Petrolacosaurus, the Oldest Known Diapsid Reptile

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Science  03 Jun 1977:
Vol. 196, Issue 4294, pp. 1091-1093
DOI: 10.1126/science.196.4294.1091


Petrolacosaurus, an Upper Pennsylvanian reptile, presents a combination of features that place it within a distinct family of the Eosuchia while also evidencing strong relationships to the ancestral reptiles. It is therefore the earliest and most primitive representative of the largest assemblage of fossil and living reptiles, collectively called diapsids.