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.
|Skull of Sebecus icaeorhinus|
Benton and Clark, 1988
The phylogeny of basal metasuchians has experienced many revisions in recent years. The phylogeny of notosuchians has been particularly revised, with the construction of Sebecia by Larsson and Sues (2007) to include peirosaurids in the clade. Previously, peirosaurids were placed outside Notosuchia. Larsson and Sues (2007) also suggested that Sebecosuchia (containing the families Baurusuchidae and Sebecidae) was polyphyletic, as Baurusuchus was placed outside Sebecia, which itself was placed outside Notosuchia. However, more recent phylogenetic studies have placed Baurusuchus within Notosuchia once again, although it is still not considered to be a sebecosuchian.
In 2012, a phylogenetic study was done to produce supertrees of Crocodyliformes, including 184 species. The most parsimonious trees were highly resolved, meaning the phylogenetic relationships found in the analysis were highly likely. As such, below is the consensus tree from the study, focusing on the Metasuchian branch of the tree.
Adzhosuchus is an extinct genus of crocodylomorph in the family Shartegosuchidae. Fossils have been found from southwestern Mongolia that date back to the Late Jurassic period.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.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.Baurusuchidae
Baurusuchidae is a Gondwanan family of mesoeucrocodylians that lived during the Late Cretaceous. It is a group of terrestrial hypercarnivorous crocodilians from South America (Argentina and Brazil) and possibly Pakistan. Baurusuchidae has been defined as a clade containing the most recent common ancestor of Baurusuchus and Stratiotosuchus and all of its descendants. It may, however, be polyphyletic, as recent phylogenetic analyses have placed Baurusuchus within Notosuchia and other baurusuchids within the more distantly related clade Sebecia. A recent study of the family finds it monophyletic by including the South American genera Baurusuchus, Cynodontosuchus, Pissarrachampsa, Stratiotosuchus, and Wargosuchus. Other traditional baurusuchids like Pabwehshi are excluded. The recently named Campinasuchus is also included in the family. Baurusuchids have been placed in the suborder Baurusuchia, and two subfamilies have been proposed: Baurusuchinae and Pissarrachampsinae.Dolichobrachium
Dolichobrachium is a dubious genus of extinct poposaurid crurotarsan. Fossils have been found from the Popo Agie Formation in Wyoming and are of Late Triassic age. It was one of the first rauisuchians to have been named.Doratodon
Doratodon is an extinct genus of Late Cretaceous crocodylomorph that was once believed to be a dinosaur.Eremosuchus
Eremosuchus is an extinct genus of sebecosuchian mesoeucrocodylian. Fossils have been found from El Kohol, Algeria of Eocene age. It had serrated, ziphodont teeth.
The genus was originally referred to the family Trematochampsidae in 1989. A close relation to the baurusuchids was also considered. However, it was only tentatively assigned to this family on the basis of a few features of the cranial skeleton. Some features, such as a broad concave symphysis and laterally compressed teeth, are not restricted to the trematochampsids and occur in some sebecosuchians such as Baurusuchus and Sebecus. Other features such as the surangular forming part of the craniomandibular articulation can also be found in many basal mesoeucrocodylians. A later phylogenetic analysis placed Eremosuchus within the suborder Sebecosuchia. It is now thought to be one of many putatively assigned sebecosuchians that cannot be firmly placed within any one family. It is thought to be the closest relative of the genus Pehuenchesuchus.Ilchunaia
Ilchunaia is an extinct genus of sebecid mesoeucrocodylian. Fossils have been found from the Divisadero Largo Formation of Argentina dating back to the Late Eocene, and a locality in Mendoza, Argentina dating back to the Oligocene. Little material is known from the genus, with only the anterior portion of the skull being present to study (the holotype has since been lost).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.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.Notosuchia
Notosuchia is a suborder of primarily Gondwanan mesoeucrocodylian crocodylomorphs that lived during the Jurassic and Cretaceous. Some phylogenies recover Sebecosuchia as a clade within Notosuchia, others as a sister group (see below); if Sebecosuchia is included within Notosuchia its existence is pushed into the Middle Miocene, about 11 million years ago. Fossils have been found from South America, Africa, Asia, and Europe. Notosuchia was a clade of terrestrial crocodilians that evolved a range of feeding behaviours, including herbivory (Chimaerasuchus), omnivory (Simosuchus), and terrestrial hypercarnivory (Baurusuchus). It included many members with highly derived traits unusual for crocodylomorphs, including mammal-like teeth, flexible bands of shield-like body armor similar to those of armadillos (Armadillosuchus), and possibly fleshy cheeks and pig-like snouts (Notosuchus). The suborder was first named in 1971 by Zulma Gasparini and has since undergone many phylogenetic revisions.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".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.Sebecosuchia
Sebecosuchia is an extinct group of mesoeucrocodylian crocodyliforms that includes the families Sebecidae and Baurusuchidae. The group was long thought to have first appeared in the Late Cretaceous with the baurusuchids and become extinct in the Miocene with the last sebecids, but Razanandrongobe pushes the origin of Sebecosuchia to the Middle Jurassic. Fossils have been found primarily from South America but have also been found in Europe, North Africa, Madagascar, and the Indian subcontinent.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.Stratiotosuchus
Stratiotosuchus (from Greek, στρατιώτης (stratiōtēs, "soldier") and σοῦχος (suchos, "crocodile")) is an extinct genus of baurusuchid mesoeucrocodylian from the Adamantina Formation in Brazil. It lived during the Late Cretaceous. The first fossils were found in the 1980s, and the type species Stratiotosuchus maxhechti was named in 2001. A hyperpredator, it and other baurusuchids may have filled niches occupied elsewhere by theropod dinosaurs.Trematochampsidae
Trematochampsidae is an extinct family of mesoeucrocodylian crocodylomorphs. Fossils are present from Madagascar, Morocco, Niger, Argentina, and Brazil (in the case of Caririsuchus, where some specimens have been found in the Romualdo Member of the Santana Formation). Possible trematochampsids have been found from Spain and France, but classification past the family level is indeterminant. The trematochampsids first appeared during the Barremian stage of the Early Cretaceous and became extinct during the late Maastrichtian stage of the Late Cretaceous.Ziphosuchia
Ziphosuchia is a clade of mesoeucrocodylian crocodyliforms that includes notosuchians and sebecosuchia