Haplocheirus


Haplocheirus is a genus of alvarezsauroid theropod dinosaur. It is the oldest known alvarezsauroid, predating all other members by about 63 million years. Haplocheirus was described in 2010 from a fossil specimen found from the 160-million-year-old Shishugou Formation in the Junggar Basin of northwestern China. The type species is H. sollers, meaning "simple-handed skillful one", referencing its hypothesized behavior of using its three-fingered hands for activities that other alvarezsauroids could not perform, such as catching prey.

Description

Haplocheirus was the largest known definite alvarezsauroid, at around 2 meters long. It had an enlarged thumb claw like other alvarezsauroids, but also retained two other functional fingers, unlike more derived alvarezsauroids, where only the thumb was significantly large and clawed. It had long legs and was probably a fast runner.