parareptile

Parareptilia is a clade of extinct early sauropsid reptiles that diverged from other reptile lineages early in amniote evolution. They are traditionally viewed as a distinct, basal lineage outside the group that includes most living reptiles (often called Eureptilia). The name implies that parareptiles are “beside” or outside the crown-reptile lineage. The fossil record for parareptiles spans from the Late Carboniferous through the Permian, with their greatest diversity in the Permian; they largely disappear by the end of the Permian, though a few lineages may extend into the early Triassic.

Parareptiles show a range of body plans and ecologies. Mesosaurids were among the earliest and were aquatic, with elongated bodies and paddle-like limbs. Pareiasaurids were large, stocky herbivores, frequently bearing heavy skulls and sometimes dermal armor. Procolophonids were small to medium-sized and often had beak-like mouths with cheek teeth adapted to herbivory or omnivory. A common feature in many parareptile skulls is a reduced or absent temporal opening, giving a broad, robust cranium in several lineages, though there was variation among groups.

Taxonomic and evolutionary significance remains a topic of debate. The precise relationships between parareptiles and other sauropsids, including turtles, have been contested; some hypotheses have linked turtles to parareptiles, while others place turtles within or near diapsid lineages. The parareptile fossil record is global, with notable remains from Europe, Africa, North America, and Asia, illustrating an early and widespread diversification of reptile-like amniotes before the later dominance of other reptile groups.