''Angistorhinus'' (meaning "narrow snout" or "hook snout") is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

phytosaur Phytosaurs (Φυτόσαυροι in greek) are an extinct group of large, mostly semiaquatic Late Triassic archosauriform reptiles. Phytosaurs belong to the order Phytosauria. Phytosauria and Phytosauridae are often considered to be equivalent ...

known from the

Late Triassic The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch ...

period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

and

Wyoming Wyoming () is a U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the south ...

, United States. It was first named by Mehl in

1913 Events January * January 5 – First Balkan War: Battle of Lemnos (1913), Battle of Lemnos – Greek admiral Pavlos Kountouriotis forces the Turkish fleet to retreat to its base within the Dardanelles, from which it will not ven ...

and the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

is ''Angistorhinus grandis''. Other species from Texas and Wyoming, ''A. alticephalus'' (Stovall and Wharton, 1936), ''A. gracilis'' (Mehl, 1915) and ''A. maximus'' (Mehl, 1928), are cospecific with the type species. ''Angistorhinus'' is known from the holotype UC 631, partial

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...

and lower

jaw The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term ''jaws'' is also broadly applied to the whole of the structures constituting the vault of the mouth and serv ...

s recovered from the

Popo Agie Formation The Popo Agie Formation is a Triassic geologic formation that crops out in western Wyoming, western Colorado, and Utah. It was deposited during the Late Triassic in fluvial (river) and lacustrine (lake) environments that existed across much of ...

Chugwater Group Chugwater is a town in Platte County, Wyoming, United States. As of the 2020 census, the town population was 175. History The Chugwater area, with its proximity to Fort Laramie, was visited by some of the earliest Western expeditions, includin ...

and from the associated paratype UM 531, a partial skull, TMM 31098-1, skull and lower jaws and ROM 7977, partial skull and lower jaws, recovered from the 'Pre-Tecovas Horizon' in the

Dockum Group The Dockum is a Late Triassic (approximately late Carnian through Rhaetian, or 223–200 Ma) geologic group found primarily on the Llano Estacado of western Texas and eastern New Mexico with minor exposures in southwestern Kansas, eastern Color ...

. A possible second species, ''A. talainti'' is known from the

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...

Morocco Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to ...

. In 1995, Long and Murry created the new combination, ''Angistorhinus megalodon'' by synonymy for ''

Brachysuchus ''Brachysuchus'' (meaning "wide crocodile") is an extinct genus of phytosaur known from the late Triassic period (Carnian stage) of Dockum Group in Texas, United States. It is known from the holotype UMMP 10336 is composed of a skull, lower jaws ...

''. Hungerbühler and Sues (2001) hypothesised that ''Angistorhinus'' is a junior synonym of ''

Rutiodon ''Rutiodon'' ("Wrinkle tooth") is an extinct genus of phytosaur belonging to the family Parasuchidae. It lived during the Late Triassic period, and was about in length. ''Rutiodon'' is known from the eastern United States (North Carolina, New J ...

''. However, in 2010 Michelle R. Stocker retained the validity of ''

'' and of ''A. grandis''.

Description

''Angistorhinus'' was another of the early phytosaur genera. It was similar to ''

Parasuchus ''Parasuchus'' is an extinct genus of basal phytosaur known from the Late Triassic (late Carnian to early Norian stage) of Andhra Pradesh and Madhya Pradesh, India. At its most restricted definition, ''Parasuchus'' contains a single species, ' ...

'' but differed in having the nostrils located further back, towards and above the eyes. This was a more specialized condition that characterized all late phytosaurs. ''Angisthorhinus'' was a huge animal by any standards; the skull length was generally about 120 cm; estimated overall length to 8 meters, more in ''A. megalodon'', a very large, short and heavy-muzzled form sometimes given its own genus (''

''), and which far exceeded in size any living crocodile.

References

{{Taxonbar, from=Q2287966 Phytosaurs Prehistoric reptile genera Late Triassic reptiles of North America Fossil taxa described in 1913 Taxa named by Maurice Mehl