New papers:
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Amabilis uchoensis gen. et sp. nov.Â
Data for this study are available in the Dryad Digital Repository:
https://doi.org/10.5061/dryad.sm61m9s.
http://zoobank.org/References/9DEEDDFB-0188-4CF4-B46C-5E3E9CED0D4F.
Pleurodires are less diverse than cryptodires, together forming the two major lineages of crown turtles. Their fossil record, however, is rich. A particularly large number of fossil pleurodires, many belonging to the Podocnemidoidae, has been recovered from the Upper Cretaceous Bauru Group outcrops of southâcentral Brazil. Herein we describe an additional pleurodire from this region, Amabilis uchoensis gen. et sp. nov., based on a partially preserved skull. A. uchoensis is recognized as belonging to the Podocnemidoidae by the small entrance to the antrum postoticum and completely developed cavum pterygoidei, being unique among other nonâpodocnemidid podocnemidoids for its medially open fenestra postotica and absent basioccipitalâopisthotic contact. Our cladistic analysis places A. uchoensis as a sister taxon to Hamadachelys + other podocnemidoids. We further explore the neuroanatomy of sideânecked turtles with the aid of microâcomputed tomography of specimens of the main pleurodiran lineages. Our data shed light on the different carotid circulation patterns in pleurodires, and we propose new phylogenetic characters to describe the neuroanatomical variation of the group. Optimization of these characters shows two independent acquisitions of a foramen for the palatal branch of the carotid in chelids and podocnemidoids, and a unique loss of the vidian nerve canal in chelids, in turtles in general.
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Lakotemys australodakotensis gen. and sp. nov.
Walter G. Joyce, Yann Rollot, and Richard L. Cifelli (2020)
A new species of baenid turtle from the Early Cretaceous Lakota Formation of South Dakota.
Fossil Record 3: 1-13
doi:
https://doi.org/10.5194/fr-23-1-2020https://www.foss-rec.net/23/1/2020/Baenidae is a clade of paracryptodiran turtles known from the late Early Cretaceous to Eocene of North America. The proposed sister-group relationship of Baenidae to Pleurosternidae, a group of turtles known from sediments dated as early as the Late Jurassic, suggests a ghost lineage that crosses the early Early Cretaceous. We here document a new species of paracryptodiran turtle, Lakotemys australodakotensis gen. and sp. nov., from the Early Cretaceous (Berriasian to Valanginian) Lakota Formation of South Dakota based on a poorly preserved skull and two partial shells. Lakotemys australodakotensis is most readily distinguished from all other named Late Jurassic to Early Cretaceous paracryptodires by having a broad, baenid-like skull with expanded triturating surfaces and a finely textured shell with a large suprapygal I that laterally contacts peripheral X and XI and an irregularly shaped vertebral V that does not lap onto neural VIII and that forms two anterolateral processes that partially separate the vertebral IV from contacting pleural IV. A phylogenetic analysis suggests that Lakotemys australodakotensis is a baenid, thereby partially closing the previously noted gap in the fossil record.
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