''Smilosuchus'' (meaning "chisel crocodile") 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 ...

leptosuchomorph Leptosuchomorpha is a clade of phytosaurs. It is a node-based taxon defined as the last common ancestor of '' Leptosuchus studeri'' and '' Pseudopalatus pristinus'' and all of its descendants. Phylogeny Below is a cladogram A cladogram (fr ...

parasuchid Parasuchidae is a clade of phytosaurs more derived than ''Diandongosuchus'', a basal phytosaur. It encompasses nearly all phytosaurs, include early ''Parasuchus''-grade forms as well as a more restricted clade of more specialized phytosaurs. This ...

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 ...

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

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 ''Leptosuchus'' is an extinct genus of leptosuchomorph phytosaur with a complex taxonomical history. Fossils have been found from the Dockum Group and lower Chinle Formation outcropping in Texas, New Mexico, and Arizona, USA, and date back to th ...

'' (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

mystriosuchin Mystriosuchini, historically known as Pseudopalatinae, is an extinct tribe (formerly subfamily) of derived phytosaurs in the clade Leptosuchomorpha. As with all other phytosaurs, mystriosuchins lived during Late Triassic. The name is derived from ...

s 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 A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may ...

. 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 deli ...

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, tear ...

are

heterodont In anatomy, a heterodont (from Greek, meaning 'different teeth') is an animal which possesses more than a single tooth morphology. In vertebrates, heterodont pertains to animals where teeth are differentiated into different forms. For example, ...

, 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 co ...

at the anterior of the

mouth In animal anatomy, the mouth, also known as the oral cavity, or in Latin cavum oris, is the opening through which many animals take in food and issue vocal sounds. It is also the cavity lying at the upper end of the alimentary canal, bounded on ...

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 the ...

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 The quadratojugal is a skull bone present in many vertebrates, including ...

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 Kannemeyeriiforme ...

.''

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 d ...

from Stocker (2012):

References

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