Unusual even among early birds and feathered dinosaurs, "Microraptor" is one of the few known bird precursors to sport long flight feathers on its feet as well as its forearms and hands. This led Xu Xing to describe it as a "four winged dinosaur", and to speculate that it may have glided using all four limbs for lift. Their bodies had a thick covering of feathers. A diamond-shaped fan on the end of the tail gave stability during flight. 