First record of a mosasaurid (Squamata: Mosasauridae) from the Upper Cretaceous of Ecuador

Abstract

We report the first Upper Cretaceous marine reptile fossil in Ecuador, identified as an incomplete right maxilla from the Mosasauridae family. The remains were unearthed from marine marlstones and limestones within a karstic cave in the Tamia Yura indigenous community, situated northeast of Tena in the central Subandean Zone of the Ecuadorian Amazon. Morphological analysis reveals seven preserved teeth conical in shape. Stratigraphic analysis suggests the remains belong to the Middle Napo Fm, Oriente basin, indicating a presence from the Turonian to the end of the Coniacian. This discovery offers new insights into the study of Cretaceous marine reptiles in South America.