A new Early Cretaceous tritylodontid (Synapsida, Cynodontia, Mammaliamorpha) from the Kuwajima Formation (Tetori Group) of central Japan

ABSTRACT

We describe tritylodontid remains from the Lower Cretaceous Kuwajima Formation (Tetori Group) in central Japan as representing a new genus, Montirictus kuwajimaensis, gen. et sp. nov. Montirictus is a medium-sized tritylodontid genus characterized by upper cheek teeth having the cusp formula 2-2-2 with subequal cusps, buccal and lingual cusps retaining a crescentic shape with both buccal and lingual ridges anteriorly, and ‘V’-shaped buccolingual cross-sections of two anteroposterior grooves between the three cusp rows. Tentative dating of the Kuwajima Formation to the Barremian–Aptian makes it the stratigraphically youngest representative of a long-lived, globally distributed and abundant mammaliamorph lineage and extends the known geographic range of tritylodontids.

http://zoobank.org/urn:lsid:zoobank.org:pub:DE3038A4-6C14-4214-9618-BF9F097A4DD4

Citation for this article: Matsuoka, H., N. Kusuhashi, and I. J. Corfe. 2016. A new Early Cretaceous tritylodontid (Synapsida, Cynodontia, Mammaliamorpha) from the Kuwajima Formation (Tetori Group) of central Japan. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1112289.

ACKNOWLEDGMENTS

We would like to express our sincere gratitude to Y. Hasegawa, S. Isaji, I. Yamaguchi, M. Yamaguchi, S. Nakai, all members of the Research Group on the Fossils from the Kuwajima Kaseki-kabe led by M. Manabe, the Ishikawa Prefecture Board of Education, the Hakusan City Board of Education, the former Shiramine Village Board of Education, T. Setoguchi, and T. Tsubamoto for their helpful assistance and support of this study. Specimen observation in Russia was kindly supported by E. N. Maschenko, in the U.K. by S. E. Evans, A. Milner, and D. Unwin, and in China by C.-K. Li, Y.-Q. Wang, G.-H. Cui, and G.-Z. Peng. This paper was greatly improved by numerous significant comments and suggestions by reviewer H.-D. Sues and editor L. Werdelin. This study was partly supported by an Anglo-Japanese joint research grant awarded to M. Manabe and S. E. Evans from The Royal Society/British Council/The Japan Society for the Promotion of Science (JSPS); a Grant-in-Aid for Overseas Scientific Survey (no. 09041161; principal investigator, Nobuo Shigehara) from the Japan Ministry of Education, Science, and Culture; a Grant-in-Aid for Research Promotion from Ehime University, a Grant-in-Aid for Young Scientists (B) (no. 24740349) from JSPS, and Projet International de Coopération Scientifique (DINASIA) from Centre National de la Recherche Scientifique, France, awarded to N.K.; and the Bob Savage Award of the Department of Earth Sciences (University of Bristol), the Sylvester Bradley Award of the Palaeontological Association, the John Ray Trust, the Systematics Research Fund of the Systematics Association and Linnean Society of London, the Doris and Samuel P Welles Fund of the University of California Museum of Paleontology, and the Synthesys fund of Framework 6 of the European Commission awarded to I.J.C.