Tamaulipasaurus morenoi (Clark and Hernandez 1994) Early Jurassic ~165mya, was a burrowing lizard, here derived from a sister to Spathorhynchus and was a sister to the living Bipes. The presence of such a derived lizard in the Early Jurassic indicates that sisters to all the preceding taxa appeared even earlier and diversified during the Triassic.
Distinct from Spathorhynchus, but like Crythiosaurus, the skull of Tamaulipasaurus did not develop a protruding snout. In dorsal view the mid portion of the skull was much narrower with a loss of roofing bones (prefrontal/postfrontal/postorbital) over the orbits. The orbit and jugal extended to the quadrate, greatly reducing the intervening space. The teeth were larger. The quadrate appears to be not supine, angled up more than 60 degrees. What Clark and Hernandez (1994) labeled the quadratojugal is the jugal because preceding taxa did not have a quadratojugal all the way back to the origin of the Lepidosauria.
The anterior mandible was deeper. The posterior of the coronoid process descended gradually.