FIRST OCCURRENCE OF THE TEIID LIZARD PENETEIUS FROM THE LATEST CRETACEOUS NAASHOIBITO MEMBER, KIRTLAND FORMATION, SAN JUAN BASIN, NEW MEXICO

Abstract

Three Teeth from the Naashoibito Member, Kirtland Formation can be referred to the unusual teiid lizard Peneteius . Specimens NMMNH P-36544, P-41223, and P-41224 were recovered by screen washing from NMMNH locality 4005. The locality 4005 has also yielded isolated teeth mammals including the Lancian index taxon Essonodon browni , dinosaurs, crocodilians, and other squamates. P-41223 represents an isolated lower tooth, P-36544 and P-41224 are upper teeth. Isolated osteoderms (P-36543) from locality 4005 may also belong to the same taxon. The Naashoibito Member Peneteius teeth closely resemble the teeth of P. aquilonius , from the late Maastrichtian Hell Creek Formation of Montana. Peneteius is also known from the late Maastrichtian of Montana and the Campanian of Utah and Texas. Peneteius has teeth with a more complicated structure than is known for any other lizard. They are convergent on the molariform cheek teeth of mammals. It was a relatively small lizard with an estimated snout to vent length of about 80 mm and may have had an insectivorous diet. Its mammal-like teeth may have allowed it to orally process food more efficiently than other lizards.