New material (Tritylodontidae, Mammaliamorpha) from the lower Jurassic of Lufeng and its implication on the taxonomy of Lufengia

ABSTRACT

The Lufeng locality of China was a major biodiversity hotspot for sauropods and tritylodontids during the Early Jurassic. We describe a partly crushed cranium with complete dentition and dentaries from the Early Jurassic Lufeng Formation of China that we refer to Lufengia. The upper postcanine row length is 10.27 mm, representing one of the smallest tritylodontids to date. Lufengia and Dianzhongia are comparable in the upper postcanine dental pattern in having upper postcanine teeth with the cusp formula 2-3-3 and a small distolingual cusp. Based on the new discovery, Dianzhongia is here considered to be an older individual of Lufengia. Through the micro-computed tomography (micro-CT) of the fossil, differing paths of upper and lower dental replacements alongside new details about tooth replacement in tritylodontids have been revealed.

KEYWORDS:

• Yunnan
• Lufeng formation
• early Jurassic
• tooth replacement
• Tritylodontidae

Acknowledgments

We thank Drs. Jun Liu, Zhaoqun Zhang, Xing Xu (IVPP), James Clark (The George Washington University), and Elsa Panciroli (University of Oxford) for suggestions and comments; Mr. Shuhua Xie (IVPP) for specimen preparation; and Dr. Huijuan Mai for assistance in CT scanning. We appreciate the detailed revision work and suggestions provided by Dr. Simone Hoffmann and an anonymous reviewer, which greatly enhanced the quality of this article. The study was supported by State Key Laboratory of Palaeobiology and Stratigraphy (Nanjing Institute of Geology and Paleontology, CAS) (No. 153110), the Double First-Class joint program of Yunnan Science & Technology Department and Yunnan University (2018FY001-005) and China-Myanmar Joint Laboratory for Ecological and Environmental Conservation.

Disclosure statement

No potential conflict of interest was reported by the authors.

Author Contributions

L. W. J. L and S. B. conceived the study, undertook comparative and analytical work and wrote the paper; B.B and G.Z edited the manuscript; and T. W. and B.B. contributed to fossil interpretation.

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.