First sea turtle remains (Pan-Chelonioidea) from the Eocene of Algarrobo, central Chile

Abstract

Two isolated bones of sea turtles from Algarrobo, in central Chile, are described. A fragment of a flat element of Ypresian age is identified as part of a right hypoplastron, referable to an indeterminate Pan-Chelonioidea. A second, large fragment from middle-to-upper Eocene levels belonging to the second or fourth left costal of a carapace, preserves distinctive features such as a considerable uniform thickness (5-7 mm), and a prominent ventral rib ridge, plus scute sulci remarkably similar to extant Cheloniidae such as Chelonia mydas or Lepidochelys spp. Based on these features, it is identified as an indeterminate Pan-Cheloniidae. The studied material represents the first occurrences of sea turtles in the Eocene of central Chile. The different ages of the specimens show the persistence of taxa related to Pan-Chelonioidea throughout the Eocene in the southeastern Pacific, helping to fill the austral geographic gap of the group during the Paleogene.