Creature of the Week #22: Volaticotherium

marco_polo

Volaticotherium antiquus (rather unimaginatively meaning "ancient gliding beast") was a small, gliding, insectivorous mammal that lived in what is now China during the Jurassic period, at least 125 million years ago. Discovered in the Daohugou Beds of Inner Mongolia, China and described for the first time in 2006, it is the earliest known example of gliding flight by mammals, and demonstrates that mammals were experimenting with aerial life at about the same time as birds first took to the skies. The discovery extended by at least 70 million years the earliest record of known aerial flight for mammals. The previously oldest know example of gliding flight was a 30-million-year old rodent. The oldest record of powered flight is an ancestor of bats dated to approximately 51 million years ago.



Up to a few years ago the majority of scientist held the view that early mammals that lived before 65 million years ago were for the most part simple shrew-like creatures that cowered in the shadows of the dominant dinosaurs. However recent finds like Volaticotherium have turned the tide of scientific opinion, showing that mammals had begun to invade diverse ecological niches long before the extinction of dinosaurs. Although comparable in size and shape to flying squirrel, researchers established from analysis of the fossil that the glider was completely unrelated to any modern mammals. This resulted in an extremely rare event in palaeontology, the designation of an entirely new order of mammals to accommodate this discovery and points to the independent origin of flight in this now extinct lineage of mammals.

The remains some uncertainty about the precise dating of the fossil, with test ranging from as recent as 125 million years ago to as ancient as 164 million years old, however an age closer to the earlier date of approximately 150 mya is thought the best fit. The reason for such uncertainty is primarily because as is the case with a number of 'newer' fossil beds in locations such as China, they have simply been less well studied that their counterparts in Europe or America, the geology of which have been subjected to well over a century of detailed scrutiny.



Volaticotherium was discovered with most of the skeleton preserved, as well impressions of both a large fold of skin membrane stretching between the animal's fore and hind limbs and also fur on its body, a distinctive characteristic of mammals. A long, stiff tail served as a stabilizing rudder during gliding flight. At less than a pound in weight, combined with its large airofoil and long tail it was a highly agile glider. Its highly specialized sharp teeth provide solid evidence that Volaticotherium was an insectivore. Study of the limbs show it was also a profecient climber, important features that would have allowed it to forage for food in trees and also give it the ability to obtain the height necessary for successful gliding.


Image of the fossil.

Galvasean

Really makes you wonder what kind of flying mammals might rule the skies today had birds not suvived the extinction at the end of the Cretaceous.