A POLYGLYPHANODONTINE LIZARD FROM THE MORENO HILL FORMATION (TURONIAN, UPPER CRETACEOUS), ZUNI BASIN, NEW MEXICO

The Moreno Hill Formation (middle Turonian) in the Zuni Basin of western New Mexico is known for dinosaurs including Zuniceratops, Nothronychus, Jeyawati, and Suskityrannus. An incomplete but articulated polyglyphanodontine lizard skull was recovered from the same site as the paratype of the tyrannosauroid theropod Suskityrannus. Suskityrannus specimens and the polyglyphanodontine lizard skull were recovered atop and marginal to an indurated silcrete of limited extent.The silcrete yields fish,crocodile, and turtle remains; laterally the unit grades to mudstone containing in situ fossil trees, and abundant wood suggesting the unit was formed from a small, possibly ephemeral pond within a forested setting.

The skull appears to be heavily acid-etched; the surfaces of the skull bones are damaged with fragments of unidentifiable bone cemented in the remaining matrix. The left dentary and maxilla are fairly complete, containing fourteen teeth in the dentary and nine teeth in the maxilla. A portion of the left jugal is preserved, but it is badly damaged.

The teeth exhibit a sharp cutting edge similar to other polyglyphanodontines and are transversely wide, suggesting it belongs to the subclade Polyglyphanodontini. With further analysis of the teeth, it could be possible to narrow down if the skull belongs to an existing taxon or a new taxon. The polyglyphanodontines Bicuspidon numerosus and Dicothodon moorensis are known from the somewhat older Mussentuchit Member (Cenomanian), Cedar Mountain Formation, Utah. Dicothodon cifellii has been found in the slightly younger Smoky Hollow Member (late Turonian), Straight Cliffs Formation, Utah. The heavy acid etching on the skull suggests it had been digested by either a theropod dinosaur or crocodylomorph, though further analysis is needed to explore this possibility.