Mesoeucrocodylia

Mesoeucrocodylia is the clade that includes Eusuchia and crocodyliforms formerly placed in the paraphyletic group Mesosuchia. The group appeared during the Early Jurassic, and continues to the present day.

Mesoeucrocodylia
Temporal range: Sinemurian - Recent, 199–0 Ma
Notosuchus BW
Notosuchus
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Crocodyliformes
Clade: Mesoeucrocodylia
Whetstone and Whybrow, 1983 [1]
Subgroups

Diagnosis

It was long known that Mesosuchia was an evolutionary grade,[1] a hypothesis confirmed by the phylogenetic analysis of Benton and Clark (1988) which demonstrated that Eusuchia (which includes all living crocodylian species) was nested within Mesosuchia. Due to the paraphyly of Mesosuchia, Mesoeucrocodylia was erected to replace Mesosuchia.

Several anatomical characteristics differentiate Mesoeucrocodylia from the other crocodylomorph clades. The frontal bones of the skull are fused together into a single compound element, for example. Mesoeucrocodylians possess something of a secondary palate, formed by the posterior extension of sutured palatine bones. The otic aperture of the members of this clade is blocked posteriorly by the squamosal bone.[2]

Classification

Phylogeny

Below is a cladogram from Fiorelli and Calvo (2007).[3]

Mesoeucrocodylia 

Fruitachampsa

Zosuchus

Sichuanosuchus

Shantungosuchus

Neuquensuchus

Hsisosuchus

 Metasuchia 

Neosuchia

Peirosauridae

Notosuchia

References

  1. ^ a b Whetstone KN, Whybrow PJ. 1983. A “cursorial” crocodilian from the Triassic of Lesotho (Basutoland), southern Africa. Occasional Papers of the Museum of Natural History. The University of Kansas 106: 1–37.
  2. ^ Clark, J. M. (1994). Patterns of evolution in Mesozoic Crocodyliformes In N.C. Fraser and H. D. Sues (editors), In the shadow of dinosaurs. Cambridge: Cambridge University Press. pp. 84–97.
  3. ^ Fiorelli LE, Calvo JO. 2007. The first "protosuchian" (Archosauria: Crocodyliformes) from the Cretaceous (Santonian) of Gondwana. Arquivos do Museu Nacional, Rio de Janeiro 65 (4): 417-459.
Araripesuchus

Araripesuchus is a genus of extinct crocodyliform that existed during the Cretaceous period of the late Mesozoic era some 125 to 66 million years ago. Six species of Araripesuchus are currently known. They are generally considered to be notosuchians (belonging to the clade Mesoeucrocodylia), characterized by their varied teeth types and distinct skull elements.

Caipirasuchus

Caipirasuchus is an extinct genus of sphagesaurid notosuchians known from the Late Cretaceous of northern São Paulo State, southeastern Brazil. The type species, C. paulistanus, was named in 2011. A second species, C. montealtensis, was referred to Caipirasuchus in 2013 after having been named in 2008 as a species of Sphagesaurus. A third species, C. stenognathus, was described in 2014. A fourth species, C. minerius, was described in 2018.

Chenanisuchus

Chenanisuchus ("Chenane crocodile") is a genus of dyrosaurid crocodyliform from the Late Cretaceous of Mali and the Late Palaeocene of Sidi Chenane in Morocco. It was described in 2005, after expeditions uncovered it in 2000.

The type species is C. lateroculi ("lateralis", lateral; "oculi", eyes), in reference to the laterally facing eyes.

Currently, Chenanisuchus is the most basal known dyrosaurid.

Chimaerasuchidae

Chimaerasuchidae ("Chimera crocodiles") is a family of mesoeucrocodylians. It was erected as a clade in 2004 by Carvalho et al and included Chimaerasuchus from the Early Cretaceous of China and Simosuchus from the Late Cretaceous of Madagascar. The validity of the clade has been questioned in later studies that found the two genera to be more distantly related.

Congosaurus

Congosaurus is an extinct genus of dyrosaurid mesoeucrocodylian. Fossils have been found from Lândana, in Angola and date back to the Paleocene epoch. In 1952 and 1964 Congosaurus was proposed to be synonymous with Dyrosaurus. The genus was later thought synonymous with Hyposaurus in 1976 and 1980. It has since been proven a distinct genus of dyrosaurid separate from both Dyrosaurus and Hyposaurus.In 2007, a new species of Congosaurus was constructed after previously being assigned to Rhabdognathus, and named C. compressus, extending the geographic range of the genus into the present-day Sahara. Lateromedially compressed teeth show its close relation to C. bequaerti.

Dakotasuchus

Dakotasuchus (meaning "Dakota [Sandstone] crocodile") is a genus of goniopholidid mesoeucrocodylian. Its fossils have been recovered from the Cenomanian-age Upper Cretaceous Dakota Sandstone of Kansas. The type specimen was found in an iron-cemented sandstone concretion near Salina. This concretion was broken into two large pieces; more of the specimen was probably present originally, but by the time it was found only the torso and short portions of the neck and tail remained. Twenty pairs of bony scutes ran down the midline of the back. The vertebrae lacked the procoelous articulation (concave anterior and convex posterior faces) of more derived crocodyliforms. Dakotasuchus had short broad shoulder blades, suggesting it had stout powerful forelimbs and perhaps terrestrial habits. M. G. Mehl, who described the genus, estimated the length of the type individual when complete to have been 3–4 metres (9.8–13.1 ft). The type species is D. kingi, named for Professor King, a former dean of Kansas Wesleyan University. Mehl did not classify his new genus to a more inclusive group than Mesosuchia (a paraphyletic group replaced by Mesoeucrocodylia). Robert Carroll assigned Dakotasuchus to Goniopholididae in 1988.

Fruitachampsa

Fruitachampsa is a genus of shartegosuchid crocodyliform from the Upper Jurassic Morrison Formation of Colorado. It is known from multiple specimens that show it to have been a relatively long-limbed terrestrial quadrupedal predator less than 1 metre (3.3 ft) long, with a short face and a prominent pair of canine-like teeth in the lower jaw. Before it was formally described in 2011, it was also known as the "Fruita form". Its type species is F. callisoni.

Hsisosuchus

Hsisosuchus is an extinct genus of crocodyliform from China. Currently there are three species within this genus: H. dashanpuensis is from the Middle Jurassic, while H. chungkingensis and H. chowi are from the Late Jurassic. . It is likely to have been a medium-sized predator (~3 meters in length).

Fossils of H. chungkingensis were found in the Shangshaximiao Formation (near Chongqing city). The holotype consists of the cranial skeleton and caudal osteoderms. A more complete specimen was found and described that added significant information on the postcranium of H. chungkingensis.H. dashanpuensis was found in the Xiashaximiao Formation.H. chowi was found in the Shangshaximiao Formation. The holotype specimen consists of a nearly complete skull (25 cm long), mandibles, most of the vertebral column, partial pectoral and pelvic girdles, most of the forelimbs, fragments of hindlimbs and many osteoderms. It differs from other species of Hsisosuchus in several features of its skull and postcrania.

Mariliasuchus

Mariliasuchus ("Marilia crocodile") is an extinct genus of Late Cretaceous notosuchian mesoeucrocodylian found near Marilia, Brazil. The first bone remains were found and collected in 1995 by Brazilian paleontologist William Nava, in red rocks from the fossiliferous Adamantina Formation. Four years later, it was described as Mariliasuchus amarali, by Brazilian paleontologists Ismar de Souza Carvalho and Reinaldo J. Bertini.

Its type species M. amarali, in honour of Sérgio Estanislaw do Amaral, Brazilian naturalist. A second species, M. robustus, was named in 2007.

Metasuchia

Metasuchia is a major clade within the superorder Crocodylomorpha. It is split into two main groups, Notosuchia and Neosuchia. Notosuchia is an extinct group that contains primarily small-bodied Cretaceous taxa with heterodont dentition. Neosuchia includes the extant crocodylians and basal taxa, such as peirosaurids and pholidosaurids. It is phylogenetically defined by Sereno et al. (2001) as a clade containing Notosuchus terrestris, Crocodylus niloticus, and all descendants of their common ancestor.

Neosuchia

Neosuchia is a clade within Mesoeucrocodylia that includes all modern extant crocodilians and their closest fossil relatives. It is defined as the most inclusive clade containing all crocodylomorphs more closely related to Crocodylus niloticus (the Nile Crocodile) than to Notosuchus terrestris. Neosuchia is very diverse and may be polyphyletic, as the clade has undergone many revisions since it was first named in 1988. Neosuchians first appear in the Early Jurassic with the earliest known goniopholid Calsoyasuchus, which lived during the Sinemurian and Pliensbachian stages.

Pabwehshi

Pabwehshi (meaning "Pab [Formation] beast ["wehshi" in Urdu]") is an extinct genus of mesoeucrocodylian. It is based on GSP-UM 2000, a partial snout and corresponding lower jaw elements, with another snout assigned to it. These specimens were found in Maastrichtian-age Upper Cretaceous rocks of the Pab Formation in Balochistan, Pakistan, and represent the first diagnostic crocodyliform fossils from Cretaceous rocks of South Asia. Pabwehshi had serrated interlocking teeth in its snout that formed a "zig-zag" cutting edge. Pabwehshi was named in 2001 by Jeffrey A. Wilson and colleagues. The type species is P. pakistanensis, in reference to the nation where it was found. It was traditionally classified as a baurusuchid closely related to Cynodontosuchus and Baurusuchus. Larsson and Sues (2007) found close affinity between Pabwehshi and the Peirosauridae within Sebecia. Montefeltro et al. Pabwehshi has a sagittal torus on its maxillary palatal shelves – a character that is absent in baurusuchids – but they did not include Pabwehshi in their phylogenetic analysis.

Peirosauridae

Peirosauridae is a Gondwanan family of mesoeucrocodylians that lived during the Cretaceous period. It was a clade of terrestrial crocodyliforms that evolved a rather dog-like form, and were terrestrial carnivores. It was phylogenetically defined in 2004 as the most recent common ancestor of Peirosaurus and Lomasuchinae and all of its descendants. Lomasuchinae is a subfamily of peirosaurids that includes the genus Lomasuchus.Lomasuchinae was defined in the same 2004 study as the most recent common ancestor of Lomasuchus and Mahajangasuchini and all of its descendants. Mahajangasuchini, also constructed in the study, was defined as the most recent common ancestor of Mahajangasuchus and Uberabasuchus and all of its descendants. However, all more recent phylogenetic analyses placed Mahajangasuchus within its own family, Mahajangasuchidae, along with the newly named Kaprosuchus.

Rhabdognathus

Rhabdognathus is an extinct genus of dyrosaurid crocodylomorph. It is known from rocks dating to the Paleocene epoch from western Africa, and specimens dating back to the Maastrichtian era were identified in 2008. It was named by Swinton in 1930 for a lower jaw fragment from Nigeria. The type species is Rhabdognathus rarus. Stéphane Jouve subsequently assessed R. rarus as indeterminate at the species level, but not at the genus level, and thus dubious. Two skulls which were assigned to the genus Rhabdognathus but which could not be shown to be identical to R. rarus were given new species: R. aslerensis and R. keiniensis, both from Mali. The genus formerly contained the species Rhabdognathus compressus, which was reassigned to Congosaurus compressus after analysis of the lower jaw of a specimen found that it was more similar to that of the species Congosaurus bequaerti. Rhabdognathus is believed to be the closest relative to the extinct Atlantosuchus.

Shartegosuchidae

Shartegosuchidae is an extinct family of Late Jurassic and Early Cretaceous crocodylomorphs. The family is named after the Late Jurassic Shar Teeg Beds in southwestern Mongolia, from which most shartegosuchid remains have been found. Five genera are currently assigned to Shartegosuchidae: Shartegosuchus, Nominosuchus, Kyasuchus, Adzhosuchus, and Fruitachampsa. Shartegosuchus, Nominosuchus, and Adzhosuchus all come from Shar Teeg, while Kyasuchus is known from the Early Cretaceous of Russia. Fruitachampsa is known from the Late Jurassic Morrison Formation of the western United States.

Sphagesauridae

Sphagesauridae is a Gondwanan family of mesoeucrocodylians that lived during the Late Cretaceous. It was a clade of terrestrial crocodilians that evolved very mammal-like teeth and jaws. Both Sphagesaurus and Adamantinasuchus are known from the Turonian to Santonian of Brazil.

Susisuchus

Susisuchus is an extinct genus of neosuchian mesoeucrocodylian crocodyliform from the Early Cretaceous of Brazil. Fossils have been found from the Nova Olinda Member of the Aptian-age Crato Formation in the Araripe and Lima Campos Basins of northeastern Brazil. Named in 2003, Susisuchus is the sole member of the family Susisuchidae, and is closely related to the clade Eusuchia, which includes living crocodilians. The type species is S. anatoceps, known from a single partial articulated skeleton that preserves some soft tissue. A second species, S. jaguaribensis, was named in 2009 from fragmentary remains.

Terminonaris

Terminonaris is a genus of extinct pholidosaurid crocodyliforms that lived in the Late Cretaceous (Cenomanian and Turonian). The name means: “enlarged snout or nose” at the front of the skull. Terminonaris is an early crocodile, within a subgroup called Mesoeucrocodylia. Its remains have only been found in North America and Europe. Originally known under the generic name Teleorhinus, it was once believed to be a teleosaurid (a family of marine gavial-like thalattosuchians). Both, prehistoric crocodiles such as Terminonaris as well as modern crocodiles belong to the same group called crocodyliformes, although modern crocodiles have specific features that show indicate distant relatives of this species and in the subgroup Eusuchia.

Major groups within Mesoeucrocodylia
Notosuchia
Sebecia
Neosuchia
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