Xixiasaurus

Xixiasaurus () is a genus of troodontid dinosaur that lived during the Late Cretaceous Period in what is now China. The only known specimen was discovered in Xixia County, Henan Province, in central China, and became the holotype of the new genus and species Xixiasaurus henanensis in 2010. The names refer to the areas of discovery, and can be translated as "Henan Xixia lizard". The specimen consists of an almost complete skull (except for the hindmost portion), part of the lower jaw, and teeth, as well as a partial right forelimb.

Xixiasaurus is estimated to have been long and to have weighed . As a troodontid, it would have been bird-like and lightly built, with grasping hands and an enlarged sickle-shaped claw on the second toe. Its skull was long, with a long, low snout that formed a tapering U-shape when seen from below. The of the forehead was dome-like in side view, which indicates it had an enlarged . It differed from other troodontids in that the front of the of the lower jaw was down-turned. Unlike in most troodontids, the teeth of Xixiasaurus did not have ; instead, their (front and back edges) were smooth and sharp. It was distinct among troodontids in having 22 teeth in each (in other genera the maxillary tooth count was either higher or lower).