A new xinjiangchelyid turtle from the Middle Jurassic of Xinjiang, China and the evolution of the basipterygoid process in Mesozoic turtlesReport as inadecuate




A new xinjiangchelyid turtle from the Middle Jurassic of Xinjiang, China and the evolution of the basipterygoid process in Mesozoic turtles - Download this document for free, or read online. Document in PDF available to download.

BMC Evolutionary Biology

, 13:203

Evolutionary developmental biology and morphology

Abstract

BackgroundMost turtles from the Middle and Late Jurassic of Asia are referred to the newly defined clade Xinjiangchelyidae, a group of mostly shell-based, generalized, small to mid-sized aquatic froms that are widely considered to represent the stem lineage of Cryptodira. Xinjiangchelyids provide us with great insights into the plesiomorphic anatomy of crown-cryptodires, the most diverse group of living turtles, and they are particularly relevant for understanding the origin and early divergence of the primary clades of extant turtles.

ResultsExceptionally complete new xinjiangchelyid material from the ?Qigu Formation of the Turpan Basin Xinjiang Autonomous Province, China provides new insights into the anatomy of this group and is assigned to Xinjiangchelys wusu n. sp. A phylogenetic analysis places Xinjiangchelys wusu n. sp. in a monophyletic polytomy with other xinjiangchelyids, including Xinjiangchelys junggarensis, X. radiplicatoides, X. levensis and X. latiens. However, the analysis supports the unorthodox, though tentative placement of xinjiangchelyids and sinemydids outside of crown-group Testudines. A particularly interesting new observation is that the skull of this xinjiangchelyid retains such primitive features as a reduced interpterygoid vacuity and basipterygoid processes.

ConclusionsThe homology of basipterygoid processes is confidently demonstrated based on a comprehensive review of the basicranial anatomy of Mesozoic turtles and a new nomenclatural system is introduced for the carotid canal system of turtles. The loss of the basipterygoid process and the bony enclosure of the carotid circulation system occurred a number of times independently during turtle evolution suggesting that the reinforcement of the basicranial region was essential for developing a rigid skull, thus paralleling the evolution of other amniote groups with massive skulls.

AbbreviationsAMAustralian Museum, Sydney, Australia

CCMCarter County Museum, Montana USA

FMNHField Museum of Natural History, Chicago, USA

IVPPInstitute of Vertebrate Paleontology and Paleoanthropology, Beijing, China

IWCMSDinosaur Isle Museum, see MIWG

MACNMuseo Argentino de Ciencias Naturales -Bernardino Rivadavia-, Buenos Aires, Argentina

MCCMMuseo de las Ciencias de Castilla–La Mancha, Cuenca, Spain

MCZMuseum of Comparative Zoology, Harvard University, Cambridge, USA

MDSirindhorn Museum, Phu Kum Khao, Sahatsakhan, Kalasin Province, Thailand

MHNaturhistorisches Museum, Basel, Switzerland

MIWGMuseum of Isle of Wight Geology, Sandown, United Kingdom

MNAMuseum of Northern Arizona, Flagstaff, USA

MOZPMuseo -Prof. Dr. Juan A. Olsacher-, Zapala, Argentina

MPEFMuseo Paleontológico Egidio Feruglio, Trelew, Argentina

MRFMarmarth Research Foundation, Marmarth, North Dakota, USA

NHMUKNatural History Museum of London, United Kingdom

PINPaleontological Institute, Russian Academy of Sciences, Moscow, Russia

PMOLPaleontological Museum of Liaoning, Shenyang Normal University, Shenyang, China

SAMSouth Australian Museum, Adelaide, Australia

SGPSino-German Cooperation Project

SMNSStaatliches Museum für Naturkunde, Stuttgart, Germany

UMZCUniversity Museum of Zoology, Cambridge, United Kingdom

TMTeylers Museum, Haarlem, The Netherlands

TMPRoyal Tyrrell Museum of Palaeontology, Drumheller, Canada.

Electronic supplementary materialThe online version of this article doi:10.1186-1471-2148-13-203 contains supplementary material, which is available to authorized users.

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Author: Márton Rabi - Chang-Fu Zhou - Oliver Wings - Sun Ge - Walter G Joyce

Source: https://link.springer.com/







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