Box #9 in our count down is Volaticotherium…
Volaticotherium: the “Ancient Gliding Beast”
Volaticotherium lived in Jurassic China, and flies in the face of anyone’s idea of Jurassic mammals only being tiny, shrewish things. This squirrel-like critter doesn’y fly, but is among the earliest known gliding mammals. It was about the size of modern “flying squirrels” at 5-6in (13-15cm) long, and had dense fur, a flat tail for maximum gliding efforts, and of course the membranes of skin between the hands and feet that are so distinctive for anything like a flying squirrel. But that is where the similarities end.
Volaticotherium was a true mammal, but it was more closely related to the egg-laying platypus than to us. Did Volaticotherium lay eggs? No one knows, but we do know a lot about its teeth. Most gliding mammals these days eat fruit, sap, nectar, or are otherwise vegetarian. This prehistoric glider had the sharp teeth and canines of its family group, which means it lived on insects and other creepy crawlies. Imagine a Volaticotherium spying a flying insect in the forest canopy it called home. It bobs its head up, down, and side to side, readies for the pounce, and leaps into the air. The insect sees it coming and tries to dodge, but the mammal sees this and corrects its angle with expert precision, snatches the insect out of the air, and then leisurely glides in for a landing to the nearest tree.
Perhaps a bit less dramatic, it spies an insect perched on a leaf the next tree over. Either way, any clumsiness walking on flat ground is not a problem if a critter can move far quicker and more efficiently simply leaping from tree to tree. Especially when there are so many tasty Jurassic insects like katydids and hanging flies well, hanging around.
Why Jurassic, and not early, middle, or late Jurassic? The Jurassic period, afterall, covers more time than the time between T. rex and humans…It is not exactly certain how old the Haifanggou formation is, which is where the only fossil Volaticotherium is known from. Sometimes layers of rock erode away before the next layer is formed, or layers of rock are folded and warped by the slow movement of Earth’s tectonic plates. Heat from this same geologic activity can mess with chemical forms of dating. This particular area has all those problems. Luckily we can use index fossils, which are any plant or animal fossils that are very common across the globe, but very specific to a certain time. This time there were salamanders (nobody says what kind), and one can propose that the Daohugou Bed was somewhere in the middle to late Jurassic Period.