Tuesday, August 22, 2023

[Paleontology • 2023] Proadocus hadongensis • The First adocid Turtle (Cryptodira: Pan-Trionychia) in South Korea (Lower Cretaceous) and the early Evolution of the Adocidae


Proadocus hadongensis
 Kim, Lee, Ko, Park, Kim, Lee, Jung & Kong, 2023

 
Abstract
An adocid turtle was collected from the Lower Cretaceous Hasandong Formation, representing the first occurrence of the Adocidae in South Korea. The specimens consist of moderately preserved hard shells (carapace and plastron) with a limb bone (humerus). They turned out to be a new taxon named Proadocus hadongensis, gen. et sp. nov., characterized by combining synapomorphic characters of adocids and primitive characters ancestrally retained from basal pantrionychians. The pattern of marginal scales extension and pygal shape are shared with Sinaspideretes wimani and Basilochelys macrobios, the basal pantrionychian taxa of the Late Jurassic–Early Cretaceous in Southeast Asia. A cladistic analysis places it as the most basal taxon in Adocidae. Such phylogenetic position of Proadocus involves important implications about the origin and early evolution of the Adocidae. First, Proadocus supports the Southeast Asian origin of this family. Secondly, a new paleobiogeographic analysis, including Proadocus in Korea, requests a new interpretation of the adocid diversification and dispersion in East Asia during the Early Cretaceous.



Testudines Batsch, 1788 
Cryptodira Cope, 1868 

Pan-Trionychia Hummel, 1929 
Adocusia Danilov and Parham, 2006 

Adocidae Cope, 1870 

Proadocus hadongensis, gen. et sp. nov.


Do Hyeon Kim, Yuong-Nam Lee, Hyejin Ko, Jin-Young Park, Su-Hwan Kim, Sungjin Lee, Seung-Ho Jung and Dal-Yong Kong. 2023. The First adocid Turtle in South Korea (Lower Cretaceous) and the early Evolution of the Adocidae. Cretaceous Research. 151; 105665. DOI: 10.1016/j.cretres.2023.105665