Two large squirrels (Rodentia, Mammalia) from the Junggar Basin of northwestern China demonstrate early radiation among squirrels and suggest forested paleoenvironment in the late Eocene of Central Asia

Fossil evidence is indispensable for studying the derivation, divergence, and dispersal of squirrels as they responded to global Cenozoic climatic paleoenvironmental change. Among these fossil records, earliest known definitive in Eurasia occur after Eocene/Oligocene Boundary are slightly younger than oldest records North America. Here, we report discovery two new extinct large squirrel species from late Eocene Junggar Basin northwestern China. The dental morphologies taxa represent tree flying morphotypes, their estimated body masses approximately 1.2 kg 2.6 kg, respectively. In addition, lineages push age first appearance Sciuridae northern Asia into Eocene. Together with Douglassciurus Oligospermophilus America, sciurids, analysis teeth clearly demonstrates that three principle morphotypes sciurids (flying, ground, squirrels) had diverged one another by That proposed divergence among major groupings consistent some molecular clock analyses helps document macroevolutionary timing pattern. Comparison modern analogs over 1 points early Chinese having occupied forested habitats, hypothesis congruent published palynological studies. Furthermore, Jeminay provide data evaluate examination long-term aridification Central Asia.