Leptocleidian Plesiosaur, Rush Creek

Leptocleidian Plesiosaur, North TX

Cenomanian, Cretaceous

Jul, 2023

Between Leptocleididae and Polycotylidae it is unclear which of the two sister families (both within the clade Leptocleidia) this tooth belongs to. This tooth is from marine coastal strata that would have been in near proximity to freshwater sources (see the Woodbine river delta that once existed over Grapevine Lake).

Leptocleididae is known up until the Early Albian from freshwater, near shore, and brackish environments. Some possible teeth were documented from the Kem Kem river system which is similarly aged Cenomanian rock. They typically have very gracile teeth similar to this specimen.

Polycotylidae is a sister taxon that extends through into much younger deposits and is regarded as a marine group. They arose in the Albian and typically have more robust morphologies, though a basal species could be gracile like this specimen.