Libognathus (meaning "southwest jaw" in Greek) is an extinct genus of procolophonid parareptile from the Late Triassic of Texas.

The type and only species, Libognathus sheddi, was named in 1997 from the Cooper Canyon Formation in the fossil-rich Post Quarry, which is found in Garza County.

This form of tooth replacement is similar to that in most other reptiles, but different from the condition in most other procolophonids, which have teeth that are fused to the bone of the jaw.

[1] Several procolophonid specimens from the Owl Rock Member of the Chinle Formation in Arizona have been found to be closely related, and possibly referrable to, Libognathus.

Cranial anatomy of Libognathus sheddi Small, 1997 (Parareptilia, Procolophonidae) from the Upper Triassic Dockum Group of West Texas, USA.