Smilosuchus gregorii lived in what is now the Southwestern United States during the Late Triassic, about 218 million years ago.
Despite looking a lot like a crocodilian it wasn’t very closely related to modern crocs at all, instead being a phytosaur — a lineage of early pseudosuchians (or possibly earlier-branching archosauriformes) that convergently evolved a crocodile-like lifestyle and appearance.
Around 6m long (~20′), it was armored with bony osteoderms and had long toothy jaws with tusk-like teeth at the tip. But unlike the crocodiles it resembled its nostrils were set high on its snout up near its eyes, and it probably had scaly lizard-like lips.
The high-set position of its nose and a fossil specimen surviving for some time with both of its hind legs compromised by osteomyelitis suggest that Smilosuchus was semi-aquatic. Based on fossil bones of large terrestrial animals like rauisuchids with phytosaur teeth stuck in them it was probably a croc-like ambush predator lunging at prey at the water’s edge — but it may also have been capable of walking around on land with an upright “high walk” gait.
References:
- Drumheller, Stephanie K., Michelle R. Stocker, and Sterling J. Nesbitt. “Direct evidence of trophic interactions among apex predators in the Late Triassic of western North America.” Naturwissenschaften 101.11 (2014): 975-987. https://www.researchgate.net/publication/265733522_Direct_evidence_of_trophic_interactions_among_apex_predators_in_the_Late_Triassic_of_western_North_America
- Heckert, Andrew B., Tabitha C. Viner, and Matthew T. Carrano. “A large, pathological skeleton of Smilosuchus gregorii (Archosauriformes: Phytosauria) from the Upper Triassic of Arizona, USA, with discussion of the paleobiological implications of paleopathology in fossil archosauromorphs.” Palaeontologia Electronica 24.2 (2021): 1-36. https://doi.org/10.26879/1123
- Padian, Kevin, Cheng Li, and Julia Pchelnikova. “The trackmaker of Apatopus (Late Triassic, North America): implications for the evolution of archosaur stance and gait.” Palaeontology 53.1 (2010): 175-189. https://doi.org/10.1111/j.1475-4983.2009.00924.x
- Terras, Rafael, et al. “Inferred presence of extraoral tissues in Triassic archosauromorphs and the evolutionary implications for the clade Sauropsida.” Palaeontology 69.3 (2026): e70066. https://doi.org/10.1111/pala.70066
- Wikipedia contributors. “Smilosuchus” Wikipedia, 10 Aug. 2026, https://en.wikipedia.org/wiki/Smilosuchus