A new species of Chrysemys (Emydidae: Deirochelyinae) from the latest Miocene-Early Pliocene of Tennessee, USA and its implications for the evolution of painted turtles.

This article focuses on the discovery and analysis of *Chrysemys corniculata* sp. nov., a new fossil species of painted turtle from the latest Miocene–earliest Pliocene Gray Fossil Site in Tennessee, USA. *Chrysemys corniculata* is identified as a basal member of the subfamily Deirochelyinae within the family Emydidae and exhibits distinctive morphological features, including pronounced anterior projections ("nuchal horns") on the carapace. Phylogenetic analyses suggest that either the genus *Chrysemys* represents one of the oldest and most basal deirochelyine morphologies or that similar basal traits evolved multiple times independently within the group. The coexistence of *C. corniculata* with the extant species *Chrysemys picta* during the Late Hemphillian–Early Blancan North American Land Mammal Age indicates either multiple *Chrysemys* species or multiple basal deirochelyine lineages at that time. The study also discusses the evolutionary history, biogeography, and paleoecology of *Chrysemys*, highlighting its broad native range in North America and its ecological preferences, while emphasizing the importance of climatic shifts in shaping emydid diversification.