New Material of Karakoromys (Ctenodactylidae, Rodentia) from Late Eocene-Early Oligocene of Ulantatal (Nei Mongol): Taxonomy, Diversity, and Response to Climatic Change

The Eocene-Oligocene Transition (EOT) was one of the most profound climate changes in Cenozoic era, characterized by global cooling around 34 million years ago. This time period also witnessed major faunal turnovers, such as “Mongolian Remodeling” Asia, dominance rodents and lagomorphs after EOT. Previous studies have primarily focused on overall change across Here, we examined genus, earliest ctenodactylid Karakoromys, based rich fossils from continuous sections at Ulantatal, Nei Mongol, magnetostragraphically dated to latest Eocene-Early Oligocene. Based a systematic paleontological study these fossils, recognized four species Karakoromys (Karakoromys decussus, K. arcanus, chelkaris, conjunctus sp. nov.), indicating relatively high diversity primitive ctenodactylids during Oligocene (~34.9–30.8 Ma). turnover occurred regional aridification event 31 Ma rather than EOT event, suggesting that precipitation variation semi-arid area may played more important role temperature evolution early ctenodactylids.