Opisthias
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| Opisthias Temporal range: Possible Berriasian record | |
|---|---|
 | |
| Jaw of Opisthias rarus | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Rhynchocephalia |
| Suborder: | Sphenodontia |
| Infraorder: | Eusphenodontia |
| Clade: | Neosphenodontia |
| Clade: | †Opisthodontia |
| Genus: | †Opisthias Gilmore 1909 |
| Type species | |
| Opisthias rarus Gilmore, 1905[1] | |
Opisthias is a genus of sphenodont reptile. The type species, Opisthias rarus, is known from the Late Jurassic (Kimmeridgian-Tithonian) of western North America.[2][3]
Opisthias is primarily known from remains found in the Late Jurassic of the United States, with remains found in the Morrison Formation (Colorado, Utah, and Wyoming),[2][3][1] present in stratigraphic zones 2 and 4–6.[4] Other remains suggested to be closely related to Opisthias are also known from the Late Jurassic Alcobaça Formation of Portugal.[5][6] An undescribed crushed skull (DINO 16454) from the Morrison Formation has been attributed to this genus by some sources, though this has been strongly disputed by others.[7]
A lower jaw is also known from the Berriasian aged Lulworth Formation of the United Kingdom, which appears to be distinct from the type North American species.[8] A fragmentary dentary possibly attributable to Opisthias is also known from the Berriasian aged Angeac-Charente bonebed in France.[9]
