''Smilosuchus'' (meaning "chisel crocodile") is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of leptosuchomorph parasuchid from the

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

of North America.

History

The type species was first described in 1995 as a replacement generic name for ''Leptosuchus gregorii''. Because of the large rostral crest it possessed, it was considered to be distinct enough from other species of '' Leptosuchus'' (all of which had smaller and more restricted crests) to be within its own genus. Some studies seem to suggest that ''Smilosuchus'' is congeneric with ''Leptosuchus'', as the enlarged crest could have been independently developed in ''Leptosuchus''. However, newer studies support the idea that ''Smilosuchus'' is distinct from the type species of ''Leptosuchus'', ''Leptosuchus crosbiensis''. Phylogenetic analyses suggest that ''Smilosuchus'' is more closely related to mystriosuchins than to ''Leptosuchus'' species.

Description

Smilosuchus-reconstructions-Jeff-Martz-600-px-tiny-Oct-2014-Tetrapod-Zoology

Like all phytosaurs, ''Smilosuchus'' had the

nostrils A nostril (or naris , plural ''nares'' ) is either of the two orifices of the nose. They enable the entry and exit of air and other gasses through the nasal cavities. In birds and mammals, they contain branched bones or cartilages called turbi ...

close to the top of its head. The

rostra The rostra ( it, Rostri, links=no) was a large platform built in the city of Rome that stood during the republican and imperial periods. Speakers would stand on the rostra and face the north side of the comitium towards the senate house and de ...

l crest and nasal bulge supporting these raised nostrils was larger in ''Smilosuchus'' than in many other phytosaurs. Its skull was extremely large, up to 155 cm long, although estimates for the overall length vary from to . The

jaws Jaws or Jaw may refer to: Anatomy * Jaw, an opposable articulated structure at the entrance of the mouth ** Mandible, the lower jaw Arts, entertainment, and media * Jaws (James Bond), a character in ''The Spy Who Loved Me'' and ''Moonraker'' * ...

are very short and broad and the

teeth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, t ...

are heterodont, with large

tusks Tusks are elongated, continuously growing front teeth that protrude well beyond the mouth of certain mammal species. They are most commonly canine teeth, as with pigs and walruses, or, in the case of elephants, elongated incisors. Tusks share ...

at the anterior of the mouth for impaling

prey Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...

and more blade-like teeth for slicing flesh closer to the back of the mouth. The tusks are mounted on a bulge at the tip of the snout present in nearly all phytosaurs. Its

squamosal The squamosal is a skull bone found in most reptiles, amphibians, and birds. In fishes, it is also called the pterotic bone. In most tetrapods, the squamosal and quadratojugal bones form the cheek series of the skull. The bone forms an ancestral co ...

processes are short and deep, indicating a powerful bite. This coupled with its large size (it is one of the largest known phytosaurs) suggests that it hunted large prey such as ''

Placerias ''Placerias'' (meaning 'broad body') is an extinct genus of dicynodonts that lived during the Carnian to the Norian age of the Triassic Period (230–220 million years ago). ''Placerias'' belongs to a group of dicynodonts called Kannemeyeriifor ...

.''

Phylogeny

Below is a

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

from Stocker (2012):

References

Phytosaurs Prehistoric reptile genera Late Triassic reptiles of North America Fossil taxa described in 1995 {{triassic-reptile-stub