Timing of intercontinental faunal migrations: Anguimorph lizards from the earliest Eocene (MP 7) of Dormaal, Belgium

Abstract

Here we report on anguimorph lizards from the earliest Eocene (MP 7) of the Dormaal locality in Belgium, from the time of the warmest global climate of the past 66 million years. Several clades can be identified in this site: Glyptosauridae, Varanidae, and Palaeovaranidae. Our study focuses on glyptosaurid specimens previously reported from the site, some of which had been provisionally described as a new species,?Placosaurus ragei, and some assigned to an unnamed Placosauriops-like ‘melanosaurine’. Our study presents data on new material, including an almost complete glyptosaurine frontal that has enabled us to assign much of the previously described material to a single genus and species. The specimens that had been assigned to both ?P ragei and the ‘melanosaurine’ share apomorphies (flat osteoderms and chevron-shaped osteoderms) with Gaultia, a glyptosaurid previously known from the earliest Eocene of Wyoming, USA. The Dormaal material represents the first record of this genus outside North America. In fact, the only potential evidence of the occurrence of ‘Melanosaurinae’ in Dormaal might be a single isolated vertebra described here. Here we also describe previously unfigured material of Saniwa and palaeovaranids from Dormaal. The presence of previously reported helodermatids cannot be supported in this Belgian site.