Microraptor Skeletons

Microraptor is one of the more curious animals to come from Liaoning Province in China in the last decade, and is currently one of the smallest known fossil dinosaurs. New fossil finds of similar animals have sported long feathers on the arms, legs, and tail. Here, I illustrate (using pencil then digitizing and modifying with PhotoShop) the skeletons of the species, Microraptor zhaoianus, based on three specimens, and the referred species, M. gui, based on more specimens, though so far only the holotype has been illustrated. The smaller one is the holotype of M. zhaoianus, IVPP V12330, and as it is clear it is less complete than the larger specimens, though it preserves more of the skull (tentatively reconstructed). The larger specimens are based on two nearly identical skeletons with CAGS 20-8-001 slightly larger than CAGS 20-7-004, both referred by Hwang and others to M. zhaoianus. The largest specimen is the holotype of M. gui, IVPP V13352.

Examining these skeletal drawings, it is clear that the holotype has slightly shorter legs than the larger specimens, but also has a much smaller ischium. The larger specimens appear as if they are distinctly adapted with their long legs, and the longer leg bones of the larger specimens are relatively longer compared to the femur than the smaller specimen. This suggests that when the animals grew, they became more inclined to running, or perhaps the lower leg (as in the related species Microraptor gui) were encapsulated in large wings (there are hints of large wings on the feet of the holotype, smaller specimen), and so perhaps the longer legs were used for making longer hindwings?