Acynodon is an extinct genus of alligatoroid crocodilian. When first described it was placed within the family Alligatoridae, but has since been reclassified as a globidontan. It is the oldest and most primitive globidontan known to date, with fossils being found from France, Spain, Italy, and Slovenia. Acynodon first appeared during the early Campanian stage of the Late Cretaceous and became extinct during the Cretaceous–Paleogene extinction event at the Cretaceous–Paleogene boundary. The skull of Acynodon is extremely brevirostrine; it had a very short and broad snout compared to other known alligatorids. Its dentition was quite derived, with enlarged molariform teeth and a lack of maxillary and dentary caniniform teeth, presumably an adaptation to feed on slow prey with hard shells. The paravertebral osteoderms of Acynodon were distinctively double-keeled.
|Skull of Acynodon iberoccitanus (ACAP-FXl)|
Buscalioni et al., 1997
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.Alligatorium
Alligatorium is an extinct genus of atoposaurid crocodylomorph from Late Jurassic marine deposits in France.Amphicotylus
Amphicotylus is an extinct genus of goniopholidid mesoeucrocodylian from the Tithonian of Colorado and Oklahoma.Anthracosuchus
Anthracosuchus (meaning "coal crocodile" in Greek) is an extinct genus of dyrosaurid crocodyliform from the Paleocene of Colombia. Remains of Anthracosuchus balrogus, the only known species, come from the Cerrejón Formation in the Cerrejón mine, and include four fossil specimens with partial skulls. Anthracosuchus differs from other dyrosaurids in having an extremely short (brevirostrine) snout, widely spaced eye sockets with bony protuberances around them, and osteoderms that are smooth and thick. It is one of the most basal dyrosaurids along with Chenanisuchus and Cerrejonisuchus. The species name is a reference to the Balrog, a creature in J. R. R. Tolkien's fantasy novel The Lord of the Rings that could, like the remains of Anthracosuchus, be found in a mine.Atoposauridae
Atoposauridae is a family of crocodile-line archosaurs belonging to Neosuchia. The majority of the family are known from Late Jurassic to Early Cretaceous marine deposits in France, Portugal, and Bavaria in southern Germany. The discovery of the genus Aprosuchus, however, extends the duration of the lineage to the end of the Cretaceous in Romania.Brillanceausuchus
Brillanceausuchus is an extinct genus of atoposaurid crocodylomorph. Fossils have been found in Early Cretaceous–age rocks of Cameroon. The genus is notable for the position of the secondary choana within its palate. Parts of the pterygoid bones make up the rostral margin of the choana and thus separate it from the palatines, a feature also seen in the more advanced neosuchian suborder Eusuchia. This characteristic was once thought to be characteristic of Eusuchia, but its presence in Brillanceausuchus suggests that the trait is homoplasic, thus making the evolution of the position of the choana within crocodilians more complex than previously thought.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.Globidonta
Globidonta is a clade of alligatoroids that includes alligators, caimans, and closely related extinct forms. It is defined as a stem-based clade including Alligator mississippiensis (the American Alligator) and all forms more closely related to it than to Diplocynodon. The group's fossil range extends back into the Late Cretaceous with early alligatoroids such as Albertochampsa and Brachychampsa. Extinct globidontans were particularly common in North America and Eurasia, and their modern range also includes South America. The oldest known globidontan is Acynodon from France, which is also the most basal.Basal globidontans are characterized by their blunt snouts and bulbous teeth. Modern globidontans have flattened snouts and more conical teeth, and are seen as more generalized than earlier globidontans. Generalized forms are usually expected to be ancestral to more specialized forms rather than descendants of them, so it is unusual for basal members of the group to appear specialized. This seems to conflict with the "Law of the Unspecialized" first proposed by Edward Drinker Cope in 1894. Under the Law of the Unspecialized, morphological change is always directed toward specialization, and specialized forms can never become "unspecialized" again. This pattern of change, while not seen in globidontans, can be observed in basal members of Alligatoroidea and Crocodyloidea.
Flat-snouted globidontans occurred two times in the evolution of the clade: once in caimans and once in alligators. Alligator sinensis, the Chinese Alligator, has a snout that is somewhat blunt and could be considered specialized. However, its snout is not nearly as blunt as those of more basal globidontans such as Albertachampsa.If the last common ancestor of Diplocynodon and globidontans was more like Diplocynodon, it would have had a generalized snout shape. It is also possible that the generalized form of Diplocynodon may also have arisen from a specialized blunt-snouted ancestor. Baryphracta, a diplocynodontine closely related to Diplocynondon, has a blunt snout and may have been similar in appearance to such an ancestor.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.Laganosuchus
Laganosuchus is an extinct genus of stomatosuchid crocodyliform. Fossils have been found from Niger and Morocco and date back to the Upper Cretaceous.Laño
Laño (Basque: Lañu) is a hamlet and concejo (a small administrative subdivision) in Condado de Treviño within the Treviño enclave; which is administratively part of the Spanish province of Burgos, but which is completely surrounded by the territory of the Basque country province of Álava. It is best known for the fossils of extinct vertebrates dating from around 70 million years before present which have been found there.Nannosuchus
Nannosuchus (meaning "dwarf crocodile") is an extinct genus of goniopholidid mesoeucrocodylian from the Berriasian of England.Sabresuchus
Sabresuchus is an extinct genus of neosuchian crocodyliform from the Cretaceous of Europe. The name is derived from 'Sabre' in reference to the enlarged and curved fifth maxillary tooth, and 'suchus' from the Ancient Greek for crocodile.Shamosuchus
Shamosuchus is an extinct genus of neosuchian crocodile that lived during the Late Cretaceous (Santonian-Campanian) period in what is now the Gobi desert of Mongolia, approximately 85 to 74 million years ago.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.
Extinct crocodilian species