Reproduction of a fossil rhinoceros from 18 mya and origin of litter size in perissodactyls

Xiao-Kang Lu; Tao Deng; Paul Rummy; Xiao-Ting Zheng; Yuan-Tao Zhang

doi:10.1016/j.isci.2023.107800

Reproduction of a fossil rhinoceros from 18 mya and origin of litter size in perissodactyls

iScience. 2023 Sep 1;26(10):107800. doi: 10.1016/j.isci.2023.107800. eCollection 2023 Oct 20.

Authors

Xiao-Kang Lu^{1

2}, Tao Deng^{3

4}, Paul Rummy³, Xiao-Ting Zheng⁵, Yuan-Tao Zhang⁶

Affiliations

¹ Department of Human Anatomy, Henan University of Chinese Medicine, Zhengzhou, Henan 450046, China.
² State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210000, China.
³ Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China.
⁴ University of Chinese Academy of Sciences, Beijing 100049, China.
⁵ Tianyu Museum of Natural History, Pingyi, Shandong 273300, China.
⁶ Shanwang National Geopark of China, Linqu, Shandong 262600, China.

Abstract

Reproductive strategy is among the most important characteristics of organism. Here, we report reproductive strategy of singleton pregnancy of a fossil rhinoceros, Plesiaceratherium gracile, from 18 mya of the Shanwang Basin, China. Dental and body development data revealed that after birth, the calf of P. gracile is breastfed for 2-3 years; at approximately 5 years of age, when the M2 tooth is slightly worn, the female has already reached sexual maturity and attained a size close to that of an adult and could give birth to the first calf. Furthermore, given litter size is phylogenetically conservative and closely correlates with body size, we conclude that the litter size of perissodactyls is determined by the singleton pregnancy since the Eocene. By contrast, other reproductive traits are highly variable and have a different pace of evolution, and traits observed in living rhinoceroses have been evolving at least since 18 mya.

Keywords: Evolutionary biology; Evolutionary history; Wildlife reproduction.