Relatively low tooth replacement rate in a sauropod dinosaur from the Early Cretaceous Ruyang Basin of central China

Huali Chang; Hai-Lu You; Li Xu; Waisum Ma; Diansong Gao; Songhai Jia; Mengli Xia; Jiming Zhang; Yu Li; Xirui Wang; Di Liu; Jie Li; Jianhua Zhang; Lili Yang; Xuefang Wei

doi:10.7717/peerj.12361

Relatively low tooth replacement rate in a sauropod dinosaur from the Early Cretaceous Ruyang Basin of central China

PeerJ. 2021 Oct 27:9:e12361. doi: 10.7717/peerj.12361. eCollection 2021.

Authors

Huali Chang¹, Hai-Lu You^{2

3

4}, Li Xu¹, Waisum Ma⁵, Diansong Gao¹, Songhai Jia¹, Mengli Xia¹, Jiming Zhang¹, Yu Li¹, Xirui Wang¹, Di Liu¹, Jie Li¹, Jianhua Zhang¹, Lili Yang¹, Xuefang Wei⁶

Affiliations

¹ Henan Natural History Museum, Zhengzhou, China.
² Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China.
³ College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China.
⁴ CAS Center for Excellence in Life and Paleoenvironment, Beijing, China.
⁵ School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom.
⁶ Institute of Geology, Chinese Academy of Geological Sciences, Beijing, China.

Abstract

Tooth replacement rate is an important feature related to feeding mechanics and food choices for dinosaurs. However, only a few data points are available for sauropod dinosaurs, partially due to rarity of relevant fossil material. Four somphospondylan sauropod species have been recovered from the Lower Cretaceous Aptian-Albian Haoling Formation in the Ruyang Basin, Henan Province of central China, but no cranial material has been reported except for a single crown. Here we report the discovery of the rostral portion of a left dentary with replacement teeth in its first five alveoli. Comparative anatomical study shows the partial dentary can be assigned to a member of early diverging somphospondylans. The non-destructive tooth length-based approach to estimating tooth formation time and replacement rate is adopted here. The estimated tooth replacement rate is 76 days, faster than that of Brachiosaurus (83 days) and much lower than typical late diverging lithostrotian titanosaurians (20 days). Thus, this discovery adds an intermediate tooth replacement rate in the evolution of titanosauriform sauropods and supports the idea that evolution of tooth replacement rate is clade-specific. This discovery also provides more information to understand the Ruyang sauropod assemblage, which includes one of the most giant dinosaurs to have walked our Earth (Ruyangosaurus giganteus).

Keywords: Early Cretaceous; Henan; Ruyang Basin; Sauropod; Tooth replacement rate.

Grants and funding

This work was supported by the National Natural Science Foundation of China (No. 41688103, 41872021, 41702021), the Strategic Priority Research Program of Chinese Academy of Sciences (No. XDB26000000). Waisum Ma’s participation in this study was supported by UCCL Grant, Universities’ China Committee in London. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.