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A Giant Crocodile from the Plio-Pleistocene of Kenya, the Phylogenetic Relationships of Neogene African Crocodylines, and the Antiquity of Crocodylus in Africa
Journal of Verterbrate Paleontology
Abstract and Figures
We describe a new crocodile, Crocodylus thorbjarnarsoni, sp. nov., on the basis of skulls and jaws from Pliocene and Pleistocene deposits in the Lake Turkana Basin of Kenya. The new species has a comparatively broad, deep snout and resembles an extinct horned crocodile from the Quaternary of Olduvai Gorge (C. anthropophagus), but the squamosal ‘horns’ are not as well developed. The skull table has a strongly trapezoidal outline different from those of the living Nile crocodile (C. niloticus) and crocodiles from late Miocene deposits in the Turkana Basin. The largest specimens are from animals up to 7.5 m in total length. It would have been the largest predator in its environment, and the early humans found in the same deposits were presumably part of its prey base. A phylogenetic analysis, including the new species and an improved sample of extinct crocodyline diversity, suggests a more complex phylogenetic and biogeographic history for the clade in Africa and the eastern Indian Ocean region than previously supposed. The analysis limits the known geographic and stratigraphic range of Rimasuchus lloydi, previously thought to occur throughout Africa from the early Miocene through the Pleistocene of northern Africa. Crocodylus niloticus is not known with certainty from units older than the Quaternary, and most late Miocene fossils from the Turkana Basin previously referred to C. niloticus can instead be referred to C. checchiai. The current first appearance datum for Crocodylus in Africa is approximately 7 Ma.
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... Molecular and paleontological data have established that Crocodylus (Figs. 7.13B and 7.15A) first appeared during the Neogene, with the oldest known fossil occurrences from the Miocene-Pliocene of Africa and the Indian subcontinent (Oaks, 2011;Brochu & Storrs, 2012). The largest known species of Crocodylus, C. thorbjarnarsoni, from the Neogene (Pliocene) and Quaternary (Pleistocene) of Kenya, attained a total length of 7.5 m (Brochu & Storrs, 2012). ...
... Molecular and paleontological data have established that Crocodylus (Figs. 7.13B and 7.15A) first appeared during the Neogene, with the oldest known fossil occurrences from the Miocene-Pliocene of Africa and the Indian subcontinent (Oaks, 2011;Brochu & Storrs, 2012). The largest known species of Crocodylus, C. thorbjarnarsoni, from the Neogene (Pliocene) and Quaternary (Pleistocene) of Kenya, attained a total length of 7.5 m (Brochu & Storrs, 2012). By comparison, the largest present-day species is Crocodylus porosus (saltwater crocodile) from the Indo-Pacific region, with a reliably recorded maximum length of about 6.2 m (Grigg & Kirshner, 2015). ...
... Its slender tooth crowns each bear mesial and distal keels (Storrs, 2003). Euthecodon attained a skull length of up to 1.5 m and a total length of up to at least 7 m (Brochu & Storrs, 2012). Brochu (2007a) placed it in Osteolaeminae, but Conrad et al. (2013) argued that it is more closely related to the extant slender-snouted crocodyline (Mecistops cataphractus). ...
... Although recent phylogenetic analyses have not revealed a monophyletic clade for the "Asiatosuchus-like taxa" (Boerman et al., 2022;Brochu, 2013;Brochu & Storrs, 2012;Delfino & Smith, 2009;Jouve, 2016;Wang et al., 2016), most species related to this genus are traditionally considered basal crocodyloids. Cladograms generally recovered A. grangeri, A. germanicus, "Crocodylus" affinis, and "Crocodylus" depressifrons as the earliest branched crocodyloids, while "A. ...
... Only material from this type locality has been included in this study. To determine the phylogenetic relationships of the species to which they belong, their morphological characters were scored in the data matrix proposed by Narv aez et al. (2021), based on that developed by Brochu and Storrs (2012) (see Data S1). ...
... The analysis performed here recovered 11,608 most parsimonious trees of 781 evolutionary steps, with a Consistency Index (CI) of 0.312, and a Retention Index (RI) of 0.790. The topology of the strict consensus tree ( Figure 5) is mostly consistent with that obtained from previous morphological analyses of Eusuchia and Crocodylia (Brochu, 2013;Brochu & Storrs, 2012;Buscalioni et al., 2011;Delfino & Smith, 2009;Jouve et al., 2019;Narv aez et al., 2016Narv aez et al., , 2021Puértolas-Pascual et al., 2014Rio & Mannion, 2021;Ristevski et al., 2021;Wu et al., 2023). The closest relatives of Crocodylia in this study are the allodaposuchids, as in the phylogenetic analysis of Narv aez et al. (2021). ...
The eusuchian crocodyliforms recorded in the Eocene levels of the Spanish Duero Basin belong to three lineages: Planocraniidae, with the species Duerosuchus piscator ; Alligatoroidea, represented by several specimens of the genus Diplocynodon ; and Crocodyloidea, which includes several specimens traditionally attributed to Asiatosuchus . The genus Asiatosuchus , established in 1940 based on a middle Eocene species from Mongolia, has subsequently served as a wastebasket taxon for Paleogene remains belonging to several species, not only from Asia but also belonging to the European and North American records. Many of these species are known by highly fragmentary remains, sharing the presence of characters such as a flat and triangular skull, and long symphyses in the lower jaw, recognized as characteristic for the crocodyloids. In addition to isolated cranial remains, among the material traditionally attributed to Asiatosuchus at the Duero Basin stands out a nearly complete skull and a left mandible, from the middle Eocene area of Casaseca de Campeán (Zamora Province). The present study analyses in detail these specimens, previously reported during the 1980s, but analyzed in a very preliminary way. They are included for the first time in a phylogenetic analysis to establish the systematic position of this Spanish form. The results confirm that it corresponds to a new species of basal crocodyloid, defined here as Asiatosuchus oenotriensis sp. nov.
... All other gavialoids have a maxillary palate that is dorsally positioned in relation to the maxillary alveoli (Hua & Jouve, 2004;Jouve, 2016;Rio & Mannion, 2021). Both Sutekhsuchus and Tomistoma schlegelii possess a maxilla-palatine suture that intersects the suborbital fenestra at the latter's anteromedial margin, which differs to Gavialis and other later diverging gavialines in which the suture intersects at the anterior corner (Brochu & Storrs, 2012;Rio & Mannion, 2021). Most South American gavialoids (e.g. ...
For decades, the interrelationships of the extant crocodylians Gavialis gangeticus and Tomistoma schlegelii have been debated, with only recent morphological phylogenetic analyses recovering the sister-taxon relationship between these two gavialoid species that has long been apparent in topologies based on molecular data. Several extinct species from the Mediterranean region are currently assigned to Tomistoma; however, their phylogenetic placement is labile, and often they do not form a clade with Tomistoma schlegelii. Here, we present a revision of Tomistoma dowsoni from the Early Miocene of Egypt and Libya, based on the type specimen (a partial snout and mandible) and referred material, including a nearly complete skull. These specimens show no notable anatomical differences and diagnostic features include: (1) a heart-shaped naris; (2) a prefrontal and lacrimal that are equidimensional in anteroposterior length; and (3) a prominent posterior process of the supraoccipital with a convex posterior margin. Maximum parsimony analysis, under both equal and extended implied weighting, recovers Tomistoma dowsoni as a phylogenetically nested gavialine, distantly related to Tomistoma schlegelii and other Mediterranean species currently referred to Tomistoma. Instead, Tomistoma dowsoni forms a sister-taxon relationship with Eogavialis andrewsi, from the Late Miocene of Kenya. Given that this clade does not consistently cluster with the type species of Eogavialis, and that Tomistoma dowsoni is diagnostic and clearly not referrable to Tomistoma, we herein erect the genus Sutekhsuchus, with the new combination Sutekhsuchus dowsoni. Our phylogenetic analyses recover the European Miocene gavialoids in a monophyletic group with the North American Thecachampsa, forming a clade of early-diverging gavialines that underwent transoceanic dispersal. We also recover a monophyletic group of thoracosaurs, comprising Eothoracosaurus, Portugalosuchus, and Thoracosaurus, which is expanded to include other Late Cretaceous-Early Paleogene European, North American, and North African species under extended implied weighting. https://zoobank.org/urn:lsid:zoobank.org:pub:2DE71417-8088-4749-8672-72E4A40C0B39
... In E. lerichei, the maxilla-palatine suture intersects the suborbital fenestra at the anterior corner, as in Thoracosaurus isorhynchus, Gavialis, and many other latediverging gavialoids. In Eosuchus minor, the maxilla-palatine suture intersects the suborbital fenestra at the anteromedial margin, as in Eothoracosaurus and Tomistoma schlegelii (Brochu, 2004(Brochu, , 2006Brochu & Storrs, 2012;Piveteau, 1927;Rio & Mannion, 2021). ...
Eosuchus lerichei is a gavialoid crocodylian from late Paleocene marine deposits of northwestern Europe, known from a skull and lower jaws, as well as postcrania. Its sister taxon relationship with the approximately contemporaneous species Eosuchus minor from the east coast of the USA has been explained through transoceanic dispersal, indicating a capability for salt excretion that is absent in extant gavialoids. However, there is currently no anatomical evidence to support marine adaptation in extinct gavialoids. Furthermore, the placement of Eosuchus within Gavialoidea is labile, with some analyses supporting affinities with the Late Cretaceous to early Paleogene “thoracosaurs.” Here we present novel data on the internal and external anatomy of the skull of E. lerichei that enables a revised diagnosis, with 6 autapormorphies identified for the genus and 10 features that enable differentiation of the species from Eosuchus minor. Our phylogenetic analyses recover Eosuchus as an early diverging gavialid gavialoid that is not part of the “thoracosaur” group. In addition to thickened semi‐circular canal walls of the endosseous labyrinth and paratympanic sinus reduction, we identify potential osteological correlates for salt glands in the internal surface of the prefrontal and lacrimal bones of E. lerichei. These salt glands potentially provide anatomical evidence for the capability of transoceanic dispersal within Eosuchus, and we also identify them in the Late Cretaceous “thoracosaur” Portugalosuchus. Given that the earliest diverging and stratigraphically oldest gavialoids either have evidence for a nasal salt gland and/or have been recovered from marine deposits, this suggests the capacity for salt excretion might be ancestral for Gavialoidea. Mapping osteological and geological evidence for marine adaptation onto a phylogeny indicates that there was probably more than one independent loss/reduction in the capacity for salt excretion in gavialoids.
... The Italian Peninsula did not differ from the rest of the continent, as the crocodylian record from Miocene localities is represented by an extensive number of disarticulated material and isolated teeth referred to either crocodylids or tomistomines (Del Vecchio, 1921;Kotsakis et al., 2004;Zoboli et al., 2019). While the presence of tomistomines in the Mediterranean arch of Europe is known since the Paleogene (Piras et al., 2007;Nicholl et al., 2020), the biogeographic radiation of crocodylids (namely Crocodylus spp.) is restricted to the Late Miocene and subsequent periods: the earliest fossil occurrences in Europe date back to the Messinian Delfino & Rook, 2008;Brochu & Storrs, 2012). The endemic European Diplocynodon, conversely, became extinct in the Middle Miocene, as attested by the fossils recovered from the Early to Middle Miocene of European mainland and Iberian Peninsula (Martin & Gross, 2011;Aráez et al., 2017;Lujàn et al., 2019;Chroust et al., 2021; Kriwet et al., 2016) in left lateral (a1), right lateral (a2), anterior (a3) and basal (a4) views. ...
The holotype and only specimen referred to the Early Miocene shark Acanthias bicarinatus Sismonda, 1849 is housed in the collections of the Museo di Geologia e Paleontologia dell’Università degli Studi di Torino and was collected from the serpentinite sandstone of the middle-late Burdigalian Termofourà Formation of the Torino Hill. The specimen, formerly interpreted as a fragment of a squalid dorsal-fin spine, is reinterpreted herein as an isolated crocodylian tooth. The validity of the species Acanthias bicarinatus is therefore reconsidered and referred to as a nomen dubium. The tooth, replaced while the crocodylian was alive, was deposited in a near-shore marine environment at a time when modern crocodylian lineages were already widespread along the northern sector of the Mediterranean area.
Skulls are a critical part of the crocodile through which we can distinguish between the different genera and species. Most of the crocodiles which previously studied from the Eocene–Oligocene to the Miocene times in Egypt were concerned with the identification of the genus and sometimes on the species without a detailed focusing on the evolution, comparing between them and trying to determine the ancestor or the closest species of them to the living crocodile in Egypt. The only known living species of Crocodylus in Egypt is Crocodylus niloticus which inhabits Lake Nasser in Aswan, southern of Egypt. From the Cenozoic era, broad snouted crocodiles diversity had been reported in Egypt. About 35 million years ago, through the Eocene epoch, the crocodilian fossils from Fayum provided evidence of the diversity of crocodile species including Crocodylus articeps and Crocodylus megarhinus. In addition to that, throughout the Early Miocene epoch, from about 18 million years ago, in Wadi Moghra Egypt crocodilian fossils demonstrate another diversity, extended to the first appearance of Rimasuchus lloydi which placed inside the Osteolaeminae later. By various measurements and carefully morphological examination of the different species recorded from Egypt, it was found that there are high levels of variation in morphology of the skulls including their dimensions, and the sutures shapes especially between premaxilla and maxilla ventrally and also between maxilla and palatine, as well as the extension of the maxillary ramus of the ectopterygoid. Using cluster analysis, it is proven that Eocene Crocodylus is the ancestor to all known broad snouted species recorded from Egypt since the Eocene time. The closest species to the Eocene specimen is the living Crocodylusniloticus. That in fact make that most of the broad snouted crocodiles in Egypt are endemic.
Fossil crocodylian remains have been documented from India and other parts of South Asia since the mid-19th century, but specimens attributed to several extinct and extant species of Crocodylus have largely been neglected in modern taxonomic treatments. Here, we present a detailed anatomical description of the extinct species Crocodylus palaeindicus, which we restrict to the Late Miocene to early Middle Pleistocene of India. Using an autapomorphy-based approach to species-level identification, we regard Crocodylus sivalensis as a junior synonym of C. palaeindicus, and provide taxonomic reidentifications of all specimens previously referred to these two species. We present a new diagnosis for C. palaeindicus that facilitates its distinction from the extant mugger crocodile, C. palustris, which does not unequivocally appear in the fossil record prior to the Pleistocene. The lack of clear spatiotemporal overlap, coupled with the otherwise lengthy ghost lineage implied by their sister taxon relationship in our phylogenetic analyses, provides tentative support that the extant species is either the descendant of C. palaeindicus, or originated via budding cladogenesis. An expanded phylogenetic analysis recovers the Late Miocene African C. checchiai and Pliocene South American C. falconensis as species within the Neotropical Crocodylus clade, supporting an African origin for this radiation. We also recover Kinyang, from the Early–Middle Miocene of Kenya, as a crocodyline, rather than an osteolaemine as originally described, and it is potentially the stratigraphically earliest known member of the Crocodylus lineage. Other notable results from our phylogenetic analyses suggest that crocodyloids might not have been present in North America prior to the late Neogene arrival of Crocodylus, with Albertosuchus knudsenii, Prodiplocynodon langi, and ‘Crocodylus’ affinis all recovered outside of Crocodyloidea. Furthermore, we demonstrate that an alligatoroid placement for the recently erected latest Cretaceous–Paleogene East Asian clade Orientalosuchina is highly labile, with relationships at the ‘base’ of Crocodylia unstable.
This study adopts a new approach describing palaeohydrology and palaeoclimates based on the interpretation of stable oxygen isotopes (δ18Op) recorded in fossil crocodilian teeth. They represent an archive of prime interest for tracking freshwater palaeoenvironmental change, applicable to many palaeontological localities in the world: crocodilian teeth are abundant in continental basins and have been widely distributed since their diversification during the Mesozoic; the enamel phosphate is resistant to diagenesis and retains its original isotopic composition over geological timescales; and their δ18Op mainly relies on that of the crocodilian's home waterbody (δ18Ow), which in turn reflects waterbody types, regional climate, and evaporation conditions. This study presents the first application of this theoretical interpretative model to the Shungura Formation (Lower Omo Valley, Ethiopia), a key witness of the important environmental change in eastern Africa during the Plio-Pleistocene that impacted the evolution of regional faunas, including humans. In this complex and variable environmental context, the δ18Op of coexisting crocodilians allows for the fingerprinting of the diversity of aquatic environments they had access to at a local scale. This study sheds light on two important results: the δ18Op of crocodilian teeth (1) indicates stable aquatic environments in the northern Turkana Depression from 2.97 to ca. 2.57 Ma but a decline in local waterbodies diversity after 2.32 Ma, suggesting increasing aridity, and (2) shows, like previous geochemical studies on palaeosols and bivalves in the area, a significant increase in δ18Ow from 2.97 to ca. 1.14 Ma, likely due to the shifting air stream convergence zones between the West African and Indian Summer Monsoons and/or reduced rainfall over the Ethiopian Highlands.
Voay robustus, the extinct Malagasy “horned” crocodile, was originally considered to be the only crocodylian representative in Madagascar during most part of the Holocene. However, Malagasy crocodylian remains have had confused taxonomic attributions and recent studies have underlined that Crocodylus and Voay populations coexisted on the island for at least 7500 years. Here, we describe the inner braincase anatomy of Voay robustus using x‐ray computed tomography on four specimens, to provide new anatomical information that distinguishes Voay from Crocodylus, especially features of the brain endocast and the paratympanic sinuses. Geometric morphometric analyses are performed on 3D models of the internal organs to compare statistically Voay with a subset of extant Crocodylidae. Following these comparisons, we build an endocranial morphological matrix to discuss the proposed phylogenetic affinities of Voay with Osteolaeminae from an endocranial point of view. Additionally, we discuss the use of internal characters in systematic studies and find that they can have a major impact on morphological analyses. Finally, new radiocarbon data on Voay and subfossil Crocodylus specimens are recovered between 2010 and 2750 cal BP, which confirm the cohabitation of the two species in the same area for a long period of time. We thus assess several extinction scenarios, and propose a slightly different ecology of Voay compared to Crocodylus, which could have allowed habitat partitioning on the island. Our approach complements information obtained from previous molecular and morphological phylogenies, as well as previous radiocarbon dating, together revealing past diversity and faunal turnovers in Madagascar.
Description of new species of the Crocodilian genus Euthecodon . E. arambourgi, from the Burdigalian of Libya. Considerations upon the evolution of the genus which is known from the Burdigalian to the Villafranchian in Africa. The genus seems to have its roots in the Crocodylinae rather than the Tomistominae.
Fossil crocodiles are common in proto-Orange River deposits of Namibia, of Lower and Middle Miocene age. They are also known from the Middle Miocene of the Koa River Valley at Bosluis Pan, Namaqualand, South Africa. The species is closest in overall morphology to the extinct species Crocodylus lloydi, known from Lower and Middle Miocene deposits of North Africa, and the Plio-Pleistocene of East Africa, but in some characters it is close to the extant species Crocodylus niloticus. These records extend the geographic range of crocodiles in Africa considerably to the south of their present day distribution limits. The presence of crocodiles in southern Namibia and South Africa suggests that this part of the continent was tropical to subtropical during the Lower and basal Middle Miocene, in strong contrast to its temperate nature today.