A sinemydid turtle from the Jehol Biota provides insights into the basal divergence of crown turtles

Zhou, Chang-Fu; Rabi, Marton [Rabi, Márton (őslénytan), author] Department of Palaeontology (ELTE / ELU FoS); MTA-ELTE Lendület Dinosaur Research Group (ELTE / ELU FoS)

English Article (Journal Article) Scientific
Published: SCIENTIFIC REPORTS 2045-2322 2045-2322 5 Paper: 16299 2015
  • Szociológiai Tudományos Bizottság: A nemzetközi
  • Regionális Tudományok Bizottsága: B nemzetközi
  • SJR Scopus - Multidisciplinary: D1
Identifiers
Fundings:
  • (95102) Funder: MTA Lendület
Subjects:
  • Other natural sciences
Morphological phylogenies stand in a major conflict with molecular hypotheses regarding the phylogeny of Cryptodira, the most diverse and widely distributed clade of extant turtles. However, molecular hypotheses are often considered a better estimate of phylogeny given that it is more consistent with the stratigraphic and geographic distribution of extinct taxa. That morphology fails to reproduce the molecular topology partly originates from problematic character polarization due to yet another contradiction around the composition of the cryptodiran stem lineage. Extinct sinemydids are one of these problematic clades: they have been either placed among stem-cryptodires, stem-chelonioid sea turtles, or even stem-turtles. A new sinemydid from the Early Cretaceous Jehol Biota (Yixian Formation, Barremian-Early Aptian) of China, Xiaochelys ningchengensis gen. et sp. nov., allows for a reassessment of the phylogenetic position of Sinemydidae. Our analysis indicates that sinemydids mostly share symplesiomorphies with sea turtles and their purported placement outside the crown-group of turtles is an artefact of previous datasets. The best current phylogenetic estimate is therefore that sinemydids are part of the stem lineage of Cryptodira together with an array of other Jurassic to Cretaceous taxa. Our study further emphasises the importance of using molecular scaffolds in global turtle analyses.
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2024-11-07 10:40