Simosaurus gaillardoti was a marine reptile that lived in shallow tropical seas covering much of what is now Europe and the Middle East, about 242-235 million years ago.
It was part of the nothosaurian lineage, a group of semi-aquatic sauropterygians that were widespread throughout the Triassic seas before the rise of the more fully marine plesiosaurs.
Growing up to around 4m long (~13'), Simosaurus had a flat short-snouted skull and rather thick blunted teeth, along with jaw musculature adapted for a quick strong snapping bite — suggesting it specialized in crushing tough prey like shelled cephalopods and hard-scaled fish.
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References:
Cabezuelo-Hernández, Alberto, Carlos de Miguel Chaves, and Adán Pérez-García. "The oldest simosaurids (Anisian of Israel): implications for the paleobiogeographic and stratigraphic distributions of the group: A. Cabezuelo-Hernández et al." PalZ (2026): 1-34. https://doi.org/10.1007/s12542-025-00769-2
Dalla Vecchia, Fabio. "First record of Simosaurus (Sauropterygia, Nothosauroidea) from the Carnian (Late Triassic) of Italy." Rivista Italiana di Paleontologia e Stratigrafia 114.2 (2008): 273-285. https://doi.org/10.13130/2039-4942/5902
London, Elisa H., et al. "The braincase anatomy of Simosaurus gaillardoti (Diapsida: Sauropterygia) revealed with X-ray micro-computed tomography." PeerJ 13 (2025): e19932. https://doi.org/10.7717/peerj.19932
Wikipedia contributors. “Simosaurus” Wikipedia, 16 Nov. 2025, https://en.wikipedia.org/wiki/Simosaurus
lijiangosaurus yongshengensis a recently discovered long-necked nothosaur from middle Triassic China.
The image depicting four nothosaur species known from the same area as lijiangosaurus (central and the largest nothosaur in the image); the other nothosaurs are nothosaurus yangjuanensis, n. luopingensis, brevicaudosaurus jiyangshanensis, and lariosaurus hongguoensis
