Name: Smilosuchus ‭(‬Knife crocodile‭)‬.
Phonetic: Smie-loe-soo-kus.
Named By: R.‭ ‬A.‭ ‬Long and P.‭ ‬A.‭ ‬Murray‭ ‬-‭ ‬1995.
Synonyms: Leptosuchus gregorii.
Classification: Chordata,‭ ‬Reptilia,‭ ‬Archosauria,‭ ‬Phytosauria,‭ ‬Phytosauridae.
Species: S.‭ ‬gregorii‭ (‬type), S. adamensis, S. lithodendrorum‬.
Diet: Carnivore.
Size: S. gregorii about 6.7 meters long, S. adamensis about 5 meters long.
Known locations: USA,‭ ‬Arizona.
Time period: Carnian to Norian of the Triassic.
Fossil representation: Several specimens.

       Smilosuchus was originally assigned as a large species of Leptosuchus and was classed as the species Leptosuchus gregorii.‭ ‬A key characteristic of the species was the pronounced nasal crest that supported the nostrils‭ (‬the nostrils in phytosaurs were higher up the snout in front of the eyes,‭ ‬rather than on the end of the snout like those seen in crocodiles‭)‬,‭ ‬and in‭ ‬1995‭ ‬the species was re-evaluated and considered to be distinct enough to separate it into its own genus.‭ ‬Thus the material became known as Smilosuchus gregorii,‭ ‬the gregorii part being taken from the original species classification which is standard procedure when creating a new genus from a previously established species.‭ ‬However since this has happened other palaeontologists have claimed that the fossil material now assigned as Smilosuchus is actually not different enough to treat it as a distinct.‭ ‬As such Smilosuchus faces an uncertain future at the time of writing,‭ ‬but future fossil discoveries may yet prove support for one theory over the other.

How Smilosuchus compares with the giant crocodiles
Name Time/Location Size (meters)
Deinosuchus‭ (‬alligator-like crocodile‭). Cretaceous/USA. 10-12
Gryposuchus‭ (‬gharial-like crocodile‭). Miocene/S.‭ ‬America. 10
Mourasuchus‭ (‬alligator-like crocodile‭). Miocene/Peru. 12
Purussaurus‭ (‬caiman-like crocodile‭). Miocene/S.‭ ‬America. 11-13
Rhamphosuchus‭ (‬gharial-like crocodile‭). Miocene/India‭. 8-11
Sarcosuchus‭ (‬crocodile‭). Cretaceous/Africa. 11-12
Smilosuchus‭ (‬phytosaur *not a croc‭). Triassic/USA. Up to 6.7
Stomatosuchus‭ (‬crocodile‭). Cretaceous/Egypt. 10
3 of todays largest living crocs below
Alligator mississippiensis‭ (‬American alligator‭). Present/S. E. USA. 3.4‭ ‬average‭ ‬- up to almost‭ ‬6.
Crocodylus niloticus‭ (‬Nile crocodile‭). Present/Africa. Average up to‭ ‬5,‭ ‬largest up to 6.45.
Crocodylus porosus‭ (‬Salt water crocodile‭). Present/India, S. E. Asia, N. Australia. Average 4-5.5, largest recorded 6-6.6, possibly slightly bigger.

Further reading
- Late Triassic (Carnian and Norian) tetrapods from the southwestern United States. - New Mexico Museum of Natural History and Science Bulletin 4:1-254. - R. A. Long & P. A. Murry - 1995.
- A new taxon of phytosaur (Archosauria: Pseudosuchia) from the Late Triassic (Norian) Sonsela Member (Chinle Formation) in Arizona, and a critical reevaluation of Leptosuchus Case, 1922. - Palaeontology 53:997-1022. - M. R. Stocker - 2010.


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