Dryadissector

Dryadissector (meaning "Dryad dissector" in Greek) is an extinct genus of varanoid lizard represented by the type species Dryadissector shilleri from the Late Cretaceous of Texas.

These teeth are common in early Campanian strata within the Aguja Formation, which date back about 82 to 80 million years.

However, their lizard affinities are made evident by serrations that are smaller and more numerous than those of theropods, as well as a bulge on the inner surface of the base of each tooth that is characteristic of varanoids.

[1] In most Late Cretaceous fossil assemblages where varanoids and theropods coexist (e.g. the Foremost and Oldman formations in Alberta, where the varanoid Palaeosaniwa is found alongside theropods like Saurornitholestes), varanoids are a rare component of the fauna and their teeth are greatly outnumbered by those of theropods.

The lower Aguja may therefore preserve a rare ecosystem in which varanoid lizards outcompeted small theropods as the dominant mesopredators.