Fossil Record 23(1): 1-13, doi: 10.5194/fr-23-1-2020
A new species of baenid turtle from the Early Cretaceous Lakota Formation of South Dakota
expand article infoWalter Joyce, Yann Rollot, Richard L. Cifelli§
‡ Departement für Geowissenschaften, Universität Freiburg, Freiburg, 1700, Switzerland§ Oklahoma Museum of Natural History, Norman, OK 73072, United States of America
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Baenidae is a clade of paracryptodiran turtles known fromthe late Early Cretaceous to Eocene of North America. The proposedsister-group relationship of Baenidae to Pleurosternidae, a group of turtlesknown from sediments dated as early as the Late Jurassic, suggests a ghostlineage that crosses the early Early Cretaceous. We here document a newspecies of paracryptodiran turtle, Lakotemys australodakotensis gen. and sp. nov., from the EarlyCretaceous (Berriasian to Valanginian) Lakota Formation of South Dakotabased on a poorly preserved skull and two partial shells. Lakotemys australodakotensis is most readilydistinguished from all other named Late Jurassic to Early Cretaceousparacryptodires by having a broad, baenid-like skull with expandedtriturating surfaces and a finely textured shell with a large suprapygal Ithat laterally contacts peripheral X and XI and an irregularly shapedvertebral V that does not lap onto neural VIII and that forms twoanterolateral processes that partially separate the vertebral IV fromcontacting pleural IV. A phylogenetic analysis suggests that Lakotemys australodakotensis is a baenid,thereby partially closing the previously noted gap in the fossil record.