (Brochu 2003; Oaks 2011; Shirley et al. 2014).

Thus, the *Gavialis*—*Tomistoma* problem induces taxonomic and nomenclatural divergences between what is included in the groups according to the molecular or morphological context. As the main result obtained here is congruent with the classical morphological result, we used this context as the phylogenetic background, comparing our results and relationships in this context. Gavialoids include the 'thoracosaurs', and exclude tomistomines.

## Phylogenetic analysis

The matrix used in this work is that used by Jouve (2016). It is largely based on the matrix proposed by Brochu (1997a, b, 1999) and modified among others by Delfino et al. (2008), Brochu & Storrs (2012), Jouve et al. (2015, 2008, 2017), Salas-Gismondi et al. (2016, 2018, 2022), Groh et al. (2020), Iijima & Kobayashi (2019), and Rio & Mannion (2021). It comprises six new characters, and numerous others have been reworked (Courville et al. 2024, Appendix S2). The coding of the matrix has been strongly emended and 15 species added. It has been modified here using Mesquite software version 3.70 (Maddison & Maddison 2021). It includes 81 taxa including an extra-group, *Bernissartia fagesii* Dollo, 1883, and 289 morphological characters (Courville et al. 2024, Appendices S2, S3). This study focusing on
Gavialoidea and Tomistominae, 11 intragroup taxa were added compared to the matrix of Jouve (2016). Seven Tomistominae described or revised in recent years in the literature were included: *Maomingosuchus petrolica* (Yeh, 1958), coded by Shan *et al.* (2017), *Maomingosuchus* sp. coded by Martin *et al.* (2019b), *Hanyusuchus sinensis* Iijima *et al.* 2022, *Melitosaurus champsoides* Owen, 1849, "*Tomistoma*" gaudensis (Hulke, 1871), and "*Tomistoma*" calaritanum Capellini, 1890 recently reviewed by Nicholl *et al.* (2020), and *Rhamphosuchus crassidens* based on personal observations. *Portugalosuchus azenhae* Mateus, Puértolas-Pascual, Callapez, 2019, and the three species reviewed in the present paper have also been introduced.

Historically, characters in this matrix have always been treated with equal weight and unordered multistate characters (e.g., Jouve *et al.* 2015; Wu *et al.* 2018; Martin *et al.* 2019b).

51 of the 90 multistate characters were treated in an orderly fashion because their states represent a potential series of transformations (Brazeau 2011; Courville *et al.* 2024, Appendix S3).

To test the robustness of the result, we analysed several datasets including or excluding some taxon. We thus first test the new matrix including the species revised in the present paper (*Rhamphosuchus* spp., *Pseudogavialis curvirostris*)(EW-1) and, as they have various location in the trees obtained with this first analysis, when *Rhamphosuchus* spp. are excluded (EW-3, EW-4). As the ‘thoracosaurs’ are suspected to be related to gavialoids due to homoplasy (Gatesy *et al.* 2003; Harshman *et al.* 2003; Lee & Yates 2018; Darlim *et al.* 2022), we tested the impact of their deletion in the analyses (*Thoracosaurus neocesariensis* de Kay, 1842; *Thoracosaurus isorhynchus* Pomel, 1847, *Eothoracosaurus mississippiensis* Brochu, 2004, *Eosuchus minor* (Marsh, 1870), *Eosuchus lerichei* Dollo, 1907, *Ocepesuchus eoafricanus* Jouve *et al.*, 2008, *Portugalosuchus azenhae* Mateus *et al.*, 2018)(EW-5). In particular, we
tested the exclusion of some of them independently because of they have been recently included in phylogenetic analyses and found with various relationships (*Po. azenhae*) (EW-2), or are sometimes considered as the basalmost gavialoids (*E. mississippiensis*, *Eosuchus minor*, *Eosuchus lerichei*) (EW-6, EW-7).

All the analyses in maximum parsimony were carried out with TNT V.1.5 software (Goloboff & Catalano 2016) as previously described (Young *et al.* 2016). Heuristic searches were performed with the New Search Technology Tool (NTS), with sector search, the selection size above 75 using 1,000 drifting cycles, 1,000 starts below 75 and trees were fused 1,000 times. The consensus sectorial search (CSS) and exclusive sectorial search (XSS) were set to 1,000 rounds. For ratchet, the parameters were set to stop the perturbation phase when 1,000 substitutions were made, or 99% of the swapping was completed a total of 1,000 iterations. For drift, the perturbation phase stopped when 1,000 substitutions were made, or 99% of the swapping was completed, and the number of cycles was set to 1,000, and with 1,000 additional random sequences and a TBR branch rearrangement algorithm (Young *et al.* 2016). The branches of minimum length (0) have been collapsed.

The presence of highly homoplastic characters can confuse the phylogenetic message. The *Gavialis-Tomistoma* dilemma is probably related to the presence of these homoplasies. A method, 'implied weights' (IW), has been developed to down-weight homoplastic characters during tree search (Goloboff 1993), where the constant 'k' controls the severity of the weighting (Rio & Mannion 2021). The algorithm was latter modified to better deal with the missing data (Goloboff 2014) – 'extended implied weighting' (EIW). The consistency and the ability of the method has been strongly debated (Congreve & Lamsdell 2016; O'Reilly *et al.*, 2016; Goloboff, Torres & Arias 2018; Ezcurra, 2024), but the datasets described above have also been tested with Implied weighting (IW) and extended implied weighting (EIW),
328 alternatively with constant K equal to 3 (IW3-1 to IW3-7 and EIW3-1 to EIW3-7) and 12 (IW12-1 to IW12-7 and EIW12-1 to EIW12-7) for both methods.

330 As the time of calculation is much more longer using IW and IEW, the heuristic searches were performed with the New Search Technology Tool (NTS) but with different options: with sector search, the selection size above 75 using 1,00 drifting cycles, 100 starts below 75 and trees were fused 100 times. The consensus sectorial search (CSS) and exclusive sectorial search (XSS) were set to 100 rounds. For ratchet, the parameters were set to stop the perturbation phase when 100 substitutions were made, or 99% of the swapping was completed a total of 100 iterations. For drift, the perturbation phase stopped when 100 substitutions were made, or 99% of the swapping was completed, and the number of cycles was set to 100, and with 5,000 additional random sequences and a TBR branch rearrangement algorithm.

340
341 *Institutional abbreviations*. MNHN, Museum national d'Histoire naturelle, Paris, France;
342 MHNT, Muséum d'histoire naturelle de Toulouse, France; NHMUK, Natural History Museum,
343 United Kingdom, London, United Kingdom; IM, Indian Museum, Geological Survey of India,
344 Kolkata, India.

345
346 SYSTEMATIC PALEONTOLOGY

347
348
REPTILIA Laurenti, 1768

349
CROCODYLIA Owen, 1842

350
GAVIALOIDEA Hay, 1930

351
RHAMPHOSUCHUS Cautley & Falconer, 1840
352

353

Type species. *Rhamphosuchus crassidens* (Cautley & Falconer, 1840)

354

355

*Emended diagnosis.* Very large crocodilian, exceeding 6 m in total length, with snout at least 2.5 times wider than high; maxilla with contiguous alveoli in adult specimens, whose diameter increases anteroposteriorly from the first to at least the fifth; maxilla wider than the dentary such as the dentary teeth occlude on the palatal surface medially to the maxillary tooth row; the lateral margin of the maxilla as the tooth row widen posterolaterally from the first maxillary tooth; unornamented area posterior to the naris delimited by a more or less marked crest suggesting the probable presence of a ghara as in *Gavialis gangeticus*; differs from *Pseudogavialis curvirostris* in having: the third and fourth premaxillary teeth nearly aligned anteroposteriorly; parallel to the sagittal axis; the fifth premaxillary tooth medial to the fourth; the fifth premaxillary alveoli medial to the fourth; the fourth premaxillary alveoli ventrally oriented; the first maxillary alveolus is medial to the fourth premaxillary; maxillary and dentary alveoli with margins in the same plane than the surfaces between the tooth rows; the size of the alveoli varies along the tooth row; external naris circular in shape.

356

357

358

359

360

361

362

363

364

365

366

367

368

369

### *Rhamphosuchus pachyrhynchus* (Lydekker, 1886) nov. comb.

370

Figures 2-5, 7, 8

371

1886 *Gharialis pachyrhynchus* Lydekker, pp. 227–229, pl. 23 figs 1, 1a, 1b, 4.

372

1912 *Garialis breviceps* Pilgrim, p. 82, pl. 29, figs 2–3, pl. 30 figs 1, 1a.

373

1912 *Garialis curvirostris* var. *gajensis* Pilgrim, p. 80, pl. 28.

374

375

*Holotype*. GSI (IM) E30, anterior portion of snout.
376 *Referred material.* Anterior portions of both cranial and mandibular element deposited in the
377 Indian Museum, Kolkata (syntypes of *G. breviceps*, GSI (IM) E224 and GSI (IM) E226; Fig. 3),
378 and 45 fragmentary specimens deposited in the Muséum national d'Histoire naturelle, Paris.
379 Details in Courville *et al.* (2024, Table 1).

380 *Stratum typicum.* Lower Siwalik.

381 *Locus typicus.* Laki Hills (Sindh, Pakistan).

382 *Age.* The holotype is dated from the Oligocene-Miocene, but the material referred to
383 *Rhamphosuchus pachyrhynchus* in the present study comes from the level 4 from Kumbi,
384 Shamoli (MNHN.PAK 1801, MNHN.PAK 1804), and Gandoï (MNHN.PAK 1914, MNHN.PAK
385 1915, MNHN.PAK1956b) in the Bugti Hills (Pakistan) and is dated to the end of the Aquitanian
386 (Lower Miocene).

387
388 *Emended diagnosis.* Large crocodylian reaching 6-8m in total body length, with wide and
389 rounded premaxillae, with very marked lateral extension in relation to the maxilla; an anterior
390 nasal process in dorsal view which extends between the premaxilla; maxillary alveoli row
391 curves ventrally from the first to at least the fifth in lateral view in largest specimens; largest
392 specimens bear a triangular depression between each alveolus, lateral to the tooth row; the
393 splenial extending over the length of 5-6 alveoli in the mandibular symphysis; *Rhamphosuchus*
394 *pachyrhynchus* differs from *Rhamphosuchus crassidens* in having: a premaxilla not depressed
395 anterior to the external naris; the lateral margin of the external naris in the premaxilla that is
396 much higher than the maxilla; a very large, wide, and rounded external naris.

397
398 **Description and comparison**

399 **Rostrum**
General comments. For R. pachyrhynchus, a skull length of 82-105 cm has been evaluated, based on the holotype GSI (IM) E30. The largest remains attributed to R. pachyrhynchus, suggests a size ranging from 6 to 8 m when using the premaxilla or maxilla of *Sarcosuchus imperator* as a reference and 7 m when based on *Crocodylus porosus*, making it one of the largest predators in its ecosystem. Remains attributed to R. pachyrhynchus are larger and more robust than those attributed to most Cenozoic taxa from the Bugti Hills and Siwaliks, except for two species: *Rhamphosuchus crassidens* and *Astorgosuchus bugtiensis* (Martin *et al.* 2019a).

Premaxilla. The description below is mainly based on MNHN.PAK 1914, which has the most complete and best-preserved premaxillae (Fig. 4A-E). In dorsal view, the widest part of the premaxillae measures 16.5 cm and the narrowest part, at the level of the lateral notches for the insertion of the fourth tooth, measures 10.8 cm (Fig. 4A-D). The premaxilla has five teeth, which differs from what is observed in the tomistomines *Dollosuchoides densmorei* Brochu, 2007 and *Tomistoma schlegelii* and some gavialoids (Kraus 1998; Salas-Gismondi *et al.* 2016; Souza *et al.* 2018). The presence of an additional alveolus corresponds to the second tooth of the premaxilla in *Gavialis gangeticus* (Lydekker, 1886). According to Boulenger in Mook (1921a, p.144), this tooth disappears during ontogeny in *T. schlegelii* (presence of a fifth alveolus on the premaxilla of a juvenile *T. schlegelii*, MNHN.PAK 1944-233). The absence of diastemas or the short distance between alveoli 3-4 and 4-5 (Figs 4A, B, 5A) is similar to that observed in the syntypes of *G. breviceps* (Pilgrim, 1912) and *G. pachyrhynchus* (Lydekker 1886; Martin 2019; Figs 2, 3). As observed by Martin (2019) in *G. pachyrhynchus*, these results from a less elongate premaxilla than in other taxa of the genus *Gavialis* whose premaxilla is known (*G. gangeticus*, *G. bengawanicus Dubois*, 1908) and in *T. schlegelii*. The premaxilla has a general rounded shape and is very extensive laterally, especially in specimen MNHN.PAK 1914
(Fig. 4A, B), as in the holotypes of *R. pachyrhynchus* (Lydekker 1886) and *G. breviceps* GSI (IM)
E26 (Pilgrim 1912), but contrary to that seen in *R. crassidens*. The narial opening is large and
rounded. It is as wide as long (Fig. 4A, B). Its lateral margin is high, higher than the height of
the maxilla (Figs 4E, 5C). Its posterior margin is smooth, flat and forms a posteriorly-spreading
ridge, as in *G. gangeticus*, *G. breviceps*, *G. pachyrhynchus* and *R. crassidens* (Figs 2–3; Lydekker
1886; Martin & Bellairs 1977), while the posterior margin of the narial opening is straight with
no ridge in all known tomistomines. This posterior deflection is often attributed to the
presence of a ghara (Hone et al. 2020; Martin & Bellairs 1977; Martin et al. 2012) characteristic
of the genus *Gavialis*. This ridge forms a V in the posteromedial part of the narial opening (Figs
4A, B, 5F, G), as in *G. breviceps*' syntype (Fig. 3; Pilgrim, 1912) and Siwalik *Gavialis*
(NHMUK.48461). This ridge is much lighter in male *G. gangeticus* (Hone et al. 2020) and *R.
crassidens*.

Fig. 3

Fig. 4

In ventral view, the premaxilla extends posteriorly to the third alveolus of the maxilla
(Fig. 4C, D), as in *T. schlegelii* and specimens described by Lydekker (1886). The posterior
process is shorter in most of the tomistomines (Owen 1850; Toula & Kail 1885; Swinton 1937;
Shan *et al.* 2017) but longer in all derived gavialoids, in which it extends at least to the fourth
alveolus of the maxilla (Sill 1970; Kraus 1998; Martin *et al.* 2012; Salas-Gismondi *et al.* 2016).
The maxilla-premaxilla suture participates in the medial margin of the first maxillary alveolus
(Figs 4C, D, 5H, I), a condition observed in *T. schlegelii*, most of the *G. gangeticus* specimens
(at least the largest ones) as *Gavialis* from Pakistan described by Lydekker (1886), the primitive
gavialoid *Eosuchus lerichei*, but not in *G. cf. bengawanicus*, *G. curvirostris* (MNHN.PAK 480,
MNHN.PAK 560; Lydekker, 1886; see below), and any other tomistomines and gavialoids. The
448 suture is described as running far from the alveoli margins in the holotype of *R. pachyrhynchus*
449 by Lydekker (1886) (Fig. 2), but as numerous details are erroneous (only three premaxillary
450 alveoli figured; even if the area where the two first right alveoli were probably located is
451 present, they are not figured), the figure cannot be considered with confidence, and the
452 location of the suture could be erroneously figured. On the right side the suture also runs
453 across the probable location of the first unfigured maxillary alveolus. The suture extends
454 lateromedially in a zigzag from the posterior part of the second alveolus in MNHN.PAK 1914
455 and MNHN.PAK 530 (Fig. 4C, D, K, L), whereas the shape is simply posteriorly acute in
456 specimen GSI (IM) E30 (Pilgrim, 1912; Fig. 2). The condition observed in MNHN.PAK 1914 and
457 MNHN.PAK 530 differs from *G. gangeticus* and ‘*G.* curvirostris in which the premaxilla extends
458 posteriorly in a tapered fashion, as well as *T. schlegelii* where the suture is W-shaped with a
459 single anterior medial maxillary process. The foramen incisivum is not preserved in the
460 available specimens. Two deep pits are observed between alveoli 1 and 2, and between alveoli
461 3 and 4 of the premaxilla (Fig. 4C, D). One pit is in a lateral position for the insertion of the
462 dentary tooth. The other one, in a more medial position, is pierced with several small
463 foramina, and could be related to the insertion of soft tissues with a possible sensory function.
464 Such depression is observed in *T. schlegelii* and *G. gangeticus*, and considered as an occlusal
465 pit in *G. cf. bengawanicus* by Martin *et al.* (2012), but this interpretation is probably
466 erroneous. In *G. gangeticus*, this depression extends more posteriorly even if shallower in this
467 area, reaching the level of the anterior margin of the fourth premaxillary tooth. The lateral
468 margin of the premaxilla is almost vertical and high, higher than the maxilla. This is observed
469 in syntypes of *G. breviceps'* and holotype of *R. pachyrhynchus* (Lydekker, 1886; Pilgrim, 1912),
470 but differs from *R. crassidens*, in which the lateral margin of the premaxilla is nearly as high as
471 the maxilla.
The lateral and dorsal surfaces of the premaxillae are ornamented with small pits without preferential orientation (Fig. 4A, I, J). It differs from *G. gangeticus* which has a smoother ornamentation. The ornamentation has a rougher appearance on the lateral almost part of the premaxilla (Figs 4E, H, 5C). The most anterior margin of the premaxilla, which is very straight, has an almost vertical orientation as in *G. breviceps* (Fig. 3). In dorsal view, the triple suture between the posterior part of the premaxilla, the maxilla and the anterior part of the nasal is located at the level of the sixth alveolus of the maxilla. In MNHN.PAK 1914 the nasal penetrates medially between the posterior processes of the premaxillae over several centimetres but remains distant from the narial opening (Fig. 4A, B) as in most tomistomines and gavialoids. In MNHN.PAK 530, the anterior portion of the preserved nasal seems to be particularly narrow, and its contact with the premaxillae is hard to see, but the premaxillae seem to reach at least the level of the fifth tooth (Fig. 4I, J). According to Pilgrim (1912), there is no contact between the nasal and premaxillary processes in the syntype of *G. breviceps*, but the pictures provided do not allow verification of this feature (Fig. 3). The posterior part of the premaxilla is not visible in the holotype of *G. pachyrhynchus* (Lydekker, 1886). The nasal does not seem to contact the premaxillae in *R. crassidens*. Alveoli 1, 3 and 4 of the premaxillae are large (between 2.5 and 3 cm in diameter), the fourth being the largest in some specimens (GSI (IM) E30, holotype of *G. pachyrhynchus*), or the third and fourth are the largest and of nearly same size (MNHN.PAK 1914; Fig. 4C, D). Alveoli two and five are the smallest (2 and 2.5 cm, respectively). The third and fourth alveoli are aligned with the sagittal axis or the fourth is slightly more lateral, the fifth is in a more medial position than the fourth, and the third premaxillary alveolus is more lateral than the first maxillary one (Fig. 4C, D).

No teeth are preserved on the premaxilla. More foramina related to pressure domes are observed on the anterior and lateral parts of the premaxilla (Fig. 4A, E; Fig. 5) than on the
dorsal part, as in *G. gangeticus*. This differs from *T. schlegelii* where foramina are almost
equally distributed on the dorsal and lateral parts of the premaxilla. Several foramina are
present on the ventral surface of the premaxilla, along the medial margin of the tooth-row. A
larger anteroposteriorly elongated foramen is located on the ventral surface, at the level of
the posterior margin of the fifth premaxillary tooth prolonged with a deep posterior groove
(Fo, Fig. 4K–N; MNHN.PAK 530). Such large foramina exists in other crocodylians such as
*Crocodylus niloticus* Laurenti, 1768, *Crocodylus porosus*, *Osteolaemus tetraspis* Cope, 1861,
and *Melanosuchus niger* (Spix, 1825), but located more posterior just anterior to or on the
premaxilla-maxilla suture. A large foramen located at the level of the last premaxillary tooth
is present in *Mecistops cataphractus* (Cuvier, 1825)(MNHN 1926-24), *Tomistoma schlegelii*,
and *Maomingosuchus petrolica* (Yeh 1958; Shan *et al.* 2017) and numerous crocodyloids,
whereas it is absent or small in *G. gangeticus*. A deep depression is also located more
posteriorly and more on the lateral margin than the foramen (Dp, Fig. 4L, N), crossed
posteriorly by the premaxilla-maxillary suture, and its shape and lateral position exclude that
it is an occlusal pit. Several small foramina are visible in it. Such depression is visible but
smaller in *G. gangeticus*, *Gavialis* from the Siwalik Hills (NHMUK.R39811), in *G*. cf.
*bengawanicus* (Fig. 6) but described as an occlusal pit (Martin *et al.* 2012), and maybe in *T.
schlegelii*. This structure is absent from other tomistomines and gavialoids in which it could be
observed. This could correspond to the pit described as the insertion for the third dentary
tooth described in *G. breviceps* syntype by Pilgrim (1912; Fig. 3B).

*Maxilla*. In the largest specimens, the maxillary alveoli are close together (MNHN.PAK 1914;
MNHN.PAK 898; MNHN.PAK 531; MNHN.PAK 542). The same close alveoli are observed in the
syntype of *G. breviceps* (Pilgrim, 1912; Fig. 3B), in *G. pachyrhynchus* (Lydekker, 1886; Fig. 2B),
and *R. crassidens*. The interalveolar distance in same tooth-row seems to increase on the
posterior part of the maxilla in some specimens. The ratio between the alveoli diameter and
the interalveolar distance increases with the distance between the tooth-row, and thus with
the size of the specimen considered. The teeth are close to each other in largest specimens
only (Figs 4C, D, 5E, K, M, Q, S-U). The space between the teeth can be larger in smaller
individuals (Figs 4K, L, 5D, H, I). Many studies show a high variability in the morphology of the
rostrum in Crocodyloidea, whether related to sexual dimorphism (Foth, 2012) or ontogeny
(Mook 1921b; Erickson et al. 2003; Foth 2012). *Gavialis gangeticus* also shows a reduction in
the distance between alveoli of same raw during growth. The size of the alveoli, as the
proportion of the decrease of the interalveolar distance, is probably related to the ontogeny
in *G. pachyrhynchus*. Also, the alveoli diameter increases from the first to at least the fifth
alveolus, and this increase is much more marked in the largest specimens (Fig. 4C, D, K, L). This
is also observed in *G. breviceps* (GSI (IM) E226; Pilgrim 1912; Fig. 3B) and *T. schlegelii*. The size
of the maxillary teeth also varies along the tooth row in *R. crassidens*. This variation in the
diameter of the alveoli along the maxilla is not present in *G. gangeticus* and '*G.' curvirostris
*(Pilgrim 1912; see below). As the fragmentary nature of the remains makes the comparison
difficult, Pilgrim (1912) measured the length between the anterior margin of the first 3
maxillary alveoli and the posterior margin of the third one (L3). He compared these
measurements with the width of the maxilla at the level of the fourth maxillary tooth (W4).
On the syntype of *G. breviceps* (GSI (IM) E226) the length L3 is less than half the width of the
maxilla at the fourth alveolus, and thus differs from '*G.' curvirostris, G. gangeticus, G. lewisi
*Lull, 1944* and *T. schlegelii* for which this value is equivalent to almost the entire width of the
maxilla. This reflects a wider and more robust snout in large *G. pachyrhynchus* than in these
longirostrine forms. In lateral view, the maxillary alveoli row curves ventrally from the first
maxillary to at least the fifth in the largest specimens (Fig. 4E). This condition is absent in *G*.
544 *gangeticus*, 'G.' *curvirostris*, *R. crassidens*, and most of the gavialoids and tomistomines in
545 which the margin is linear in lateral view. In *T. schlegelii*, *Maomingosuchus petrolica*,
546 *Tomistoma lusitanica* Antunes, 1961, *Toyotamaphimeia machikanense* (Kobatake et al.,
547 1965), and *Penghusuchus pani* Shan et al., 2009 the curvature is light. It is stronger in basal
548 tomistomines. This difference could be related to the variation in the tooth sizes, increasing
549 to at least the fifth in the species with ventral maxillary curvature. *Rhamphosuchus crassidens*
550 is an exception, as its tooth alveoli vary in size, and the ventral margin is linear, but contrary
551 to the other species in which the alveolar size varies, the margins of the alveoli are raised with
552 the palatal surface.

553 Pits are observed between each alveolus for the insertion of the dentary teeth in a
554 more medial position than in *T. schlegelii* (Figs 4C, D, K, L-N, 5K, M, Q, S, T) which implies a
555 dentary less wide than the maxilla, as in *R. crassidens* (Lydekker 1886), and the maxillary and
556 dentary teeth do not interlock. On the posterior part of the maxilla, the presence of a marked
557 edge, lateral to the alveoli, the proximity of the alveoli to each other and the well-developed
558 lateral edge of the maxilla, form a triangular fossa between each alveolus laterally (Figs 4K-N,
559 5H, I, M, S, T). The proximity between the alveoli as well as this typical structure of the maxilla
560 differs from the observations made in *G. gangeticus*, *G. lewisi*, 'G.' *curvirostris*, *G. hysudricus*
561 Lydekker, 1886 and *T. schlegelii*. The presence of two triangular depression is observed in the
562 largest specimens, with teeth that are close to each other. It is possible that they are due to
563 the increase in size of the alveoli and decrease of the interalveolar distance. Also, in smaller
564 specimens in which the alveoli are not close, both depressions exist sometime, and are
565 separated by a crest. In the anterior part, the rapid spreading of the lateral edges of the maxilla
566 suggests a mesorostrine or even brevirostrine specimen (GSI (IM) E226). The ornamentation
567 of the maxilla differs from the premaxilla by the presence of small depressions with no
preferential orientation and no rough appearance (Fig. 4A, B). On the lateral part of the maxilla, many large foramina are arranged in line (Figs 4E, 5J, L), as seen on the posterior part of the maxilla of *T. schlegelii*. In *G. gangeticus*, these foramina are also more numerous on the lateral part of the maxilla but are more scattered and smaller in size.

There are at least nine maxillary alveoli in the maxilla, but the presence of 20 dentary alveoli (Pilgrim 1912) suggest that this number was probably equal, or higher. This number is of at least 13 in *R. crassidens*, but the unpreserved posterior part of the maxilla suggests the presence of at least four to five more teeth.

*Posterior part of skull.* Two fragments of posterior part of maxilla with closely spaced alveoli could be attributed to *R. pachyrhynchus* (Fig. 5N–P, R–T). The maxilla is short posterior to the tooth-row, being slightly longer than the length of an alveolus, and remains far from the posterior margin of the ectopterygoid. Part of the ectopterygoid is preserved. It bears a short anterior process along the medial margin of the maxilla in the suborbital fenestra and reaches the level of the anterior margin of the penultimate alveoli, as in *T. schlegelii*, but this process is much longer in *G. gangeticus*, *Gavialis* sp., and South American gavialoids (Martin *et al.* 2012; Salas-Gismondi *et al.* 2018). Contrary to what occurs in *G. gangeticus*, the posterior suture of the ectopterygoid with the jugal curves gently posteriorly and does not display a posterior process on the medial surface of the posterior ramus of the jugal (Fig. 5S, T). The jugal forms the ventral margin of the orbit. It seems to have been oval in cross section below the orbit, higher than wide, and the ventral margin of the orbits seems to gently curves in lateral view (Fig. 5R, N), with no "step" as observed in *Gavialis*. The lateral surface of the jugal is relatively densely ornamented with deep pits, while the posterior portion of the maxilla is relatively smooth, as in *Tomistoma*.

Fig. 5
592 Fig. 6

593 *Mandible*. The lateral extension of the anterior part of the mandibular symphysis is not
594 marked (Fig. 7A) as in *G. breviceps* (GSI (IM) E224; Fig. 3), that Srivastava & Schleich (2018)
595 wrongly associated to ‘*G.*’ *curvirostris gajensis*, and most tomistomines and differs in this
596 aspect from that is observed in most derived gavialoids. The symphysis is almost three times
597 wider than high, which differs from tomistomines, in which the mandible is most of the time
598 relatively narrow, contrary to the wide and flat symphysis of derived gavialoids. The ventral
599 surface is curved anteromedially and has a strong ornamentation similar to that of the maxilla.

600 The splenial participates anteriorly in the formation of the mandibular symphysis and extends
601 over the length of 5-6 alveoli, that is short (Figs 7, 8), as observed in tomistomines. In *R.*
602 *crassidens* the splenials extend over the length of seven alveoli. On the contrary, the
603 participation of the splenial in the symphysis is much longer in gavialoids, such as in *G.*
604 *gangeticus*, *G. bengawanicus*, in which the splenial extends anteriorly over 10 alveoli (Martin
605 et al. 2012). Pilgrim (1912) described the presence of 20 dentary teeth in GSI (IM) E224
606 previously attributed to *Gavialis breviceps*, and the extension of the symphysis over the length
607 of 15 alveoli (Fig. 3C). This consistently differs from what is observed in derived gavialoids in
608 which the symphysis is much more extended, its posterior limit often exceeding the level of
609 the 20th dentary tooth. In MNHN.PAK 719 the splenial, not preserved, seems to have reached
610 anteriorly the level of the 9-10th alveoli, but have stopped more posteriorly ventrally (Fig. 7F,
611 G). The splenial stops anteriorly at the level of the tenth alveoli in *T. schlegelii*, but more
612 posteriorly in gavialoids.

613 Fig. 7

614 Fig. 8
The alveoli are closely spaced in large specimens (Fig. 7A, D, H, I), but the distance between the alveoli is larger in small ones (Figs 7B, E, F, 8A). As for the maxilla, the distance between the alveoli seems to decrease ontogenetically, related to the increase of the teeth size. In a large specimen, the third and fourth alveoli are close, the distance between the fourth and five is short, that is not observed in tomistomines and gavialoids. The lateral margin of the mandible is marked with notches between alveoli, and the mandibular tooth rows are not parallel but diverge laterally posterior to the third dentary tooth (MNHN.PAK 719; Fig. 7B-G). Two teeth are preserved in an anatomical position in the rock on specimen MNHN.PAK 549. They are elongated and strongly striated, but only the upper parts of the crowns are visible.

MNHN.PAK 553 is a posterior portion of a mandibular ramus exhibiting the seven posteriormost alveoli (Fig. 7H, I). The specimen is large, and the alveoli are closely spaced. They are circular, and their diameter does not vary, only the latest being slightly smaller. The splenial is close to the alveoli but does not participate in their medial margins. The surangular reaches the posteriormost alveolus but does not seem to abut its posterior margin. It displays a short anteromedial process between the last alveolus and the splenial. This process is present in *T. schlegelii*, *T. machikanense*, and *G. gangeticus*, but much longer, being on the length of two alveoli in the two first species and four alveoli in the second species.

*Rhamphosuchus cf. pachyrhynchus*

Figures 9, 10

*Referred material.* GSI (IM) E29, an anterior portion of snout lacking the premaxillae and probably the first maxillary alveoli; MNHN.PAK 919, an anterior portion of a mandibular symphysis.
639 Stratigraphic horizon. Level 4, Uppermost part of the Chitarwata Fm.

640 Locality. Sehwan, Sindh, and Kumbi in the Bugti Hills (Balochistan).

641 Age. Late Aquitanian (Lower Miocene).

642

643 **Description and comparison**

644 *Maxilla*. GSI (IM) E29 was first described by Lyddeker (1886) as being "Gharialis"
645 *pachyrhynchus*. It is an anterior portion of a rostrum lacking most of the premaxillae (Fig. 9).

646 The maxilla preserves six left and five right alveoli that are circular. The specimen is of nearly
647 the same size as the largest specimens of *R. pachyrhynchus*. The alveoli are more widely
648 spaced than in *R. pachyrhynchus*, being half the diameter of the adjacent alveolus, in particular
649 compared to the closely packed alveoli exhibited by large *R. pachyrhynchus* specimens. The
650 alveoli diameter seems to increase slightly compared to the variation in size observed in
651 *Rhamphosuchus*. As in *R. pachyrhynchus*, the lateral margins of the maxillae widen posteriorly.

652 Between the alveoli, some anteroposterior crests separating two depressions (one is probably
653 a pit reception for a mandibular tooth) seems to be present as in *R. pachyrhynchus*. The ventral
654 premaxilla process could have reached posteriorly the level of the fourth maxillary alveoli, but
655 as the anterior limit between premaxilla and maxilla is unknown, the alveolus could be the
656 third. When measured on the figure, the length over the three first alveoli is much higher (90
657 mm) than that observed in *R. pachyrhynchus*, even when compared to the largest specimens
658 (69 mm).

659 Fig. 9

660 As the specimen has not been observed first hand, its description is based on the figure
661 provided by Lyddeker (1886), and their reliability cannot be evaluated.
662 *Dentary*. MNHN.PAK 919 preserves the seven first anterior mandibular teeth (Fig. 10). The
663 alveoli are dorsally oriented and those posterior to the fourth are smaller than that observed
664 in *R. pachyrhynchus*.

665 Fig. 10

666 Alveoli 1 and 4 of the dentary are the largest (about 3 cm in diameter), but the first
667 seems to be larger than the fourth. The second alveolus is about 2.5 cm long and the others
668 about 2 cm. The third is the smallest, close to the fourth. The second alveolus is slightly more
669 lateral than the first, aligned with the fourth, and its anterior margin seems to be at the same
670 level as the posterior margin of the first alveolus. This organisation is nearly like what is
671 observed in *R. pachyrhynchus* (MNHN.PAK 545; Fig. 7A), but significantly differs from what is
672 observed in ‘*G.*’ *curvirostris* in which all the alveoli are widely separated (see below), the
673 second more lateral than the third, and the third more lateral than the fourth. On the contrary,
674 the distance between the alveoli is short in large specimens of *R. pachyrhynchus*, with
675 comparable general sizes, whereas this distance is larger in MNHN.PAK 919. The length
676 between the fifth and the seventh alveoli compared to the mandibular width is much higher
677 than that is observed in mandible of *R. pachyrhynchus* with similar size, as is observed in the
678 maxilla IME29 figured by Lyddekker (1886; Fig. 9), thereby suggesting that they could pertain
679 to the same species, different from *R. pachyrhynchus*.

680

681

cf. *Rhamphosuchus n. sp.*

682

Figure 11

683 *Referred material*. GSI (IM) E222, an anterior portion of snout lacking the posterior portion of
684 the skull from the anterior margin of the orbits (Pilgrim 1912).

685

**Locality:** Gaj of Kumbi in the Bugti Hills (Pakistan).
686 **Age**: Oligocène-Miocène (Rupelian-Aquitanian).

687

688 **Description and comparison**

689 *Premaxilla*. The premaxillae are slightly wider than the maxillae, with a deep lateral notch between maxilla and premaxilla (Fig. 11). This notch is deeper than in *Ps. curvirostris*. The external naris is relatively small, with its anterior margin at the level of the third premaxillary alveolus (Fig. 11), as in *G. gangeticus*, *Ps. curvirostris* and *R. crassidens*, whereas it is more anterior in *R. pachyrhynchus* and *T. schlegelii* (see above). The foramen incisivum seems to be anteroposteriorly oval, larger than in *R. crassidens* and *Ps. curvirostris* in which it is thinner as in *G. gangeticus*. The third and fourth alveoli are aligned with the sagittal axis as in *Rhamphosuchus* spp., and contrary to that is observed in *Ps. curvirostris*. Also, contrary to that is observed in the latter species, the fifth alveolus is more medial than the fourth, and lateral to the first maxillary alveolus, as in *Rhamphosuchus* spp.

699 Fig. 11

700 A depression seems to be present as the level of the lateral contact between the premaxilla and maxilla, but a direct observation is required to confirm its presence.
701
702 *Maxilla*. Pilgrim (1912) and Srivastava & Schleich (2018) described the presence of 17 maxillary alveoli in GSI (IM) E222. Their diameter seems to vary very slightly, with the first being smaller.
703
704 The size seems to increase to the 6-7th alveoli, the 8-9th are smaller, and larger posterior alveoli seem to be present (13th-14th?). Deep occlusal pits for reception of dentary teeth are present
705
706 medial to the tooth row as in *R. pachyrhynchus*. The lateral margins of the maxillae are almost parallel, but seems to slightly widen posteriorly, as in the smallest *R. pachyrhynchus* specimens, while GSI (IM) E222 is much larger.
707
708
709 *Posterior portion of snout*. GSI (IM) E222 preserves the anterior margins of the orbits, frontal and suborbital fenestrae (Pilgrim 1912; Fig. 11). The lateral margins of the maxillae diverge at the level of the 10th maxillary tooth. In palatal view, the anterior margins of the suborbital fenestrae are anterior to the anterior margin of the orbits and reach the level of the 14-15th maxillary alveoli. The anterior margin of the orbit is rounded, but not upturned, and the interorbital distance seems to have been narrow (53.8% of the snout width at the level of the fourth maxillary teeth), narrower than the snout width. These characters differ from that is observed in most derived gavialoids and in *Ps. curvirostris*, in which the orbital margins are slightly upturned and the interorbital distance wide (more than 80% the snout width).

718

719

## GAVIALOIDEA Hay, 1930

720

### PSEUDOGAVIALIS nov.

721

Lsid: zoobank.org:act:1968216C-0EFA-4E60-BE6D-98487E69606F

722

*Type species. Pseudogavialis curvirostris* (Lydekker 1886)

723

*Etymology. Pseudogavialis* means that this genus is almost *Gavialis*, resembles *Gavialis*, but

724

is not *Gavialis*.

725

*Diagnosis*. As for type and only species.

726

727

### *Pseudogavialis curvirostris* (Lydekker 1886) comb. nov.

728

Figures 12-15

729

1886 *Gharialis curvirostris* Lydekker, p. 224–226, pl. 31 figs 1–2.

730

*Holotype*. GSI (IM) E26, orbital region and anterior end of the rostrum, Indian Museum,

731

Calcutta, India.
732 *Referred material.* 1 mandibular fragment deposited in the Indian Museum, Kolkata (GSI (IM)
733 E223; Fig. 11F), and 32 fragmentary specimens deposited in the Muséum national d'histoire
734 naturelle, Paris. Details in Courville *et al.* (2024, Table 1).

735 *Stratum typicum.* Lower Siwalik.

736 *Locus typicus.* Laki Hills (Sindh, Pakistan).

737 *Age.* Oligocene – Miocene, but the new material described in the present study was collected
738 in Kumbi, Shamoli (MNHN.PAK1803, MNHN.PAK1805) and Dandô (MNHN.PAK1919,
739 MNHN.PAK1956a) in Bugti Hills (Pakistan), and is dated to the end of the Aquitanian (Lower
740 Miocene).

741 *Emended diagnosis.* Crocodylian similar in size to *G. gangeticus* (6-7min length), with: fourth
742 and fifth premaxillary alveoli almost aligned and parallel to the sagittal plane; the dorsal
743 premaxillary process reaches the level of the 7th maxillary alveolus; first maxillary aligned with
744 the fourth premaxillary alveolus; the premaxilla-maxilla suture does not cross the margin of
745 the first maxillary alveolus; differs from *G. gangeticus* in having: a rostrum strongly
746 ornamented with deep grooves and ridges; a rounded lateral margin of the premaxilla, not
747 laterally expanded; a weak nasal-premaxilla contact; a long medial anterior process of the
748 lacrimal, longer than the lateral one; differs from *Rhamphosuchus* spp. in having: the fourth
749 premaxillary alveolus medial to the third; the third premaxillary alveoli anteroventrally
750 oriented; the maxillary and dentary alveoli open laterally; the splenial extends over the length
751 of at least nine alveoli; the dentary and maxillary alveoli are homodont in size; the naris is
752 trapezoidal; the lateral margins of the maxillae are parallel; differs from *R. pachyrhynchus* in
753 having: a premaxilla not so much larger than the maxilla; more than 19 teeth anterior to the
754 posterior margin of the symphysis; the total number of mandibular alveoli is higher than 25;
755 the foramen incisivum is narrow and opens posterodorsally in the narial duct; the orbits are
756 widely separated; and differs from *Rhamphosuchus crassidens* in having a premaxilla-nasal
757 contact.

758

759 **Description and comparison**

760 **Rostrum**

761 *General comments*. The remains attributed to this taxon are similar in size to adult specimens
762 of *G. gangeticus* and *T. schlegelii*. Proportions are similar to that suggested by Srivastava &
763 Schleich (2018). The general appearance of the specimens observed here is comparable to
764 specimens of *Ps. curvirostris* (Lydekker, 1886).

765 *Premaxilla*. The holotype of *Ps. curvirostris* (GSI (IM) E26; Fig. 12) and PAK 1956a (Fig. 13G-I)
766 have their premaxillae nearly as large as the maxillae, differing from *R. pachyrhynchus* in which
767 the lateral extension of the premaxillae is marked (Lydekker, 1886; Figs. 3-4). Compared to
768 the latter species, the alveoli are more widely spaced, in particular compared to the largest
769 specimens (Fig. 4). The result is a more elongated premaxillary than in *R. pachyrhynchus*
770 described above. The narial opening is large, and the margin within the opening has a
771 trapezoidal shape, with the posterior margin being the shortest width, resembling to what is
772 observed in Thailand, Siwaliks and extant *Gavialis* and *R. crassidens* (Lydekker 1886; Martin *et
773 al.* 2012; Fig. 13G). This external naris is circular in *Rhamphosuchus*. In MNHN.PAK 1956a, a
774 low and gentle ridge forms the posterior margin of the narial opening as in the holotype of *Ps.
775 curvirostris* (Lydekker 1886). This differs from the condition observed in *Rhamphosuchus* spp.
776 in which there is a smooth area delimited by a crest. The anterior part of the premaxillae,
777 anterior to the external naris, is lower than the lateral margins, but contrary to
778 *Rhamphosuchus crassidens*, there is no smooth surface delimited by a crest. Numerous
779 foramina related to pressure domes are observed on the lateral and anterior part of the
premaxilla. The V-shaped dorsal premaxillar-maxillary suture is similar to that of *G. gangeticus*
and the holotype of *Ps. curvirostris* (Fig. 12). In dorsal view, the suture between the posterior
process of the premaxillae, maxillae and anterior process of the nasal is difficult to study on
specimen MNHN.PAK 560 but extends at least to the level of the fifth maxillary alveolus (Fig.
13N, O). In MNHN.PAK 457+458, the two maxillae, dorsal posterior processes of the
premaxillae and nasal were spaced apart during the fossilization process (Fig. 13J–M). There
is a posterior extension of the premaxillary which contacts the anterior processes of the nasals
as in *T. schlegelii*, and as such differs from the genus *Gavialis*. The dorsal process of the
premaxillae reaches posteriorly the level of the fourth preserved alveolus in MNHN.PAK
457+458, while the premaxillae processes are still very narrow at the level of the first
preserved alveoli. The lateral premaxilla/maxilla suture was thus much anterior, and the
premaxilla extends more posterior than the level of the fourth maxillary alveolus. The lacrimal
and palatine are preserved in the same specimen, at the level of the eighth preserved alveoli,
as the palatine (Fig. 13K, M), whereas it is not present at the level of the 11th maxillary alveoli
in MNHN.PAK 560 (Fig. 13O, Q). This suggests that the alveoli anterior to the level of the
anterior extend of the lacrimal and palatine are at least the 11th, and that the dorsal processes
of the premaxillae reach at least the level of the seventh maxillary alveolus. This condition is
only observed in the tomistomine *Toyotamaphimeia machikanense* (Kamei and Matsumoto,
1965) (Kobayashi et al. 2006), the South American gavialoid *Gryposuchus neogaeus*
(Burmeister, 1885) (Souza et al. 2018), and a specimen attributed to *G. cf. bengawaniscus*
(MHNT.PAL.2006.94.1). As the posterior part of the premaxillary of *Ps. curvirostris* holotype
(GSI (IM) E26) is only partially preserved, it is not possible to attest the presence of a narrow
anterior process of the nasal between the premaxillae, although Lydekker (1886) considers
that these two bones do not contact each other, but these bones are particularly narrow in
804 MNHN.PAK 560 and the premaxilla-nasal contact is not clearly visible (Fig. 13N, O), and if the
805 specimen has had been imperfectly prepared, it could have been considered as absent.

806 Fig. 12

807 Fig. 13

808 The size of the alveoli varies in the premaxilla. The second and fifth alveoli are the
809 smallest, the first is larger, but slightly smaller than the fourth and fifth that are of nearly the
810 same size (Fig. 13H, I), relative sizes also found in *R. pachyrhynchus*, *Gavialis* sp. from Thailand
811 and *Gavialis gangeticus*. As in these species, the third alveolus is anterolateroventrally
812 oriented, whereas it is more ventrally oriented in other gavialoids and tomistomines. The
813 fourth alveolus is slightly medial to the third, as in most derived gavialoids, and contrary to
814 the lined to the sagittal axis alveoli observed in *Rhamphosuchus* spp. The fifth alveolus is
815 almost lined with the fourth. In MNHN.PAK 1956a the fourth alveolus of the premaxilla
816 appears to be aligned with the first maxillary tooth, parallel to the median axis of the rostrum,
817 as observed by Lydekker (1886) on the holotype of *Ps. curvirostris* (Fig. 12) and *T. schlegelii*,
818 and contrary to what is observed in *R. pachyrhynchus*, *G. gangeticus*, and most derived
819 gavialoids. A shallow occlusal depression seems to be present in the anterior margin of the
820 concave margin of the premaxilla in the diastema between the first and second alveoli. Two
821 other pits are observed between alveoli 1 and 2 more on the ventral surface of the premaxilla,
822 and medial to the second alveolus (Figs 13H, I, 14). The anterior one is deeper and larger than
823 the posterior one, and both are pierced with several small foramina (Fig. 13H, I). They could
824 be related to the insertion of soft tissues with a possible sensory function. Such depression is
825 observed in *T. schlegelii*, *G. gangeticus* and *G. cf. bengawanicus* (Martin *et al.* 2012) (see
826 above). It extends more posteriorly even if shallower in this area in *G. gangeticus*, reaching
827 the level of the anterior margin of the fourth premaxillary tooth when it does not exceed the
828 anterior margin of the third in *Ps. curvirostris*. It thus more resembles the condition found in
829 *T. schlegelii* in which there is a single depression located as in *Ps. curvirostris*, but without the
830 second shallow posterior depression; so, *Ps. curvirostris* has an intermediate morphology
831 between *G. gangeticus* and *T. schlegelii*.

832 In MNHN.PAK 1956a, the foramen incisivum is preserved (Fig. 13H, I) and its posterior
833 margin is at the level of the third alveolus of the premaxillary as in GSI (IM) E26, whereas in *G.
834 gangeticus*, the posterior margin of the foramen incisivum almost reaches the anterior margin
835 of the fourth alveolus of the premaxilla, and the posterior margin of the second alveolus in *T.
836 schlegelii*. Considering the deletion of the second alveolus in *T. schlegelii*, the relative position
837 of the foramen incisivum is similar to that of *Ps. curvirostris*. As in *G. gangeticus*, it is narrow,
838 small, and does not pierce the premaxillae vertically but strongly posteriorly, such as the
839 external naris is not visible throughout the foramen incisivum from ventral view, but from
840 anteroventral view, contrary to what is seen in most crocodylians. It also could be the case in
841 *R. crassidens*. Due to its posterior orientation, the foramen is prolonged anteriorly by a deep
842 gutter to the margin of the first premaxillary alveoli. The last premaxillary alveolus is separated
843 from the first maxillary by a constriction and a very long diastema (Lydekker 1886; Fig. 12). A
844 large foramen can be observed at the level of this constriction (Figs 13C-F, H, I, 14B), crossed
845 by the premaxillary-maxillary suture, as in *G. gangeticus*, *T. schlegelii* and *R. pachyrhynchus*
846 (see above). This foramen is not figured by Lydekker (1886) on the holotype, and its presence
847 or absence cannot be evaluated. In ventral view, the premaxillary extends posteriorly to half
848 the length of the fourth alveolus of the maxilla in the holotype and MNHN.PAK 560 (Fig. 13P,
849 Q), as seen in *G. gangeticus*, and differs in this point from *T. schlegelii*. Contrary to what is
850 observed in *R. pachyrhynchus*, the ventral premaxilla-maxilla suture does not cross the first
851 maxillary alveolus (Figs 12D, 13C, D).
Maxilla. The lateral edges of the maxilla are almost parallel anteriorly (Figs 12, 13J-Q), as in
*G. gangeticus*, which seems to indicate a rather longirostrous specimen (Fig. 14) compared to
*R. pachyrhynchus*. The interval between the alveoli is about equal to the anteroposterior
diameter of the alveoli, as in *G. gangeticus*, and not so different from what is observed in the
smallest specimens of *R. pachyrhynchus*. As observed by Lydekker (1886) and measured by
Pilgrim (1912), the length of the first three alveoli of the maxilla (L3) is almost equal to the full
width of the maxilla at the fourth alveolus (W4; see below; Table S2) as in *G. gangeticus*, *Ps.
curvirostris* and *T. schlegelii*, which differs from *R. pachyrhynchus* described above and *R.
crassidens*. The width of the snout (W4) is higher than 75% of the length of three alveoli (L3)
in *Ps. curvirostris*, as in *G. gangeticus* and *T. schlegelii*, and lower than 75% in *Rhamphosuchus*
spp. Some occlusal pits are sometime present for the insertion of the dentary teeth, but less
numerous and smaller in diameter than in *R. pachyrhynchus*, as is described by Lydekker
(1886) in *Ps. curvirostris* holotype (Fig. 12), suggesting more acute teeth. MNHN.PAK 457+458
preserves the 13th maxillary alveoli, and the anterior margin of the suborbital fenestra is more
posterior than this alveolus (Figs 13L, M, 14B). MNHN.PAK 564 preserves the lateral margin of
the suborbital fenestra and three alveoli. So, the total number of maxillary teeth was higher
than 16. Srivastava & Schleich (2018) described the presence of 22 maxillary teeth in the
holotype of *Ps. curvirostris*, referring to their figure 33, where this number corresponds to the
total number of upper teeth, including premaxillary and maxillary teeth. So, at least 17 alveoli
were present in the maxilla. The margins of the alveoli are higher than the palatal part of the
maxilla, which is related to the absence of marked edges of the alveoli and their latero-
ventrally directed opening, as in *Gavialis gangeticus* and as described by Lydekker (1886) in
the holotype of *Ps. curvirostris*. In *Rhamphosuchus* spp. the alveoli are ventrally directed, and
the medial margin of the alveoli more in relief. The dorsal surface of the maxilla presents a
876 homogeneous ornamentation composed of elongated anteroposteriorly very marked grooves

877 (Fig. 13A, J, N), similar to those of *G. hysudricus*.

878 Fig. 14

879 *Palatine*. The anterior process of the palatine is observable on specimen PAK 457+458 (Fig.

880 13L, M). It contacts the maxilla in a V-shaped suture, as in *G. gangeticus* and *G. hysudricus*.

881 *Posterior part of the skull*. The lacrimal is observed in MNHN.PAK 458 (Fig. 13J, K). The maxilla

882 bears a posterior process in the anterior margin of the lacrimal. This trait is an apomorphy of

883 Tomistominae (Brochu 2007), found in most of them. In *Gavialis gangeticus*, this maxillary

884 process is observed between the nasal and the lacrimal, although in some specimens the

885 posterior part of the process sometimes slightly enters the lacrimal. This could be an

886 intermediate stage of this trait. The medial part of the lacrimal contacts the nasals in a linear

887 anteroposterior suture and the lateral part is sutured to the maxilla (Fig. 13J, K). Its general

888 shape is triangular.

889 On specimens MNHN.PAK 457+458 and PAK 560, the nasals extend anteriorly in long

890 and narrow processes. They are inserted medially between the posterior processes of the

891 premaxillae and reaches the level of the sixth alveolus (Fig. 13J–M). Posteriorly, the nasals

892 medially touch the maxillae and then the lacrimal in a linear suture oriented anteroposteriorly.

893 The holotype GSI (IM) E26 preserves the posterior part of the rostrum, including the

894 orbits (Fig. 12). The anterior margin of the orbit is rounded, and upturn, and the interorbital

895 distance seems to have been wide (85.8% of the snout width at the level of the fourth

896 maxillary teeth), wider than the orbit width, much wider than in *R. pachyrhynchus*. In *G.*

897 *gangeticus* the interorbital distance is larger than the snout width, as in most derived

898 gavialoids, and on the contrary the interorbital distance is short in all tomistomines. In *R.*

899 *crassidens* the interorbital distance seems to be wide.
900 *Mandible*. The lateral extension of the anterior part of the mandibular symphysis is less
901 marked, and the symphysis narrower than in *G. gangeticus* (Figs 14C, 15A) and *R. crassidens*,
902 as seen in GSI (IM) E223 and *T. schlegelii*. The lateral edge of the alveoli is very marked and
903 visible, as in *G. gangeticus*. The maxillary and dentary teeth seem to have been aligned and
904 the teeth intertwined as in *G. gangeticus*. The dentary alveoli are spaced and the dentary is as
905 wide as the maxilla as in *G. gangeticus*. As in the later species, the alveoli are
906 anterolaterodorsally oriented, whereas they are more dorsally oriented in *Rhamphosuchus*
907 spp.

908 MNHN.PAK 908 is a symphysis preserving six alveoli with no trace of the enlarged
909 fourth nor of the splenial (Fig. 15O, P). So, the splenial does not reach anteriorly the level of
910 the 10th dentary alveolus but remains posterior. In MNHN.PAK 562 + 463 the splenial
911 participates in the symphysis over the length of at least nine alveoli (Fig. 15C, D) as in *G.
912 gangeticus*. The symphysis thus extends over the length of at least 19 alveoli. The splenial
913 extends over the length of 10 alveoli in *G. hysudricus* (Lydekker 1886) and only 6 in *T. schlegelii*.
914 As the mandibular ramus MNHN.PAK 905 preserves six alveoli located posterior to the
915 symphysis (Fig. 15L-N), the total number of mandibular teeth is of at least 25. These numbers
916 consistently differ from what is seen in *Rhamphosuchus* spp. in which the symphysis is shorter
917 (over the length of 15 and 17 alveoli) with only 20-21 teeth. Considering that the number for
918 *G. curvirotris* are minimal estimations, these higher numbers compared to *Rhamphosuchus*
919 spp. are consistent with a longer snout and a more longirostrine morphology.
920 Fig. 15

921 MNHN.PAK 905 is a posterior portion of a mandibular ramus exhibiting the six
922 posteriormost alveoli (Fig. 15L-N). The specimen is large and the alveoli are spaced, separated
923 by pits for insertion of maxillary teeth. They are circular, and their diameter does not vary,
even for the latest. The splenial is close to the alveoli but does not seem to participate in their
medial margins. The surangular reaches the posteriormost alveolus but does not seem to abut
its posterior margin. It sends a short anteromedial process between the last alveolus and the
splenial. This process is present in *T. schlegelii*, *T. machikanense*, and *G. gangeticus*, but much
longer, being on the length of two alveoli in the two firsts species and four alveoli in the second
species, and it has the same length in *R. pachyrhynchus*.

930

931

932 DISCUSSION

933

934 Taxonomy

935 Rhamphosuchus pachyrhynchus

The large size and robustness of the specimens described herein, as well as the strong
lateral extension of their premaxillae, the posterior depression of the narial opening, bring the
material studied here closer to *G. pachyrhynchus* and *G. breviceps* although it was not possible
to directly observe the specimens reported for these species during this work. Srivastava &
Schleich (2018) considered *G. pachyrhynchus* as a junior synonym to *Rhamphosuchus
crassidens* (Cautley & Falconer, 1840), when Martin (2019) also relate *G. breviceps* to the same
species. Several features are common between these three species: the large size of the
remains attributed to these taxa, a dentary less wide than the maxilla such as the dentary
teeth occlude medially to the maxillary tooth row, very robust teeth, and a variation in the
diameter of the alveoli from front to back in both mandible and maxillary alveoli, the lateral
margin of the maxilla and the tooth row widens posteriorly, and largest specimens with
dentary and maxillary alveoli closely packed, and the presence of a probable ghara suggested

936

937

938

939

940

941

942

943

944

945

946

947
948 by the unornamented area posterior to the external naris and delimited by a more or less
949 marked ridge (Table 1). As shown by Martin (2019), major differences in the arrangement of
950 the premaxillary alveoli suggest that *G. pachyrhynchus* does not belong to the genus *Gavialis*,
951 but that the three species pertain at least to the same genus, *Rhamphosuchus*. However, *R.
952 crassidens* does not show strong lateral extension of the premaxillary, the splenial participates
953 in the symphysis over the length of seven teeth instead of five in *G. pachyrhynchus*, the nasal
954 does not contact the premaxilla in *R. crassidens*, the anterior margin of the external naris is
955 not depressed in *R. pachyrhynchus* nor in *G. breviceps*, and the lateral margin of the naris is
956 much higher than the maxilla in both species compared to the premaxilla as high as the maxilla
957 in *R. crassidens*. Clearly, *R. crassidens* is a different species from *R. pachyrhynchus* and *G.
958 breviceps*.

959 Pilgrim (1912) described *Gavialis breviceps* and differentiated it from *R. pachyrhynchus*
960 described earlier by Lydekker (1886) by a less laterally expended premaxilla and the presence
961 of a pit in the premaxilla for the third mandibular tooth. As *R. pachychynchus*, the syntype of
962 *G. breviceps* is of large size (even if 20% smaller), the premaxilla is very wide (with no real
difference with *R. pachyrhynchus*' holotype), the posterior margin of the external naris bears
963 a smooth area delimited by a ridge and their lateral margins are much higher than the maxilla,
964 the teeth are large, packed, increase in size from front to back, and the tooth-rows widen
965 posteriorly. The pit for the third dentary tooth observed in the premaxilla cannot be
966 considered as diagnostic and could be pathologic. Moreover, it could correspond to the
depression observed in *R. pachyrhynchus* that the premaxillary-maxillary suture crosses
967 (MNHN.PAK 530, MNHN.PAK 456; Fig. 4). So, these specimens are here attributed to a single
968 species, *Rhamphosuchus pachyrhynchus*, and *G. breviceps* is considered as a junior synonym.
969
970
Numerous symphysis and snout fragments have their alveoli much more widely spaced than in large *Rhamphosuchus* specimens, and the size of their alveoli less increases from front to back, thereby resembling to *Ps.curvirostris*. Nevertheless, the maxillary and dentary tooth rows are directed more dorsally, their tooth rows are not parallel to the sagittal axis, widening posteriorly, and the width of the snout at the level of the fourth alveolus is larger compared to the length of the three first alveoli than in *Ps. curvirostris*. The presence of an anteroposterior crest between two alveoli separating two pits is also observed in some small maxillae, as in larger *Rhamphosuchus* specimens, the probable equivalent to the triangular depressions observed on each side between the tooth alveoli in specimens with the largest teeth (Table 1; Fig. 4).

GSI (IM) E29 and MNHN.PAK 919 seem to be different from *R. pachyrhynchus*. The maxillary fragment (GSI (IM) E29) bears several similarities with *Rhamphosuchus*, in particular *R. pachyrhynchus*, such as a large size, large alveoli which the size slightly increase posteriorly, the dentary alveoli seem to have occluded medially to the maxillary tooth row, and the maxillary widens posteriorly (Table 1). Nevertheless, several characters differ from the *Rhamphosuchus* species. Even if the specimen seems to be as large as the largest *R. pachyrhynchus*, its alveoli are not closely packed, and the length of the three first observed alveoli is much higher than that observed in *Rhamphosuchus* spp., with comparable alveoli diameters. So, we considered that this specimen cannot be clearly referred to as a described *Rhamphosuchus* species and is considered as *Rhamphosuchus* cf. *pachyrhynchus*. The mandibular fragment MNHN.PAK 919 have same characteristics than GSI (IM) E29 and is thus also considered as *R. cf. pachyrhynchus*.

The anterior portion of a snout described by Patnaik *et al*. (2014) from the Lower Miocene of India strongly resembles to *R. pachyrhynchus*. If the premaxillae are less wide, the
third alveolus more lateral than the fourth, the external naris less circular and the presence of a smooth area posterior to it not clear in the specimen, numerous *R. pachyrhynchus* characters are found in KF-27 such as the closely packed maxillary alveoli that increase in diameter posteriorly, the presence of a depression anteromedial to the second premaxillary alveolus, the maxillary that widens posteriorly, and the possible presence of a depression anterior to the first maxillary alveolus, and an irregular premaxillary-maxillary ventral suture. So, this specimen is also referred to *Rhamphosuchus* cf. *pachyrhynchus*.

1002

### 1003 *Pseudogavialis curvirostris*

Many characters, including the parallel lateral sides of the maxilla and dentary, the long mandibular symphysis, the aligned fourth and fifth premaxillary alveoli, the fourth premaxillary alveolus aligned with the first maxillary alveolus, an almost constant diameter of the alveoli along the tooth-rows, a mandibular symphysis with a weak lateral extension of the dentary mentioned above correspond to the description of the snout (Lydekker 1886) and mandible (Pilgrim 1912) of *G. curvirostris* (Table 1), and allow here the attribution of this material to this species.

Lyddeker (1886) stated that *G. curvirostris* differs from *Rhamphosuchus pachyrhynchus* by the less laterally expanded premaxillae and the maxillae with parallel lateral sides. We agree with these observations and add more others. The orientation of the premaxillary alveoli strongly differs: the fourth is medial to the third, the fifth aligned anteroposteriorly with the fourth, and the first maxillary alveoli aligned with the fourth premaxillary relative to the sagittal plane. The external naris also differs in being without the posterior depression observed in *Rhamphosuchus* spp. (Table 1). This, as the shape of the premaxilla (much wider in *R. pachyrhynchus*) should be considered with caution, as this shape clearly depends on the
1019 presence of a ghara, a male anatomical particularity (Hone et al. 2020), and they could be
1020 related to sexual dimorphism. Nevertheless, numerous other characters allow to differentiate
1021 *G. curvirostris* from *Rhamphosuchus pachyrhynchus* such as the length of the snout suggested
1022 by the length of the symphysis or the larger number of alveoli, the homodonty in size, the
1023 parallel lateral sides of the maxilla and dentary, the premaxilla-maxilla suture that does not
1024 cross the first maxillary alveolus, and the large interorbital distance. The mandible is less
1025 expanded at the level of the fourth alveoli, the symphysis is much longer, and the splenial
1026 participates in it more largely than in *Rhamphosuchus* spp. (Table 1).

1027 On the contrary, many common characters with the genus *Gavialis* have been
1028 observed, including the jaw alveoli higher than the palatal part of the maxillae and directed
1029 latero-ventrally, the high number of teeth, the shape of the external nares, the homodonty,
1030 and the shape of the foramen incisivum (Table 1). The slightly lateral extension of the
1031 premaxillary in relation to the maxilla, the contact between the premaxillary and the nasal in
1032 dorsal view and a posterior process of the maxilla in the lacrimal creating a long medial
1033 lacrimal process, are features that differ from the genus *Gavialis*, and are found in
1034 Tomistominae. Martin (2019) discussed the attribution of *G. curvirostris* to the genus *Gavialis*,
1035 in particular because of the less dorsally oriented orbits than in *Gavialis*, the supratemporal
1036 fenestra smaller than the orbit, but this author considered all the specimens described by
1037 Lydekker (1886; GSI (IM) E26) and Pilgrim (1912; GSI (IM) E222, GSI (IM) E223), when the
1038 morphological observations suggest the presence of at least two species. The length of the
1039 symphysis of the mandible GSI (IM) E223 suggests a very long snout, much longer than in the
1040 snout GSI (IM) E222. So, only the holotype (GSI (IM) E26) and the mandible GSI (IM) E223 are
1041 considered as *Ps. curvirostris*, GSI (IM) E222 being a different species (see below).
Following Srivastava & Schleich (2018) and Martin (2019) we consider that the holotype of *Ps. curvirostris* differs from all known specimens assigned to species of *Gavialis*.

There is evidence of a contact between the nasal and premaxillary, the premaxilla extends to the level of the 7th maxillary tooth, and the organisation of the premaxillary alveoli differs (Table 1). Martin (2019) proposed to attribute *G. curvirostris* to *R. crassidens* or to a new tomistominae, considering some similarities in the external nares outline and premaxillary alveolar dimensions, between *G. curvirostris*, *R. pachyrhynchus* and *R. crassidens* holotypes.

He considered the differences observed as possibly related to individual or sexual variations.

The new material described here allows us to clarify the morphological observation and to distinct *G. curvirostris* from *Rhamphosuchus* spp., and to confirm the second hypothesis, considering *G. curvirostris* as a different and valid species. Moreover, if *G. curvirostris* resembles to *Gavialis*, we consider that the species currently included in *Gavialis* such as *G. bengawanicus*, *G. gangeticus*, and *G. browni* Mook, 1932, are homogeneous with strongly telescoped orbits, a particular shape of their premaxillae, the absence of contact between the premaxillae and nasal, characters absent in *Ps. curvirostris*. So, this species strongly differs from all *Gavialis* species, thereby justifying the erection of a new genus, *Pseudogavialis*.

Pilgrim (1912) attributed a posterior portion of a skull to *Garialis curvirostris* var. *gajensis* (GSI (IM) E228). If the attribution is provided in the figure caption, this specimen does not appear in the descriptive text. Unfortunately, the preserved portion does not have large common anatomical parts with the holotype, or specimens clearly attributable to *Ps. curvirostris*, and it cannot be identified with certainty. It is considered herein as *Crocodylia indet.*, awaiting direct observation and formal review.

Recently, a new tomistomine species has been described from the Late Miocene of Pakistan, *Sakhibaghoon khizari* Malkani et al. 2022. The fragment is an anterior portion of a
1066 maxilla, but the absence of dorsal posterior process of premaxillae and the occlusal pits that
1067 are lateral to the tooth-row rather suggest it is more likely a fragment of a mandibular
1068 symphysis. The distance between the alveoli, their size and their orientation, and the thin and
1069 long anterior projection of what could be the ventral process of the splenials are congruent
1070 with that is observed in *Ps. curvirostris*. Nevertheless, the fragment is too small, and its origin
1071 from another formation than the specimens described herein do not allow to provide further
1072 comparison. Also, the specimen does not bear diagnostic characters, and we consider
1073 *Sakhibaghoon khizari* as a *nomen dubium*.

1074 It could be noted that the specimen briefly described by Piras and Kotsakis (2005)
1075 resembles to the description of *G. curvirostris* provided herein and could pertain to the same
1076 species.

1077
1078 cf. *Rhamphosuchus n. sp.*

1079 Pilgrim (1912) described the anterior portion of a skull, GSI (IM) E222 (Fig. 11), as *Garialis*
1080 *curvirostris* var. *gajensis*. He differentiated this new variety from *Ps. curvirostris* (GSI (IM) E223;
1081 Fig. 12) by its orbital margin not upturned, a much wider interorbital distance and a heavier
1082 rostrum pitting. Pilgrim noted that the premaxillae do not contact the nasals, but this
1083 character must be considered with caution, as these bones at the level of their contact are
1084 such narrow that they are sometime difficult to observe on incompletely prepared specimens
1085 we observed. We agree that this specimen has several common characters with *Ps.
1086 curvirostris*, such as a narrow premaxilla, small naris with a thick anterior margin, low
1087 premaxilla lateral to the external naris, first maxillary alveoli aligned with the last premaxillary
1088 alveoli, lateral margin of the maxilla that seem to have been parallel (the margins widen in *R.
1089 pachyrhynchus* even in much smaller specimens), even if the alveoli seem to slightly increase
1090 in size backward. Nevertheless, it also bears characters not found in *Ps. curvirostris* but in *R. pachyrhynchus* such as third and fourth premaxillary alveoli aligned with the sagittal axis, fifth
1091 premaxillary alveoli medial to the fourth, this latter being more lateral than the first maxillary
1092 alveolus, and a possible heterodonty (Table 1).
1093

1094 So, GSI (IM) E222 has an intermediate morphology between *Ps. curvirostris* and *R. pachyrhynchus*. It is clearly a different species, and maybe a different genus, than *Ps. curvirostris* and *R. pachyrhynchus*, but awaiting first hand observation and a clear revision of
1095 the specimen, we provisionally refer it to as cf. *Rhamphosuchus* n. sp.. It must be noted that
1096 Srivastava & Schleich (2018) associated the skull GSI (IM) E22 and mandible GSI (IM) E224 as
1097 the holotype of *Gavialis curvirostris gajensis*, but this is a mistake. GSI (IM) E224 is a mandible
1098 and is also a syntype of *G. breviceps* (see above).
1099
1100

1101 Additional maxillary and mandibular material were described from Tatrot Formation
1102 in Nepal, and attributed to *R. crassidens* (Corvinus & Schleich 1994; Srivastava & Schleich
1103 2018). This material is much younger (middle Pliocene) than the one described herein. The
1104 maxillary fragment (WIF/A 464) is poorly identifiable but the distance between the alveoli
1105 suggests that it could be referred to cf. *Rhamphosuchus* sp.. The second fragment has been
1106 originally described as an anterior part of premaxillary (NHM/TU 1989/27; Corvinus & Schleich
1107 1994; Srivastava & Schleich 2018), but absence of any trace of an external naris clearly states
1108 that it is an anterior extremity of a dentary symphysis. The alveoli are closely spaced, and the
1109 specimens can be attributed to cf. *Rhamphosuchus* sp..

1110 Ontogeny

1111 A strong difference in the growth of the anterior portion of the snout is noted when the length
1112 of three alveoli (L3) is compared with the width of the maxilla (W4), between extant *G. gangeticus* and *T. schlegelii*, and *G. curvirostris*, *R. pachyrhynchus*, and *G. leptodus* (Cautley,
1114 1868)(Fig. 16). None of the species shows an isometric growth between the growth of the
1115 length of three firsts maxillary alveoli and the snout width. The growth is less allometric in *T. schlegelii* (slope: 0.83) and *G. gangeticus* (slope: 0.65), and slightly more in *G. curvirostris* (slope: 0.54) (Fig. 16B). The width of the snout increases more rapidly than the length of the
1116
1117 first three alveoli in *R. pachyrhynchus* (slope: 0.16). In this species the length between three
1118 alveoli increases much less rapidly than the diameter of the alveoli, explaining that the alveoli
1119 are separated in small specimens, but packed in the largest. In the contrary, even if the
1120 distance between the alveoli decreases in most slender snouted species (*G. gangeticus*, *T. schlegelii*, *Ps. curvirostris*), the alveoli diameter less increases, and they remain distant from
1121 each other'. The values are comparable in both specimens referred to cf. *Rhamphosuchus* n.
1122
1123 sp., but with higher L3 values. This confirms that both specimens could pertain to a different
1124 species of *Rhamphosuchus*. The specimen referred to as "Garialis" sp. (GSI (IM) E222) has an
1125 intermediate position between *Ps. curvirostris* and *R. pachyrhynchus* in the graphs (Fig. 16).
1126
1127 Fig. 16

1128 The diameter of the alveoli does not strongly increase in *G. curvirostris*, in which the
1129 diameter varies from 6.7 to 12 mm (slope: 0.09), but more strongly increases with the snout
1130 width (and so the size of the animal) in *R. pachyrhynchus*, varying from 8.9 to 30 mm (slope:
1131 0.29). In the latter species, the growth proportions are similar to that observed in *T. schlegelii*
1132 for which the slop is also of 0.3, but with much smaller alveolus diameters and snout widths
1133 (Fig. 17).
1134 Fig. 17

1135 The data obtained for *G. leptodus* strongly differ from those obtained for *G.
1136 gangeticus*, the snout width being much larger compared to the length of three alveoli (Fig.
1137 16), suggesting that both species differ and that *G. leptodus* could be a valid species contrary
1138 to Martin *et al.* (2019). Also, the size of the alveoli is close to that observed in *G. curvirostris*
1139 and *G. gangeticus*, being from 9 to 13.5 mm, but with much wider mandible, from 87 to 120
1140 mm while the maximal width is of 50 mm in *G. curvirostris* and *G. gangeticus* (Fig. 17).

1141 The values obtained with the specimens from Pakistan attributed to *G. gangeticus*
1142 (Lydekker 1886) are also different from the values obtained with the extent specimens, the
1143 data being closer to those of *T. schlegelii* (Fig. 16).

1144

1145 Phylogenetic analysis

1146 The first analysis, including all taxa and equally weighted characters (EW-1), generated
1147 190 most parsimonious trees (Fig. 18; Courville *et al.* 2024, Appendix S4). It finds the classic
1148 morphologic relationships, *Portugalosuchus azenhae* being closely related to *Thoracosaurus*
1149 spp. and *Eothoracosaurus mississippiensis* to form the ‘thoracosaurses’, morphologic
1150 gavialoids are basal crocodylians and morphologic tomistomines deeper in the tree, within
1151 Crocodyloidea. The three newly included species of *Rhamphosuchus* (*R. crassidens*, *R.*
1152 *pachynrhynchus*, and cf. *Rhamphosuchus* n. sp.) are alternatively found as gavialoids or
1153 tomistomines.

1154 Fig. 18

1155 The second analysis, excluding *Po. Azenhae* (EW-2), generated 91 most parsimonious
trees in which gavialoids including morphologic tomistomines are sister taxon to crocodyloids,
1156 consistent with molecular results (Fig. 19; Courville *et al.* 2024, Appendix S4). As in most of
1157 previous results, *Maroccosuchus zennaroi* Jonet & Wouters, 1977 is the basalmost species of
1158 the clade, followed by *Kentisuchus*, forming a clade with *Megadontosuchus arduini* (de Zigno,
1159 1880). This suggests that this species could be reassigned to *Kentisuchus*, but the poor
1160 preservation of the single known specimen also suggests strong caution with the result. The
1161
1162 Gavialidae, grouping morphologic tomistomines and derived gavialoids, are highly unresolved (Fig. 19). Similar results are obtained when *Eothoracosaurus mississippiensis*, *Eosuchus* spp., and 'thoracosaurs' are alternatively excluded (EW-5 to 7; Courville *et al.* 2024, **Appendix S4**). Fig. 19

1166 When the matrix is reanalysed excluding *Rhamphosuchus crassidens*, *R. pachyrhynchus*, and cf. *Rhamphosuchus* n. sp. from Pakistan (but including *Po. azenhae*) (EW-3), the strict consensus of the 125 most parsimonious trees is consistent with morphological results and identical to the result obtained in the first analysis including all taxa (Fig. 18; Table 3).

1171 When *Rhamphosuchus* taxa (*Rhamphosuchus crassidens*, *R. pachyrhynchus*, cf. *Rhamphosuchus* n. sp.) and the 'thoracosaur' *Po. Azenhae* are excluded, the consensus tree of the 92 MPTs is congruent with molecular analyses (EW-4, Fig. 20). It is highly similar to that one obtained in Analysis EW-1 (Courville *et al.* 2024, Appendix S4), but the relationships of the morphological gavialoids included in tomistomines are better resolved. The morphological gavialoids are closely related to the Asian clade *Hanyusuchus sinensis* Iijima *et al.*, 2022 and *Toyotamaphimeia machikanensis*, *Penghusuchus pani* being closely related to this large clade. The relationships within morphological gavialoids are identical to those found in Analysis EW-1 (Fig. 18).

1180 The trees are particularly weakly supported with low Bremer indices and Bootstraps values (Figs. 18–20). This explains the high variation in the location of the morphological gavialoids from the base of the crocodylian tree to derived longirostres.
1183 Fig. 20

1184 All the analyses conducted with weighting methods (Implied and Extended Implied weighting) provide a result congruent with morphological analyses, Gavialoidea is the
basalmost crocodylian, including 'thoracosaurs', and Tomistominae is a Crocodylidae, not a gavialoid (Courville *et al.* 2024, Appendix S4). The results provide consensus trees better resolved than EW analyses, and they are homogeneous regardless the taxon included, with only very minor differences. Compared with EW-1 analyses obtaining classical morphological result, the differences are mainly located in the relationships of *Po. Azenhae* and *Rhamphosuchus* spp., the first being the relationships between tomistomines are also better resolved.

As previously noted, the presence of Upper Cretaceous to late Eocene species implies numerous ghost lineages, and strong incongruence with the Oligocene - Miocene age for the split between *Tomistoma* and *Gavialis* suggested by most molecular works, as in the results found in several analyses (Table 3). 'Thoracosaurs' are often considered as convergent with gavialoids, and several authors suggested that they should be considered as basal crocodylians, contrary to most derived species considered as closely related to *Tomistoma* (Gatesy *et al.* 2003; Harshman *et al.* 2003; Lee & Yates 2018; Darlim *et al.* 2022). Salas-Gismondi *et al.* (2016, 2022) suggested a possible monophyly of South American gavialoids as Gryposuchinae (also found herein in all analyses), a clade also including oldest African and Caribbean taxa (*Argochampsa krebsi* Hua & Jouve, 2004; *Aktiogavialis* spp.) when the morphological gavialoids are not constrained to be closely related to tomistomines (Salas-Gismondi *et al.* 2018). Could these species be more closely related to basal 'thoracosaurs' contrary to derived *Gavialis*? The Eocene African *Eogavialis africanus* (Andrews, 1901) is basal to the clade *Gavialis* + Gryposuchinae in the same analysis. Could it be also more closely related to gryposuchins than to Asian species? Its Eocene age, and its relationships more closely related to *Gavialis* than to *Tomistoma* is not congruent with the Late Oligocene - Early
1210 Miocene age proposed in the most recent molecular analyses for the divergence estimate for
1211 *Gavialis* — *Tomistoma*. Of course, this is highly speculative and needs to be much more deeply
1212 investigated, a direction far from the scopes of the present paper, but such hypotheses should
deserve to be explored in the future.
1213

1214 Our phylogenetic results, as most of the crocodilian phylogenetic analyses, seem to
1215 suffer from two different problems. When *Gavialis*—'thoracosaurs' clade is found as basal
1216 crocodylian as in classical morphological analyses, the distant relationships between *Gavialis*
1217 and *Tomistoma* is incongruent with molecular results. When *Gavialis* and 'thoracosaurs' are
1218 found as closely related to *Tomistoma*, the result is more congruent with molecular results,
1219 but strongly stratigraphically incongruent with divergence ages provided by the same
1220 molecular analyses. This suggests that the *Gavialis*—'thoracosaurs' relationships are based
1221 on homoplasies, a hypothesis confirmed by the strong influence of inclusion or exclusion of
1222 'thoracosaurs' in the obtention of molecular or morphologic results. As IW and EIW weight
1223 homoplasy, these methods seem to consider some of the characters found as homologous
1224 to *Gavialis*+*Tomistoma*+'thoracosaurs' in some analyses (molecular results) as homoplastic
1225 in our analyses. They also failed to identify the homoplastic characters supporting *Gavialis*—
1226 thoracosaurs' clade, and to solve the *Gavialis*—*Tomistoma* problem. This should be more
1227 deeply investigating, and analysis of the characters weighted proposed by EIW and IW, and
1228 of differences in the characters supporting the classical molecular and morphological
1229 analyses, and those supporting the *Gavialis*—'thoracosaurs' would be of particular interest,
1230 but this is far beyond the scope of the present paper. **Bugti crocodylians**

1231 In the first analysis (*Po. azenhae* is included; Fig. 18), the phylogenetic analysis finds
1232 alternatively cf. *Rhamphosuchus* n. sp. as the sister taxon to *Rhamphosuchus pachyrhynchus*
1233 and *Rhamphosuchus crassidens* within morphological gavialoids (Fig. 18A), or closely within
morphological tomistomines, related to European *Gavialosuchus eggenburgensis* Toula & Kail, 1885 and *T' lusitanica*, the two *Rhamphosuchus* species being closely related to the Asian clade *H. sinensis*, *P. pani* and *T. machikanensis* (Fig. 18B). In their first relationships, the three *Rhamphosuchus* species are closely related to the clade including *Eogavialis africanum*, South American gavialoids, and the clade formed by *Ps. curvirostris* and *Gavialis*. The clade is supported by two synapomorphies: all the dentary teeth occlude lingual to the maxillary teeth (92) and there is a depression on the ventral surface of the premaxilla between the first and second alveoli (not for tooth occlusion) (257). The last character state is also observed in *Ps. curvirostris*, *Gavialis* spp. and *T. schlegelii*. The clade including *R. crassidens* and *R. pachyrhynchus* is supported by two synapomorphies: the anterior lateral margin of the maxilla is convex, with an anterior undulation (94), and the maxillary alveoli are closely spaced, the seventh and eighth being not more spaced than the others (201).

In their second relationships, *R. pachyrhynchus* and *R. crassidens* are sister taxa, supported by one synapomorphies (Fig. 18B) (all the dentary teeth occlude lingual to the maxillary teeth (92)). They are closely related to the clade including *Penghusuchus pani*, *Toyotamaphimeia machikanense*, and *Hanyusuchus sinensis*, supported by three synapomorphies present in both species of *Rhamphosuchus* (the maxillary alveoli vary in size (200), the maxillary alveoli are closely spaced, the seventh and eighth being not more spaced than the others (201), the mandibular symphysis extends posteriorly between the level of the 13th and 18th alveoli (238)).

Inclusion or deletion of *Po. azenhae* from the analyses has strong consequences on the relationships of species of *Rhamphosuchus* found alternatively as gavialoids, or as tomistomines depending on the congruence of the result considered with traditional molecular or morphological analyses (Figs 18–19). The relationships obtained when the
1258 'thoracosaur' *Po. azenhae* is excluded, *Rhamphosuchus* spp. more closely related to Neogene
1259 Asian tomistomines (Fig. 19), seems to be more pertinent than their close relationships with
1260 the African Late Eocene *E. africanum* and South American gavialoids obtained when *Po.*
1261 *azenhae* is included (Fig. 18A).

1262 Using implied and extended implied weighting methods, *Rhamphosuchus* spp. is found
1263 as paraphyletic at the base of the gavialoids, being more closely related to other gavialoids
1264 than *Po. Azenhae* (Fig. 21; Courville *et al.* 2024, Appendix S4). This is particularly incongruent
1265 with the stratigraphic distribution as the Oligo-Miocene *Rhamphosuchus* spp. is less derived
1266 within gavialoids than the Maastrichtian *E. mississippiensis*.

1267 In all analyses *Ps. curvirostris* is closely related to *Gavialis* (Figs 18–21). This clade is
1268 supported by two characters: the interorbital distance is wider than the narrowest width of
1269 the snout (210), and there is a depression on the ventral surface of the premaxilla between
1270 the first and second alveoli (not for tooth occlusion) (257). This close relationships could justify
1271 that the species from Pakistan could have been included in the genus *Gavialis*, but we
1272 considered that the species currently included in *Gavialis*, such as *G. bengawanicus* and *G.
1273 browni*, are homogeneous with orbits strongly telescoped, a particular shape of their
1274 premaxillae, the absence of contact between the premaxillae and the nasal, characters absent
1275 in *Ps. curvirostris*. So, this species strongly differs from all *Gavialis* species, justifying the
1276 erection of a new genus.

1277
1278

1279 **CONCLUSION**

1280
1281 The description of this new material from the Bugti Hills sheds new light on the crocodylian diversity in the Indo-Pakistan area during the Early Miocene, a key period for the diversification and split between tomistomines and gavialids. They represent two lineages in the same stratigraphic level and same area. The first is closely related to the Siwalik Hills *Rhamphosuchus crassidens*, and pertain to the same genus, while the second represents a new genus, closely related to the extent *Gavialis gangeticus*.

1287 Using a revised version of a previous phylogenetic matrix, the result found gavialoids alternatively as basal crocodylians, as in traditional morphological analyses, or as sister taxon to crocodyloids, more closely related to tomistomines, as in gene-based analyses. So, the species introduced in the matrix has strong consequences on the relationships of crocodylians.
1288
1289
1290
1291 Our result including all species is consistent with classical morphological analyses. The deletion of all 'thoracosaurs' or of some of them has strong influence on the results and finds the molecular phylogenetic structure. This confirms that most of the *Gavialis - Tomistoma* issue is related to the relationships of the 'thoracosaurs'. A better knowledge of these taxa is one of the keys to solve the problem. Nevertheless, when the molecular result is found, a large number of morphological gavialoids makes the result strongly stratigraphically incongruent, not only species usually recognized as 'thoracosaurs'. So, to simply find the molecular result with morphological data does not solve the *Gavialis - Tomistoma* problem but sets different ones. Which of the species considered as morphological gavialoids are really gavialids? Are the South American forms and pre-Oligocene species gavialoids or are they more closely related to usual 'thoracosaur's? This should be a direction for future research.
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302

1303 *Acknowledgements.* We are very grateful to the late Nawab Akbar Shahbaz Khan Bugti, Lord of the Bugti Tribes, for his constant support and interest in our work; Zulficar, Brahumdagh
Khan Bugti, and Shaheed Hassan Bugti for their invitations and help. We thank Nayyer Iqbal and Ghazala Roohi (Pakistan Museum of Natural History, Islamabad) for their efficient support.

We are thankful to Kamal Madjidulah (Karachi) for his tireless assistance and enthusiasm.

Many thanks to Marc de Grossouvre (French Embassy, Islamabad) for his great interest in our French/Pakistani collaborative program. The Ministry of Foreign Affairs (MAE) via the French Embassy in Islamabad, the CNRS (Eclipse-Program), MNHN, Université de Montpellier, the Fondation de France, the Leakey, Fyssen, Bleustein-Blanchet, and Singer-Polignac Foundations, and the Carnegie Museum of Natural History (Pittsburgh) have financially supported this project. This is MPFB article No. 36. We warmly thank Philippe Loubry and Lilian Caze for the photographs included in the paper, Vincent Pernègre for the access to the MNHN collections, and Yves Laurent for access to the MHNT collections. I thank L. Steel from the Natural History Museum of London for her help, hospitality, and access to collections.

SJ received support from the SYNTHESYS Project (http://www.synthesys.info/), which is financed by the European Community Research Infrastructure Action under the FP7 'Capacities' Program (GB-TAF-3366). This paper is dedicated to the memory of Jean-Loup Welcome, who passed away on May 18th, 2021. A long-time colleague and friend, Jean-Loup initiated the field project in the famous Bugti Hills thanks to his personal ties with Nawab Bugti, and led the project until its end in 2004. None of this would have been possible without his courage, perseverance, humanity, and friendship. Comments from J. Ristevski, an anonymous reviewer, and P. Mannion (Editor), improved an early version of this manuscript.

Author contributions. **Conceptualization** E Courville (EC), S Jouve (SJ), G Métais (GM); **Data curation** EC, SJ; **Formal Analysis** EC, SJ; **Funding Acquisition** GM, LM, POA; **Investigation** EC, SJ, GM; **Project Administration** GM; **Supervision** SJ, GM; **Validation** SJ, GM; **Writing – Original Draft Preparation** EC, SJ, GM; **Writing – Review & Editing** POA, LM.
1330

1331 DATA ARCHIVING STATEMENT

1332 This published work and the nomenclatural acts it contains, have been registered in ZooBank:

1333 http://zoobank.org:act:1968216C-0EFA-4E60-BE6D-98487E69606F

1334 Data for this study, including data used in the phylogenetic analysis (character list and matrix),

1335 tables of material used, and measurements are available in the Dryad digital repository:

1336 doi:10.5061/dryad.1g1jwsv6b.

1337 Reviewer

1338 URL: http://datadryad.org/stash/share/vRhcu9kb7IRa2V71CDZZAjqO82bwnznjfmP8AmLv-

1339 wg

1340

1341 SUPPORTING INFORMATION

1342 **Appendix S1.** Size estimation in *Rhamphosuchus pachyrhynchus

1343

1344 **Appendix S2.** List of characters used in the phylogenetic analyses.

1345

1346 **Appendix S3.** Data matrix used in the phylogenetic analyses.

1347

1348 **Appendix S4.** Complete consensus trees obtained with the phylogenetic analyses including and

1349 excluding various taxa.

1350

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1652 Vélez, K. I. 2024. *New Paleontological Records Provide Insights Into the Early Evolution
and Biogeography of Gavialoids*. University of Michigan, 172 pp.

1654
1655 Vickary, N. 1846. Geological Report on a portion of the Beloochistan Hills. *Quarterly Journal
of the Geological Society*, 2, 260-267, doi: 10.1144/GSL.JGS.1846.002.01-02.44.
1657 Walter, J., Darlim, G., Massonne, T., Aase, A., Frey, E. & Rabi, M. 2022. On the origin of
1658 Caimaninae: insights from new fossils of *Tsoabichi greenriverensis* and a review of
1659 the evidence. *Historical Biology*, 1–16, doi: [10.1080/08912963.2021.1938563](https://doi.org/10.1080/08912963.2021.1938563).

1660 Welcomme, J.-L. & Ginsburg, L. 1997. Mise en évidence de l'Oligocène sur le territoire des
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1662 1004.

1663 Welcomme, J.-L., Benammi, M., Crochet, J.-Y., Marivaux, L., Métais, G., Antoine, P.-O. &
1664 Baloch, I. 2001. Himalayan Forelands: palaeontological evidence for Oligocene detrital
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1667 Wu, X.-C., Li, C. & Wang, Y. 2018. Taxonomic reassessment and phylogenetic test of
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1669 *Vertebrata PalAsiatica*, 56, 137–146.

1670 Yeh, H.-K. 1958. A new crocodile from Maoming, Kwangtung. *Vertebrata PalAsiatica*, 2,
1671 237–242.

1672 Young, M. T., Hastings, A. K., Allain, R. & Smith, T. J. 2016. Revision of the enigmatic
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1673
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1678 *Memorie della classe di Scienze fisiche, matematiche e naturali*, **3**, 1–10.

1679
1680

1681

1682
1683 **CAPTIONS**

1684 **FIG. 1.** Location of the Bugti Hills (A, black rectangle), Kumbi locality (B) and stratigraphic log of the site (C). Numbers in Figure A indicate several localities where longirostrine crocodylian material (holotype) has been discovered: 1, Dhok Pathan, Pakistan, where the remains of *G. lewisi* originated; 2, Potwar Plateau, Pakistan, where the remains attributed to *R. crassidens* were discovered; 3, Sehwan in Sindh (Pakistan) and the Gaj series where *G. pachyrhynchus* and *G. curvirostris* were discovered; 4, Siwalik Hills, India, where *G. gangeticus*, *G. hysudricus*, and *G. leptodus* were discovered; 5, Gandoï (Modified from Métais *et al.* 2009).

1691 Full page

1692

1693 **FIG. 2.** *Rhamphosuchus pachyrhynchus*, GSI (IM) E30, Holotype, Laki Hills, Sind, Pakistan; anterior portion of a snout. **A**, dorsal. **B**, ventral. **C**, left lateral views. From Lydekker (1886).
1694 Scale bar: 5 cm.

1696 Single column

1697

1698 **FIG. 3.** *Rhamphosuchus pachyrhynchus*, level 4, Aquitanian, Gaj of Kumbi, Bugti Hills. **A–C**, GSI (IM) E226, syntype of "Garialis" breviceps, anterior portion snout: **A**, dorsal view; **B**, ventral view; **C**, and lateral view. **D**, GSI (IM) E224, syntype of "Garialis" breviceps, mandibular portion in dorsal view. From Pilgrim (1912). Scale bar: 5 cm.

1702 2/3 page

1703

1704 **FIG. 4.** Snout remains of *Rhamphosuchus pachyrhynchus*, level 4, Aquitanian, Kumbi, Bugti Hills. **A–B**, MNHN.PAK 1914, anterior portion of a snout: **A**, in dorsal view; **B**, interpretative drawing of A. **C–D**, MNHN.PAK 1914: **C**, in ventral view; **D**, interpretative drawing of C. **E**,
1707 MNHN.PAK 1914 in lateral view. F, MNHN.PAK 1959, anterior extremity of premaxillae in
1708 ventral view. G–H, MNHN.PAK 1915, left premaxilla: G, in ventral view; H, lateral view. I–J,
1709 MNHN.PAK 530, mid portion of a snout: I, in dorsal view; J, interpretative drawing of I. K–N,
1710 MNHN.PAK 530: K, in dorsal view; L, interpretative drawing of K; M, detail of K; N,
1711 interpretative drawing of M. Scale bar, 5 cm. Abbreviations: Cr, crest; Dp, depression; EN,
1712 external naris; Fo, foramen; Mx, maxilla; N, nasal; OP, occlusal pit; Pmx, premaxilla. Scale bar:
1713 5 cm.

1714 Full page

1715

1716 **FIG. 5.** Skull remains of *Rhamphosuchus pachyrhynchus*, level 4, Aquitanian, Kumbi, Bugti Hills.
1717 A–C, MNHN.PAK 547, part of a right premaxilla: A, in dorsal view; B, ventral view; C, lateral
1718 view. D, MNHN.PAK 900, portion of maxilla in ventral view. E, MNHN.PAK 534, posterior
1719 portion of a left maxilla in ventral view. F–G, MNHN.PAK 456, anterior portion of maxillae: F,
1720 in dorsal view; G, interpretative drawing of F. H–I, MNHN.PAK 456, anterior portion of
1721 maxillae: H, in ventral view; I, interpretative drawing of H. J–K, MNHN.PAK 539, portion of a
1722 left maxilla: J, in lateral view; K, ventral view. L–M, MNHN.PAK 535, mid portion of a right
1723 maxilla: L, in lateral view; M, ventral view. N–P, MNHN.PAK 595, portion of a left jugal: N, in
1724 lateral view; O, ventral view; P, interpretative drawing of O. Q, MNHN.PAK 542, posterior
1725 portion of a right maxilla in ventral view. R–T, MNHN.PAK 596, posterior portion of a right
1726 jugal: R, in lateral view; S, ventral view; T, interpretative drawing of S. U, MNHN.PAK 531,
1727 posterior portion of a left maxilla in ventral view. Scale bar: 5 cm. Abbreviations: Cr, crest; Dp,
1728 depression; Ect, ectopterygoid; EN, external naris; Fo, foramen; J. jugal; Mx, maxilla; N, nasal;
1729 OP, occlusal pit; Pmx, premaxilla; SoF, suborbital fenestra.

1730 Full Page
1731
1732 **FIG. 6.** Comparison of the ventral surface of the premaxilla in various longirostrine
crocodylians. A, *Tomistoma schlegelii*. B, *Gavialis gangeticus*. C, *Gavialis cf. bengawanicus*
1733
1734 (from Martin *et al.* 2012). D, *Mecistops cataphractus*, MNHN.1930.192. Scale bar: 5 cm.
1735 Abbreviations: Dp, depression.

1736 Single column

1737
1738 **FIG. 7.** Mandibular remains of *Rhamphosuchus pachyrhynchus*, level 4, Aquitanian, Kumbi, Bugti Hills. A, MNHN.PAK 545, anterior portion of dentary symphysis in dorsal view. B–C, MNHN.PAK 1920, anterior portion of a left dentary symphysis: B, in dorsal view; C, ventral view. D, MNHN.PAK 540, posterior part of a right mandibular symphysis in dorsal view; E–G, MNHN.PAK 719, mid part of a right mandibular symphysis: E, in lateral view; F, dorsal view; G, ventral view. H–I, MNHN.PAK 553, mid part of a left mandibular ramus; H, in dorsal view; I, lateral view. Scale bar: 5 cm. Abbreviations: D, dentary; Sa, surangular; Spl, splenial; DA4, fourth dentary alveolus.

1746 2/3 page

1747
1748 **FIG. 8.** Mandibular remains of *Rhamphosuchus pachyrhynchus*, level 4, Aquitanian, Kumbi, Bugti Hills. A, MNHN.PAK 1290, mandible in dorsal view. B, left premaxillary fragment in lateral view. C, portion of snout in ventral view. Scale bar: 5 cm. Abbreviations: Alv, alveolus; D, dentary; LMEN, lateral margin of the external naris; Mx, maxilla; OP?, occlusal pit?; San, surangular; Spl, splenial.

1753 Single column

1754
1755 **FIG. 9.** GSI (IM) E29, anterior portion of maxillae referred as *Rhamphosuchus* cf.

1756 *pachyrhynchus*, lower Siwaliks of Schwan, Sind, Pakistan. Scale bar: 5 cm.

1757 Single column

1758

1759 **FIG. 10.** MNHN.PAK 919, anterior portion of dentary referred as *Rhamphosuchus* cf.

1760 *pachyrhynchus*, level 4, Aquitanian, Kumbi, Bugti Hills. A, lateral view; B, dorsal view. Scale

1761 bar: 5 cm.

1762 Single column

1763

1764 **FIG. 11.** Cf. *Rhamphosuchus* n. sp., GSI (IM) E222, holotype of *Garialis curvirostris* var. *gajensis*,

1765 Gaj of Kumbi, Bugti Hills. From Pilgrim, 1912. Scale bar: 5 cm.

1766 2/3 page

1767

1768 **FIG. 12.** *Pseudogavialis curvirostris*, GSI (IM) E26, holotype, lower Siwalik of the Laki Hills,

1769 Sindh; Skull. A, anterior portion of skull in dorsal view; B, mid portion of skull in dorsal view;

1770 C, anterior portion of snout in lateral view; D, ventral view; E, mid portion of skull in left lateral

1771 view; F; *Pseudogavialis curvirostris*, holotype of *Garialis curvirostris* var. *gajensis* GSI (IM) E223,

1772 Gaj of Kumbi, Bugti Hills, mandibular symphysis in dorsal view. Scale bar: 5 cm. A-E from

1773 Lydekker (1886); F from Pilgrim, 1912.

1774 2/3 page

1775

1776 **FIG. 13.** *Pseudogavialis curvirostris*, level 4, Aquitanian, Gaj of Kumbi, Bugti Hills. A-D,

1777 MNHN.PAK 459, posterior portion of maxillae and anterior portions of maxillae: A, in dorsal

1778 view; B, interpretative drawing of A; C, ventral view; D, interpretative drawing of C. E-F,
1779 MNHN.PAK 480: E, anterior part of a left premaxilla; F, interpretative drawing of E. G-I,
1780 MNHN.PAK 1956a, premaxillae: G, in dorsal view; H, in ventral view; I, interpretative drawing
1781 of H. J-M, MNHN.PAK 457+458, mid portion of a snout: J, in dorsal view; K, interpretative
1782 drawing of J; L, ventral view; M, interpretative drawing of L. N-R, MNHN.PAK 560, mid part of
1783 a snout: N, in dorsal view; O interpretative drawing of O; P, ventral view; Q, interpretative
drawing of P; R, lateral view. Scale bar: 5 cm. Abbreviations: Cr, crest; Dp, depression; EN,
1784 external naris; FI, foramen incisivum; L, lacrimal; Mx, maxilla; N, nasal; ODp, occlusal
depression; OP, occlusal pit; PI, palatine; PMD, premaxilla-maxilla depression; PMx,
1786 premaxilla; PMXp, posterior maxillary process; Alv4, fourth alveolus; Alv5, fifth alveolus; Alv6,
1787 sixth alveolus.
1788

1789 Full page

1790

1791 **FIG. 14.** *Pseudogavialis curvirostris*, reconstruction of the skull and mandible. A,
1792 reconstruction of the anterior part of the skull in dorsal; B, ventral view; C, reconstruction of
1793 the mandible in dorsal view.

1794 2/3 page

1795

1796 **FIG. 15.** *Pseudogavialis curvirostris*, level 4, Aquitanian, Kumbi, Bugti Hills. A, MNHN.PAK 833,
1797 anterior portion of a right dentary in dorsal view. B-D, MNHN.PAK 562+463, midportion of a
1798 mandibular symphysis: B, in lateral view; C, dorsal view; D, interpretative drawing of C. E-F,
1799 MNHN.PAK 444, posterior portion of a mandibular symphysis: E, in dorsal view; F,
1800 interpretative drawing of E. G-I, MNHN.PAK 903, posterior portion of a mandibular symphysis:
1801 G, in lateral view; H, dorsal view; I, interpretative drawing of H. J-K, MNHN.PAK 450, portion
1802 of a left mandibular symphysis: J, in dorsal; K, lateral view. L-N, MNHN.PAK 905, posterior part
1803 of a left mandibular ramus: L, in lateral view; M, dorsal view; N, interpretative drawing of M.

1804 O-P, MNHN.PAK 908, portion of a right dentary symphysis: O, in dorsal view; P, lateral view.

1805 Scale bar: 5 cm. Abbreviations: D, dentary; Spl, splenial.

1806 Full page

1807

1808 **FIG. 16.** Comparison of snout proportions from various gavialoid and tomistomine species. A,

1809 comparison between the width of the mandible or dentary symphysis and the ratio between

1810 the length of three alveoli and the snout/mandible width; B, Comparison between the width

1811 of the mandible or dentary symphysis and the length of three alveoli. (For data see Courville

1812 *et al.* 2024, Table 2).

1813 Full page

1814

1815 **FIG. 17.** Comparison of alveoli diameter with the snout width for various gavialoid and

1816 tomistomine species (For data see Courville *et al.* 2024, Table 3).

1817 2/3 page

1818

1819 **FIG. 18.** Result from the analyses EW-1 (all taxa included) and EW-3 (*Rhamphosuchus* spp.

1820 excluded) using equally weighted characters. For the analysis EW-1 (all taxa included) (Table

1821 1), consensus tree (2059 steps; CI, 0.194; RI, 0.440) from 190 most parsimonious trees with a

1822 length of 1354 steps (RI, 0.678; CI, 0.295). A and B are the alternative relationships of

1823 *Rhamphosuchus* spp. found in the most parsimonious trees (For complete tree see Fig. S1,

1824 Courville *et al.* 2024, Appendix S4). For the analysis EW-3 (*Rhamphosuchus* spp. excluded),

1825 consensus tree (1409 steps, CI, 0.283; RI, 0.659) from 125 most parsimonious trees with a
1826 length of 1333 steps (RI, 0.685; CI, 0.299). (For complete tree see Fig. S3, Courville *et al.* 2024,
1827 Appendix S4). Italicized number are Bremer indices.

1828 **Full page**

1829

1830 **FIG. 19.** Result from the analysis EW-2 using equally weighted characters, *Portugalosuchus azenhae* excluded from the analysis, consensus tree (1712 steps; CI, 0.233; RI, 0.557) from 91
1831 most parsimonious trees with a length of 1347 steps (RI, 0.680; CI, 0.296). (For complete tree
1832 see Fig. S2, Courville *et al.* 2024, Appendix S4). Italicized number are Bremer indices.

1834 2/3 page

1835

1836 **FIG. 20.** Result from the analysis EW-4 using equally weighted characters, *Po. azenhae*, *R. crassidens*, *R. pachyrhynchus*, and cf. *Rhamphosuchus* n. sp. are excluded, consensus tree (1385 steps; CI, 0.288; RI, 0.668) from 92 most parsimonious trees with a length of 1326 steps
1837 (RI, 0.687; CI, 0.301). (For complete tree see Fig. S4, Courville *et al.* 2024, Appendix S4).
1838
1839
1840 Italicized number are Bremer indices.

1841 Full page

1842

1843 **FIG. 21.** Result from the analyses EIW3-1 and EIW12-1, using extended implied weighting with different K values. **A**, result from the analyses EIW3-1 (all taxa included) with K=3, consensus
1844 tree (1381 steps, CI, 0.299; RI, 0.665) (For complete tree see Fig. S22, Courville *et al.* 2024,
1845 Appendix S4); **B**, alternative relationships of some taxa obtained in the analyses EIW12-1 (all
1846 taxa included) with K=12 (Table 1), consensus tree (1367 steps, CI, 0.302; RI, 0.669) (For
1847 complete tree see Fig. S29, Courville *et al.* 2024, Appendix S4).
1848

1849 Full page
1850

**TABLE. 1.** Description of the main morphological characters used in the description of the new
fossil species described in this paper.

1853

**TABLE. 2.** Taxonomic revision of crocodylian taxa discussed in this work.

1854

**TABLE. 3.** Phylogenetic analyses conducted, data used, taxa excluded, and figures associated.
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P. curvirostris (Holotype, IM E26)

Pseudogavialis curvirostris

Rhamphosuchus pachyrhynchus

R. pachyrhynchus (Holotype, IM E30)

R. aff. pachyrhynchus (IM E29)

R. aff. pachyrhynchus (MNHN.PAK919)

cf. Rhamphosuchus sp. (IM E222)

Gavialis leptodus

Gavialis gangeticus

Tomistoma schlegelii

R. pachyrhynchus

$$y = 0,287x - 3,4957$$

$$R^2 = 0,8854$$

T. schlegelii
$$y = 0,2989x + 0,9796$$

$$R^2 = 0,8797$$

P. curvirostris
$$y = 0,0895x + 6,5421$$

$$R^2 = 0,3236$$

G. gangeticus
$$y = 0,1975x + 2,0068$$

$$R^2 = 0,8185$$

G. leptodus
$$y = 0,0968x + 0,7062$$

$$R^2 = 0,1811$$
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