The Aye-aye Dinosaur

Scansoriopteryx was described by Czerkas for an odd specimen originally procurred from fossil dealers at the Tuscon Rock Show, an annual gathering of fossil dealers at Tuscon, Arizona, USA. The fossils likely come from sediments found in the Chinese autonomous district Nei Mongol's Ningcheng County, known as the Daohugou Beds, which might be earliest Cretaceous in age (though Czerkas originally suggested they come from Liaoning Province's Yixian Formation, which is younger in age). As such, the fossil was illegally exported, and Czerkas returned it to China, but not until he had taken the cleanest photos yet of a bizarre group of tiny dinosaurs, Scansoriopterygidae. Their most peculiar feature happens to be the extremely elongated third manual digit or finger, shown here in two views. Notice in the top illustration how difficult it is to hold the arm in a typical "running" posture while keeping the arms vertical and below the body. Thus the bottom illustration shows a possible extended posture. However, the fossils of both known species, the other being Epidendrosaurus ningchengensis also known from Nei Mongol's Daohugou, were apparently very young, as suggested by the poorly defined ends to the limb bones, the huge head, huge eyes compared to head, and gangly-looking legs.