Lizards of the Mussentuchit Local Fauna (Albian–Cenomanian boundary) and comments on the evolution of the Cretaceous lizard fauna of North America

Abstract

ABSTRACT A diverse fauna of lizards has been recovered from the Cedar Mountain Formation (Albian–Cenomanian boundary) of central Utah. These lizards are a component of the now recognized Mussentuchit local fauna and, like many of the other vertebrate groups within this fauna, show striking similarities to their North American Late Cretaceous (Campanian–Maastrichtian) counterparts. Unlike the Late Cretaceous lizard faunas, the lizards from the Mussentuchit local fauna also include at least one “paramacellodid,” a group common to Late Jurassic and Early Cretaceous lizard faunas of North America. Comparison with other Cretaceous lizard faunas from both North America and Asia indicates that the changes in the North American lizard fauna represented by the lizards of the Mussentuchit local fauna are likely the result of the introduction of taxa from Asia during the Early Cretaceous. Supposedly herbivorous taxa are found among the Polyglyphanodontine lizards from the Late Cretaceous of North American and Asia, but the general changes in the Cretaceous lizard fauna of North America cannot be convincingly shown to be linked to the concurrent angiosperm radiation. Later influxes of Asian lizard taxa prior to the Campanian may explain the relatively sudden appearance of additional groups of lizards in the early Campanian of North America. Whereas there is good evidence to support the hypothesis of an Asian influence on the Cretaceous lizard fauna of North America, there is insufficient evidence to determine what, if any, influence may have come from Europe or South America.