Hylaeochampsa

Hylaeochampsa is an extinct genus of eusuchian crocodylomorph. It is known only from a partial skull recovered from Barremian-age rocks of the Lower Cretaceous Vectis Formation (Wealden Group) of the Isle of Wight. This skull, BMNH R 177, is short and wide, with a eusuchian-like palate and inferred enlarged posterior teeth that would have been suitable for crushing. Hylaochampsa was described by Richard Owen in 1874, with H. vectiana as the type species. It may be the same genus as the slightly older Heterosuchus, inferred to have been of similar evolutionary grade, but there is no overlapping material as Heterosuchus is known only from vertebrae. If the two could be shown to be synonyms, Hylaeochampsa would have priority because it is the older name. Hylaeochampsa is the type genus of the family Hylaeochampsidae, which also includes Iharkutosuchus from the Late Cretaceous of Hungary. James Clark and Mark Norell positioned it as the sister group to Crocodylia.[1] Hylaeochampsa is currently the oldest known unambiguous eusuchian.[2]

Hylaeochampsa
Temporal range: Early Cretaceous
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Family: Hylaeochampsidae
Genus: Hylaeochampsa
Owen, 1874
Type species
Hylaeochampsa vectiana
Owen, 1874

References

  1. ^ Clark, James M.; Norell, Mark A. (1992). "The Early Cretaceous crocodylomorph Hylaeochampsa vectiana from the Wealden of the Isle of Wight" (pdf). American Museum Novitates. 3032.
  2. ^ Brochu, Christopher A. (2003). "Phylogenetic approaches toward crocodylian history". Annual Review of Earth and Planetary Sciences. 31: 357–397. doi:10.1146/annurev.earth.31.100901.141308.
Aegyptosuchidae

Aegyptosuchidae is an extinct family of eusuchian crocodyliforms from the Cretaceous period of Africa. They are characterized by their large size and flat heads. The family includes two genera, Aegyptosuchus and Aegisuchus.

Amphicotylus

Amphicotylus is an extinct genus of goniopholidid mesoeucrocodylian from the Tithonian of Colorado and Oklahoma.

Anteophthalmosuchus

Anteophthalmosuchus (meaning "forward-pointing eye crocodile") is an extinct genus of goniopholidid mesoeucrocodylian from the Early Cretaceous of southern England, eastern Spain, and western Belgium.

Batrachomimus

Batrachomimus is an extinct genus of neosuchian crocodyliform known from the Late Jurassic of northeastern Brazil. It contains a single species, Batrachomimus pastosbonensis, which was first described and named by Felipe C. Montefeltro, Hans C. E. Larsson, Marco A. G. de França and Max C. Langer in 2013. It is known from a nearly complete skull, osteoderms and limb bones. Batrachomimus belongs to the family Paralligatoridae and predates all other members of the family and its immediate sister group, Eusuchia, by 30 million years.

Coelosuchus

Coelosuchus is an extinct genus of goniopholidid mesoeucrocodylian. Fossils have been found from the Graneros Shale of the Benton Group in Wyoming, and are of Cenomanian age. It was slightly over 1 meter in length.

Eusuchia

The Eusuchia ("true crocodiles") are a clade of crocodylomorphs that first appears in the Early Cretaceous with Hylaeochampsa. Along with Dyrosauridae and Sebecosuchia, they were the only crocodyliformes who survived the K-T extinction. Since the other two clades died out 35 and 11 million years ago, all living crocodilian species are eusuchians, as are many extinct forms.

Heterosuchus

Heterosuchus is an extinct genus of crocodylomorph that may have been a eusuchian. It is known only from neck and back vertebrae recovered from Early Cretaceous-age rocks of the Hastings Beds (Wealden Group) of Hastings, Sussex. These vertebrae are procoelous (ball-and-socket articulation with the socket in front and the ball on the back of individual vertebrae), which is a trait of eusuchians. Heterosuchus was described by Harry Seeley in 1887, with H. valdensis as the type species. It may be the same genus as the slightly younger Hylaeochampsa, inferred to have been of similar evolutionary grade, but there is no overlapping material as Hylaeochampsa is known only from a partial skull; Hylaeochampsa would be the name used for both in that case, because it is the older name (coined in 1874). Because of the sparse material and apparent lack of distinguishing characteristics, James Clark and Mark Norell (1992) considered Heterosuchus a dubious name.

Hylaeochampsidae

Hylaeochampsidae is an extinct family of basal eusuchian crocodylomorphs thought to be closely related to the order Crocodylia. It was first constructed by Charles William Andrews in 1913 to include just one member: Hylaeochampsa. However, a new genus named Iharkutosuchus was described in 2007 and was found to be a sister taxon of Hylaeochampsa, and thus a member of the family Hylaeochampsidae. The genus Heterosuchus, named in 1887, may also be a member of the family. However, it is likely to be synonymous with Hylaeochampsa and has been considered a nomen dubium by James M. Clark and Mark Norell. Clark and Norell also claimed that there is no evidence to suggest that the two genera form a true clade distinct from other eusuchians, because remains associated with Heterosuchus are to fragmentary to show any clear phylogenetic relationship. A fourth genus called Pietraroiasuchus was assigned to Hylaeochampsidae in 2011. A phylogenetic analysis conducted with the description of Pietraroiasuchus also found Pachycheilosuchus to be part of the family.The family existed during the Cretaceous period in what is now Europe. Hylaeochampsa and its possible synonym Heterosuchus have both been found from the Vectis Formation of the Isle of Wight in England, dating back to the Barremian stage of the Early Cretaceous. Specimens of Iharkutosuchus have been found from the Csehbánya Formation in western Hungary, which was deposited during the Santonian stage of the Late Cretaceous. All hylaeochampsids had highly brevirostrine snouts and exhibited heterodonty, with large teeth concentrated posteriorly that were most likely adapted to crushing. In Iharkutosuchus these teeth were even multicusped. This is often characteristic of mammals but is highly unusual for a crocodylomorph, and suggests that the animal may have been herbivorous.

Karatausuchus

Karatausuchus is an extinct genus of atoposaurid crocodylomorph. It is known from a single specimen discovered in the Late Jurassic (Oxfordian - Kimmeridgian) Karabastau Svita from the vicinity of Mikhailovka in the Karatau Mountains of southern Kazakhstan. The type specimen is PIN 25858/1, a complete but poorly preserved juvenile skeleton with some possible soft tissue preservation. It is notable for having over 90 teeth, but its other anatomical details are difficult to discern. The length of this individual is estimated at 160 millimetres (6.3 in). Karatausuchus was described in 1976 by Mikhail Efimov, and the type species is K. sharovi.

Khoratosuchus

Khoratosuchus is an extinct genus of neosuchian crocodylomorph which existed in northeast Thailand during the early Cretaceous period. Its type species is Khoratosuchus jintasakuli. Khoratosuchus is the youngest and most advanced Mesozoic crocodyliform yet known from Thailand. It possesses several distinctive features that help determine its phylogenetic position among crocodylomorphs, including secondary choanae relatively posterior and almost encircled by the pterygoid bones on the palate and a smooth dorsal surface of the skull.

Nannosuchus

Nannosuchus (meaning "dwarf crocodile") is an extinct genus of goniopholidid mesoeucrocodylian from the Berriasian of England.

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.

Paluxysuchus

Paluxysuchus is an extinct genus of neosuchian crocodyliform known from the Early Cretaceous Twin Mountains Formation (late Aptian stage) of north-central Texas. It contains a single species, Paluxysuchus newmani. Paluxysuchus is one of three crocodyliforms known from the Early Cretaceous of Texas, the others being Pachycheilosuchus and an unnamed species referred to as the "Glen Rose Form". Paluxysuchus has a long, flat skull that is probably transitional between the long and narrow skulls of many early neosuchians and the short and flat skulls of later neosuchians.

Paralligatoridae

Paralligatoridae is an extinct family of neosuchian crocodyliforms that existed during the Jurassic and Cretaceous periods. It includes the genera Paralligator, Brillanceausuchus, Kansajsuchus, Shamosuchus, Scolomastax, Sabresuchus, Rugosuchus, Batrachomimus and Wannchampsus, as well as the yet-unnamed "Glen Rose form".

Pholidosaurus

Pholidosaurus is an extinct genus of neosuchian crocodylomorph. It is the type genus of the family Pholidosauridae. Fossils have been found in northwestern Germany. The genus is known to have existed during the Berriasian stage of the Early Cretaceous. Fossil material found from the Annero and Jydegård Formations in Skåne, Sweden and on the island of Bornholm, Denmark, have been referred to as a mesoeucrocodylian, and possibly represent the genus Pholidosaurus.

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.

Symptosuchus

Symptosuchus is an extinct genus of goniopholidid mesoeucrocodylian. It is known from the Late Cretaceous of Argentina. Argentine paleontologist Florentino Ameghino named the genus in 1899, along with the type species S. contortidens. It was formally described by Carlos Rusconi in 1934.

Wahasuchus

Wahasuchus is a genus of extinct mesoeucrocodylian of the Middle Campanian age found in the Quseir Formation, Egypt. The generic name derives from the Arabic word واحة (waha), which means "oasis", and souchos from the Greek in honor of crocodile-headed god of ancient Egypt. The specific egyptensis (Lat.) means from Egypt.Fossils of skull and jaw fragments, dorsal vertebrae, and fragmentary appendicular remains have been recovered.

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