Volaticotherium

 Volaticotherium antiquum  was an actively mobile ancient gliding insectivorous mammal that lived in what would become Asia during the Jurassic period, around 164 mya. It is the only member of the genus Volaticotherium.

It had a gliding membrane similar to a modern-day flying squirrel. The teeth of Volaticotherium were highly specialized for eating insects, and its limbs were adapted to living in trees. The gliding membrane (patagium) was insulated by a thick covering of fur, and was supported by the limbs as well as the tail. The discovery of Volaticotherium provided the earliest-known record of a gliding mammal (70 million years older than the next oldest example),[1] and provided further evidence of mammalian diversity during the Mesozoic Era.

The phylogenetic analysis conducted by the authors of the description of Volaticotherium antiquum recovered it as the sister taxon of the clade that contained, among other taxa, eutriconodonts, multituberculates, spalacotheriid and tinodontid "symmetrodontans", dryolestids, metatherians (including marsupials) and eutherians (including placental mammals). As the analysis didn't place Volaticotherium within any of the previously known main groups of Mesozoic mammals, the authors of its description erected a separate family Volaticotheriidae and order Volaticotheria for it.[2] However, Zhe-Xi Luo (2007) mentioned that Volaticotherium might actually be a eutriconodont.[3] This was eventually confirmed by the phylogenetic analyses conducted by Leandro C. Gaetano and Guillermo W. Rougier (2011, 2012); these analyses recovered Volaticotherium antiquum as a eutriconodont that belonged to the family Triconodontidae and subfamily Alticonodontinae, and was particularly closely related to the genera Argentoconodon and Ichthyoconodon.[4][5]

The only known fossil of Volaticotherium was recovered from the Daohugou Beds of Ningcheng County, Inner Mongolia, China. The age of the Daohugou Beds is currently uncertain and the subject of debate, but most studies suggest an age of around 164 plus or minus 4 million years ago.[6] The description was published in an issue of the journal Nature.