# A new genus of lonchidiid hybodontiform sharks from the Cretaceous of North Africa and South America

Romain Vullo, Léo Galvão Carnier Fragoso, Jonathas S Bittencourt, Adán Pérez-García, Imad Bouchemla, Madani Benyoucef

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Romain Vullo, Léo Galvão Carnier Fragoso, Jonathas S Bittencourt, Adán Pérez-García, Imad Bouchemla, et al.. A new genus of lonchidiid hybodontiform sharks from the Cretaceous of North Africa and South America. Geological Magazine, 2026, 163, pp.e6. 10.1017/S0016756825100484. insu-05476138

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# A new genus of lonchidiid hybodontiform sharks from the Cretaceous of North Africa and South America

Romain Vullo<fnref n="1" /> ID, Léo Galvão Carnier Fragoso², Jonathas S. Bittencourt², Adán Pérez-García³, Imad Bouchemla⁴,⁵ ID and Madani Benyoucef⁵

## Rapid Communication

**Cite this article:** Vullo R, Fragoso LGC, Bittencourt JS, Pérez-García A, Bouchemla I, and Benyoucef M. A new genus of lonchidiid hybodontiform sharks from the Cretaceous of North Africa and South America. *Geological Magazine* **163**(e6): 1–9. https://doi.org/10.1017/S0016756825100484

Received: 15 September 2025

Revised: 3 December 2025

Accepted: 8 December 2025

**Keywords:**

Elasmobranchii; Euselachii; hybodontiformes; teeth; heterodont dentition; Mesozoic; Gondwana

**Corresponding author:**

Romain Vullo;

Email: romain.vullo@univ-rennes.fr

## Abstract

Minute hybodont shark teeth from uppermost Albian–lower Cenomanian (mid-Cretaceous) continental deposits of Djebel Amour (Saharan Atlas, Algeria) are described. They are assigned to a new genus and species of Lonchidiidae, *Lonchidionoides trifurcatum*. Similar teeth recently reported from the Early Cretaceous of Brazil are here referred to as *Lonchidionoides* sp. The heterodont dentition of *Lonchidionoides* is characterized by clutching anterior teeth with a tricuspid crown and larger crushing posterior teeth with less individualized cusps. Lateral teeth show an intermediate morphology. The two occurrences of this non-marine hybodontiform genus may reflect the existence of a large ancestral distribution area that was divided during the opening of the South Atlantic, as previously suggested for several groups of cartilaginous and bony fishes.

## 1. Introduction

Hybodontiformes are an extinct group of euselachian sharks that ranged from the Late Devonian to the Late Cretaceous (Coates & Gess, 2007). Based on their rich fossil record, the highest genus-level diversity was reached during the Early Cretaceous, a time interval marked by the differentiation of three palaeobiographic provinces (Asia, Europe–North America and Africa–South America) and the appearance of numerous non-marine forms (Cuny et al. 2008; Cuny, 2012). In West Gondwana, the Early to mid-Cretaceous hybodont shark communities of the African–South American province were dominated by distobatids (*Distobatus*, *Tribodus*, *Aegyptobatus*) but also comprised taxa such as the hybodontid *Priohybodus*, the possible lonchidiids *Bahariyodon* and *Diabodus* and the enigmatic genus *Pororhiza* (Brito & Ferreira, 1989; Werner, 1989; Duffin, 2001; Cuny et al. 2004, 2008; Cuny, 2012; Brito et al. 2025; Neves et al. 2025). All these genera were endemic to this province except *Tribodus*, which also inhabited the western part of the European archipelago (Vullo & Néraudeau, 2008; Cuny, 2012). Here we report the discovery of a new genus and species of Lonchidiidae based on isolated teeth from uppermost Albian–lower Cenomanian fluvial deposits of Algeria, and we assign to this genus some isolated teeth from Barremian– Aptian lacustrine deposits of Brazil previously described as ?Lonchidiidae (Fragoso et al. 2021).

The studied Algerian specimens are housed in the palaeontological collections of the Geomatics, Ecology and Environment Laboratory (LGEE) at the Mustapha Stambouli University of Mascara, Algeria, under the collection acronym LGEE-GH-SA. The studied Brazilian specimens are housed at the Instituto de Geociências of the Universidade Federal de Minas Gerais (UFGM) in Belo Horizonte, Brazil, under the collection acronym (IGC-P). The ZooBank LSID (Life Science Identifier) for this publication is: urn:lsid:zoobank.org:pub: D8890DB3-0D1F-48F1-84AA-710BE089FBE9.

## 2. Geological settings

### 2.a. 'Garet El Hemmam' locality, Algeria

The Algerian material described in this study was collected from the upper, vertebrate-bearing section of the Tiout Formation in the Djebel Amour (central Saharan Atlas) (Bassoullet & Iliou, 1967; Bassoullet, 1973), exposed at the 'Garet El Hemmam' locality (34° 0' 51.39" N; 2° 57' 20.33" E) in the northeastern part of the Laghouat Province (Figure 1a, c). This stratigraphic

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CAMBRIDGE
UNIVERSITY PRESS

<footnote n="1">¹Univ Rennes, CNRS, Géosciences Rennes, UMR 6118, Rennes, France; ²Laboratório de Paleontologia e Macroeevolução, CPMTC-IGC, Departamento de Geologia, Instituto de Geociências, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil; ³Grupo de Biología Evolutiva, Facultad de Ciencias, Universidad Nacional de Educación a Distancia, Las Rozas, Spain; ⁴Department of Geological Sciences, Faculty of Biological and Agricultural Sciences, Mouloud Mammeri University of Tizi-Ouzou, Tizi-Ouzou, Algeria and ⁵Laboratoire de Géomatique, Ecologie et Environnement, Mustapha Stambouli University of Mascara, Mascara, Algeria</footnote>

<footnote>© The Author(s), 2026. Published by Cambridge University Press. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.</footnote>
<figure><img src="image_3.png" /><figcaption>**Figure 1.** Maps of the Laghouat Province (N Algeria) (a) and Minas Gerais State (SE Brazil) (b) showing the location of the 'Garet El Hemmam' and 'Fazenda Tereza' sites, respectively, and stratigraphic sections (c, d) showing the position of the fossil-bearing beds that have yielded the teeth of *Lonchidionoides* gen. nov.</figcaption></figure>

interval has been assigned to the uppermost Albian–lower Cenomanian based on regional biostratigraphic correlations (Benyoucef et al. 2017). The specimens originate from two closely spaced layers (samples Gh9 and Gh11), which are positioned about 100 m below the base of the El Rhelida Formation.

The upper part of the Tiout Formation comprises fine- to medium-grained, moderately to well-sorted sandstones (ranging from 0.20 to 50 m thick), interbedded with clay layers (0.10 to 4 m thick) and channelized, matrix-supported microconglomerates (0.10 to 0.60 m thick). Some of the sandstone beds preserve hydrodynamic sedimentary structures and invertebrate burrows and tetrapod swim tracks (Bouchemla et al. 2023). The clay intervals are predominantly red or greenish, display parallel lamination and occasionally yield fossil wood fragments, sparse smooth-shelled, low-diversity ostracod assemblages and rare fish remains (sample Gh9 comes from one of these beds). The microconglomerates are composed of sub-rounded quartz pebbles (0.1–2 cm in diameter) set in a fine- to medium-grained, poorly sorted matrix (sample Gh11 comes from one of these beds). These microconglomerates represent the primary fossiliferous units, yielding abundant vertebrate remains, including elasmobranchs (e.g. *Onchopristis numida*), actinopterygians (e.g. *Bawitius* sp.),

actinistians (Mawsoniidae indet.), dipnoans (*Neoceratodus africana-nus*), testudines, crocodyliforms, non-avian dinosaurs (including the theropods *Spinosaurus aegyptiacus* and *Carcharodontosaurus saharicus*), indeterminate bones and teeth and coprolites; invertebrate remains consist of ostracods (Benyoucef et al. in prep.). In sample Gh11, fish microremains co-occurring with the new lonchidiid belong to *Tribodus* sp., Sclerorhynchoidei indet., *Onchopristis numida*, Pycnodontidae indet., Ginglymodi indet. and Amiidae indet.

The upper Tiout Formation correlates with the uppermost part of a widespread continental siliciclastic sequence across northern Africa, historically referred to as the 'Continental Intercalaire' (Kilian, 1931). In Algeria, the upper Tiout Formation is considered equivalent to the 'Grès rouges' Formation at the base of the Cretaceous succession in the Guir Basin (Bechar Province), near the Algerian–Moroccan border (Benyoucef et al. 2015), the Gara Samani Formation in the Tademait Plateau (Benyoucef et al. 2022) and the Djoua series along the Algerian–Libyan border (Lefranc, 1983). Outside Algeria, it correlates with famous vertebrate-bearing deposits of North Africa such as the Kem Kem beds in eastern Morocco and the Bahariya Formation in western Egypt (Le Loeuff et al. 2012).
## 2.b. 'Fazenda Tereza' locality, Brazil

The fossils from Brazil were collected at 'Fazenda Tereza', a traditional fossil locality (17° 37' 32.38" S; 45° 54' 22.48" W) in the Sanfranciscana Basin, located in João Pinheiro, in the northwestern part of the Minas Gerais State (Bittencourt *et al.* 2015, 2022) (Figure 1b, d). The local sedimentary succession comprises packages of claystone and siltstone with planar-parallel bedding (when present) and fine- to medium-grained sandstones. This succession is typical of the lacustrine strata of the Quiricó Formation (Campos & Dardenne, 1997; Sgarbi *et al.* 2001) and reflects variations in the hydraulic energy of deposition, ranging from fine-grained decantation to higher-energy fluvial input of sand. Mud cracks suggest episodic drying events, although no evidence supports large-scale droughts. Both the lithofacies and the fossil record at 'Fazenda Tereza' indicate deposition in a freshwater environment under a warm climate.

The specimens described herein were recovered by processing claystone and siltstone samples from the lower portion of the succession (Fragoso *et al.* 2021). The fossil assemblage includes bioturbation, ostracods, spinicaudatans, actinopterygian remains (notably teeth and vertebrae of Amiidae), other hybodontiforms, abundant bone fragments of the coelacanthiform *Mawsonia gigas* and a single skeleton of the paramacellodid lizard *Neokotus sanfranciscanus* (Delicio *et al.* 1998; Carvalho & Maisey, 2008; Leite *et al.* 2018; Bittencourt *et al.* 2020, 2022; Fragoso *et al.* 2021).

The age of the Quiricó Formation is generally considered Barremian– Aptian, based on ostracods and palynomorphs from other areas of the Sanfranciscana Basin (Lima, 1979; Arai *et al.* 1995; Do Carmo *et al.* 2013; Bittencourt *et al.* 2015; Fauth *et al.* 2024). However, the age of the strata exposed at 'Fazenda Tereza' remains highly controversial. Carvalho and Maisey (2008) assigned the *Mawsonia*-bearing layers to the Berriasian, whereas recent research on ostracods has assigned the succession at 'Fazenda Tereza' to the Valanginian– Aptian interval (Leite *et al.* 2018, 2024). In this latter interpretation, it is unclear where *Mawsonia gigas* occurs. In addition, Coimbra (2020, 2023) has disputed the taxonomic identification of ostracods referred to *Cypridea*, rejecting the presence of pre-Barremian levels in the Quiricó Formation. Given the taxonomic controversy regarding the ostracods from the Quiricó Formation, and also the vertical range of *Mawsonia gigas* within the ostracod-based biostratigraphic framework of the 'Fazenda Tereza' locality, we will adopt a conservative approach and consider the Brazilian Lonchidiidae to be Barremian–Aptian in age pending further evidence.

# 3. Systematic Palaeontology

## 3.a. Lonchidionoides trifurcatum gen. et sp. nov. from Algeria

Chondrichthyes Huxley, 1880
Subclass Elasmobranchii Bonaparte, 1838
Cohort Euselachii Hay, 1902
Order Hybodontiformes Patterson, 1966
Family Lonchidiidae Herman, 1977
*Lonchidionoides* gen. nov.
ZooBank LSID. urn:lsid:zoobank.org:act:366E2C14-E128-483C-8AF6-6757F845DEA1.

*Etymology.* From the overall resemblance to the teeth of *Lonchidion*.

*Type species.* *Lonchidionoides trifurcatum* gen. et sp. nov.

*Diagnosis.* As for the type and the only known species.

*Lonchidionoides trifurcatum* gen. et sp. nov.

Figures 2 and 4

ZooBank LSID. urn:lsid:zoobank.org:act:82B30B56-BEB0-48B2-AB0F-C16A4E77C271.

*Etymology.* From the trident shape of the anterior teeth.

*Holotype.* Specimen LGEE-GH-SA-1, an anterior tooth (Figure 2c).

*Type locality and horizon.* 'Garet El Hemmam', Djebel Amour (central Saharan Atlas), Laghouat Province, Algeria; sample Gh11, upper part of the Tiout Formation (latest Albian–early Cenomanian in age), about 100 m below the base of the El Rhelida Formation.

*Referred material.* Five isolated teeth (specimens LGEE-GH-SA-2 to LGEE-GH-SA-6) from the type locality (Figure 2a, b, d–f). All specimens from the type horizon (sample Gh11), except LGEE-GH-SA-6 from an underlying layer (sample Gh9, located ~5 m above sample Gh11).

*Diagnosis.* Diminutive lonchidiid hybodont shark characterized by a dentition with a marked disjunct monognathic heterodonty; gracile, trident-shaped anterior teeth and low-cusped, more massively built posterior teeth; lateral teeth showing an intermediate morphology; no labial protuberance; narrow and rod-like shaped crown base; enameloid smooth and crown devoid of ornamentation.

*Description.* These teeth are minute, most of the specimens measuring less than 1 mm in width. All the specimens consist of well-preserved crowns with no preserved root structures. The basal face of the crown is depressed. Three main dental morphotypes can be distinguished, suggesting the existence of a disjunct monognathic heterodonty.

*Tooth morphotype I* (Figure 2a–c): this morphotype includes teeth (LGEE-GH-SA-1 to 3) with a markedly tricuspid (trident-shaped) crown. The erect main (central) cusp and the crescent-shaped lateral cusps are slender, especially in the holotype LGEE-GH-SA-1 (Figure 2c). The lateral cusps are slightly bent lingually. This morphotype is interpreted here as anterior teeth. One of these specimens (LGEE-GH-SA-2), showing a sub-symmetrical crown higher than wide, is interpreted as a symphysial tooth (Figure 2a). The lateral cusps are less projected laterally. In cross-section, the main cusp is subtriangular, with the crown more developed labially, whereas the lateral cusps are subcircular.

*Tooth morphotype II* (Figure 2d, e): this morphotype corresponds to teeth with less gracile tricuspid crown (LGEE-GH-SA-4 and LGEE-GH-SA-5). In a labiolingual view, the robust lateral cusps are triangular and project laterally. The notch between the main cusp and the distal cusp is more pronounced than on the mesial side. This morphotype is interpreted here as lateral teeth.

*Tooth morphotype III* (Figure 2f): this morphotype is represented by a significantly larger tooth with poorly individuated cusps (LGEE-GH-SA-6). The main cusp is broad and low, and the lateral cusps are reduced (cusplets). This morphotype is interpreted here as corresponding to posterior teeth, which include an enlarged one (interpreted here as the first posterior tooth) having a crushing function (as suggested by its functional wear).

## 3.b. Lonchidionoides sp. from Brazil

*Lonchidionoides* sp.

Figure 3

2021 ?Lonchidiidae, Fragoso *et al.* 2021, p. 1313, fig. 3c–f.

*Locality and horizon.* 'Fazenda Tereza' in João Pinheiro, Sanfranciscana Basin, Minas Gerais, Brazil; lower portion of the Quiricó Formation (Barremian–Aptian in age).

*Material.* Nine isolated teeth (specimens IGC-P 0093/1 to 0093/9) (Figure 3a–e).
<figure><img src="image_4.png" /><figcaption>**Figure 2.** Teeth of the hybodont shark *Lonchidionoides trifurcatum* gen. et sp. nov. from the uppermost Albian-lower Cenomanian fluvial deposits of 'Garet El Hemmam' (Algeria). (a1-a4), symphysial tooth (LGEE-GH-SA-2) in labial, basal, occlusal and lateral views; (b) anterior tooth (LGEE-GH-SA-3) in lingual view; (c1-c4) anterior tooth (holotype; LGEE-GH-SA-1) in labial, lingual, occlusal and lateral (mesial?) views; (d1-d4) lateral tooth (LGEE-GH-SA-4) in labial, lingual, occlusal and lateral (distal?) views; (e1-e4) lateral tooth (LGEE-GH-SA-5) in labial, lingual, occlusal and lateral (mesial?) views; (f1-f3) posterior tooth (LGEE-GH-SA-6) in labial, lingual and occlusal views. Scale bar equals 500 µm.</figcaption></figure>

*Description.* Some of the specimens were described and figured by Fragoso *et al.* (2021). The material available includes the tooth morphotypes II and III described above for the Algerian material. The morphotype I, characterized by a gracile trident-shaped crown, has not been recovered so far among the Brazilian specimens. The root is not preserved in all specimens.

Tooth morphotype II (Figure 3a): this morphotype is represented by one complete crown (IGC-P 0093/2), which is similar in shape and size to the Algerian specimen LGEE-GH-SA-5 (Figure 2e). In a labiolingual view, the distal cusp projects more laterally than the mesial cusp, and the notch that separates it from the main cusp is more marked. The basal part of the crown shows a well-developed rod-like portion.

Tooth morphotype III (Figure 3b-e): this morphotype includes a significantly larger crown (IGC-P 0093/9) (Figure 3b), which is

similar to the Algerian specimen LGEE-GH-SA-6 (Figure 2f) (interpreted here as the first posterior tooth). The cusps are abraded. The main cusp is broad and low, and the lateral cusps are reduced (cusplets). In addition, some smaller crowns (IGC-P 0093/1 and IGC-P 0093/7) are also assigned to this morphotype and interpreted here as more posterior teeth (Figure 3c, d). In a labiolingual view, the main cusp and lateral cusplets are low and pointed, and the occlusal crest is concave between these cusps. In the occlusal view, the main cusp and lateral cusplets slightly project labially and lingually, respectively. A minute crown (IGC-P 0093/8), showing similar morphological features, is interpreted as a posterior-most commissural tooth (Figure 3e). It mainly differs from the other teeth of this morphotype by the lateral cusplets that are closer to the main cusp, the occlusal crest that does not reach the main cusp apex and the base of the crown that is less constricted basally.
<figure><img src="image_5.png" /><figcaption>**Figure 3.** Teeth of the hybodont shark *Lonchidionoides* sp. from the Barremian-Aptian lacustrine deposits of 'Fazenda Tereza' (Brazil). (a1-a3), lateral tooth (IGC-P 0093/2) in labial, lingual and occlusal views; (b1-b3) posterior tooth (IGC-P 0093/9) in labial, lingual and occlusal views; (c1-c4) posterior tooth (IGC-P 0093/1) in labial, lingual, occlusal and basal views; (d1-d3) posterior tooth (IGC-P 0093/7) in labial, occlusal and basal views; (e1-e3) posteriormost tooth (IGC-P 0093/8) in labial, lingual and occlusal views. Scale bar equals 500 µm.</figcaption></figure>

# 4. Discussion

## 4.a. Comparisons

The material of *Lonchidionoides trifurcatum* gen. et sp. nov. from Algeria includes three main dental morphotypes, which are interpreted as representing distinct tooth positions (i.e. morphotype I: symphysial and anterior teeth; morphotype II: lateral teeth; morphotype III: posterior teeth). The material from Brazil includes some teeth that are almost identical in shape and size to some Algerian specimens (lateral and posterior tooth positions), thus strongly supporting its assignment to the new genus *Lonchidionoides*. The absence of trident-shaped anterior teeth (morphotype I) in the Brazilian material and of posteriormost teeth in the Algerian material is likely due to the small size of the available samples. However, the Brazilian specimens are left in open nomenclature (as *Lonchidionoides* sp.) pending the discovery of additional material, which would help to determine whether the North African and South American teeth represent a single or two species. The tooth root is unknown in both *Lonchidionoides*

trifurcatum and *Lonchidionoides* sp., as in most hybodontiform species based on isolated teeth (Böttcher, 2024).

*Lonchidionoides* is included here in the family Lonchidiidae based on its general morphological resemblance to *Lonchidion*. Although the anterior teeth of *Lonchidionoides* show a unique trident-shaped crown, the morphology of the lateral and posterior teeth is roughly similar to that of *Lonchidion* teeth (e.g. Rees & Underwood, 2002). Both taxa share some features (i.e. crown mesiodistally wider than high, crown shape subtriangular in occlusal view, base of the crown constricted, low to poorly defined cusps), but the latter has a more or less developed labial protuberance (= labial peg of some authors) that is absent in the former. Similarly, the teeth of the Triassic genus *Diplolonchidion* mainly differ from those of *Lonchidionoides* by the presence of two labial protuberances (Heckert, 2004). *Parvodus*, *Jiaodontus* and *Pristrisodus* have teeth with a labial protuberance, vertical folds and generally two or three pairs of lateral cusplets (Rees & Underwood, 2002; Klug et al. 2010; Bhat et al. 2018). *Luopingselache* has large teeth (up to 15 mm in
<figure><img src="image_6.png" /><figcaption>**Figure 4.** Tentative reconstruction of the lower dentition of *Lonchidionoides trifurcatum* gen. et sp. nov. from the uppermost Albian-lower Cenomanian of Algeria. Note that the material of *Lonchidionoides* sp. from the Barremian-Aptian of Brazil was used to supplement missing tooth positions (L3, P2, P3). Scale bar equals 1 mm.</figcaption></figure>

mesiodistal width) showing a labial protuberance, a strong ornamentation and up to six pairs of lateral cusplets (Wen *et al.* 2023). These features clearly distinguish *Parvodus*, *Jiaodontus*, *Pristrisodus* and *Luopingselache* from *Lonchidionoides*. *Vectiselachos* differs from *Lonchidionoides* by its larger, bulky teeth that are devoid of lateral cusplets and ornamented with folds and granulae (Rees & Underwood, 2002).

Several other hybodont genera (i.e. *Bahariyodon*, *Diabodus*, *Hylaeobatis*, *Isanodus*, *Lissodus*) have been tentatively referred to or excluded from the Lonchidiidae by various authors (see Rees & Underwood, 2002; Cuny *et al.* 2004, 2006, 2010; Fischer, 2008; Rees, 2008; Cappetta, 2012; Bhat *et al.* 2018; Wen *et al.* 2022, 2023). Regardless of the systematic position of these genera, their relatively large and massively built tooth crowns are easily distinguishable from those of *Lonchidionoides*. In addition, most of the species included in these genera have ornamented teeth.

Within the African-South American *Tribodus-Prihybodus* palaeobiogeographic province defined by Cuny (2012), *Lonchidionoides* is characterized by teeth that are clearly distinct from those of other unambiguous Early Cretaceous lonchidiids, which are represented only by *Lonchidion marocensis* from the ?Berriasian of Morocco (Duffin & Sigogneau-Russell, 1993; Rees & Underwood, 2002) and *Parvodus* sp. from the ?Early Cretaceous of Brazil (Cupello *et al.* 2012). As noted above, the latter two genera share the presence of a labial protuberance, which is lacking in *Lonchidionoides*.

### 4.b. Dentition reconstruction

Articulated dentitions of hybodontiforms indicate that enlarged lateral or posterior teeth with a crushing function were present in the monognathic heterodont dentitions of various taxa with a wide range of sizes, such as *Acrodus anningiae* (Day, 1864: pl. 3), *Acrodus georgii* (Rieppel, 1981: fig. 2), *Lissodus africanus* (Rees & Underwood, 2002: fig. 1), *Luopingselache striata* (Wen *et al.* 2023: fig. 2) and *Palaeobates polaris* (Romano & Brinkmann, 2010). Based on material consisting of isolated teeth, a similar type of dentition was also inferred for *Jiaodontus vedenemus* (Klug *et al.* 2010), *Lissodus nodosus* (Duffin, 1985: text-fig. 12), *Lissodus* sp. (Duncan, 2004: fig. 7), *Reticulodus synergus* (Voris & Heckert, 2017) and *Vectiselachos ornatus* (Rees & Underwood, 2002), among others. The different morphotypes recognized in *Lonchidionoides* suggest that this kind of monognathic heterodonty was also present in this genus, and a tentative reconstruction of the dentition of *Lonchidionoides* can thus be proposed. From the symphysis to the commissure, it is suggested that the lower jaw bears a symphysial tooth, two anterior, three lateral and three posterior teeth (Figure 4). According to this reconstruction, the

total number of tooth files present in the lower jaw would be estimated at 17. This is consistent with the tooth file number (lower jaw) known for various hybodont taxa, ranging from 15 to 21: one symphysial file and seven files on each side in *Palaeobates polaris* (Romano & Brinkmann, 2010); one symphysial file and eight files on each side in *Luopingselache striata* (Wen *et al.* 2023); one symphysial file and nine files on each side in *Acrodus anningiae* (Day, 1864), *Asteracanthus ornatissimus* (Stumpf *et al.* 2021), *'Polyacrodus' brevicostatus* (Patterson, 1966) and possibly *Lissodus africanus* (Rees & Underwood, 2002); and one symphysial file and ten files on each side in *Acrodus georgii* (Rieppel, 1981) and *Egertonodus basanus* (Maisey, 1983).

### 4.c. Dental features and diet inferences

The dentition of *Lonchidionoides* shows a strong disjunct monognathic heterodonty, well distinct from the moderate disjunct or gradient monognathic heterodonties observed in the above-mentioned hybodont genera. Moreover, the high degree of heterodonty of *Lonchidionoides* seems to be unique among hybodont taxa with dentitions of the clutching-crushing type. *Lonchidionoides* evolved a specialized dentition that clearly separates it from the European and North American lonchidiid genera (*Lonchidion*, *Parvodus*, *Vectiselachos*), which show a conservative dental morphology (Rees & Underwood, 2002; Cuny, 2012).

Some resemblances resulting from parallel evolution can be noted. Among non-euselachian elasmobranchs, trident-shaped teeth roughly similar to the anterior teeth of *Lonchidionoides* are known in some Palaeozoic phoebodonts (e.g. *Isacrodus*, *Jalodus*) and *xenacanths* (*Bransonella*) (Ginter, 2001; Ginter *et al.* 2002; Hampe & Ivanov, 2007; Ivanov *et al.* 2021). However, these early sharks had homodont or weakly heterodont dentitions, with no crushing posterior teeth. Among neoselachians, the reconstructed dentition of *Lonchidionoides* is somewhat similar (although much smaller) to that of young individuals of modern bullhead sharks (e.g. *Heterodontus portusjacksoni*; Reif, 1976: fig. 24c).

Non-marine hybodont sharks underwent a major diversification during the Early Cretaceous Period, resulting in a wide array of dental morphologies and trophic habits (Cuny *et al.* 2008, 2009; Cuny, 2012). The specialized dental morphology of *Lonchidionoides* suggests that these dwarf sharks seized minute, elusive prey items with their tricuspid anterior teeth and crushed them with their more massive, low-cusped posterior teeth. Hence, it is likely that microcrustaceans such as ostracods formed a large part of the diet of *Lonchidionoides*. These small shelled organisms are common to abundant in the beds that have yielded the shark teeth here described (Leite *et al.* 2018; M.B. pers. obs.). In modern
ecosystems, freshwater ostracods are predated by small teleost
fishes that can have similar tricuspid teeth (e.g. the cyprinodonti-
form *Cyprinodon brontotheroides*; Hernandez *et al.* 2018).

4.d. *Palaeobiogeographic significance*

The discovery of a new Cretaceous genus of non-marine hybodont
sharks occurring in both North Africa and South America further
documents the biogeographic history of fishes related to the
Gondwana break-up and South Atlantic opening (Maisey, 2000;
Capobianco & Friedman, 2019; Parméra *et al.* 2019). The original
distribution area of *Lonchidionoides* may have been divided into
two separate areas, possibly with subsequent vicariance (assuming
that the Brazilian and Algerian teeth represent two distinct
species). This aligns with the spatial distribution of other non-
marine cartilaginous and bony fish taxa such as the distobatid
sharks *Tribodus*, *Distobatus* and *Aegyptobatus* (Vullo &
Néraveau, 2008; Brito *et al.* 2025; Neves *et al.* 2025), the
holosteans *Calamopleurus* and *Obaichthys* (Forey & Grande, 1998;
Grande, 2010) and the coelacanths *Mawsonia* and *Axelrodichthys*
(Cavin, 2008). This faunal link is also supported by the occurrence
of loricarioid catfishes in the Cenomanian of North Africa (Brito
*et al.* 2024). Furthermore, *Lonchidionoides* adds to the list of non-
marine hybodont genera that appeared and diversified during the
Early Cretaceous Period, and it represents a new component of the
peculiar hybodont fauna characterizing the African–South
American *Tribodus–Priohybodus* province (Cuny *et al.* 2008;
Cuny, 2012).

5. Conclusion

A new genus of hybodontiform sharks, *Lonchidionoides*
(Lonchidiidae), is described here based on isolated teeth from
the uppermost Albian–lower Cenomanian of Algeria and the
Barremian– Aptian of Brazil. The distribution of this newly
recognized lonchidiid provides additional evidence of the biogeo-
graphic connection that existed between the non-marine ichthyо-
faunas of Africa and South America during the Late Jurassic–mid-
Cretaceous interval. In the Early to mid-Cretaceous ecosystems of
West Gondwana, ecological niche partitioning appears to have
occurred among synchronic and sympatric hybodonts. Medium-
sized distobatids with crushing or grinding dentitions coexisted
with the small-sized genus *Lonchidionoides*, which may have
occupied a specialized trophic niche as suggested by its unique,
delicate clutching–crushing dentition.

**Acknowledgements.** We thank L. Joanny (CMEBA, Rennes) for SEM images of the specimens from Algeria. We also thank J. Kriwet for his helpful comments that improved the manuscript. This research received funding from the Tellus-INTERRVIE programme of INSU-CNRS (R.V., project 'Vegace'), the FAPEMIG (J.S.B., grant APQ-00474-23), the CNPq (J.S.B., grant 313565/2021-0), the FAPESP (J.S.B., grant 2020/07997-4) and the Spanish Ministerio de Ciencia, Innovación y Universidades (A.P.-G., grant PID2023-148083NB-I00).

**Competing interests.** The authors declare none.

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