Xixiasaurus

Xixiasaurus Temporal range: Late Cretaceous, 86 Ma PreЄ Є O S D C P T J K Pg N ↓
Skull
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Dinosauria
Order:	Saurischia
Suborder:	Theropoda
Family:	†Troodontidae
Genus:	†Xixiasaurus Lü et al., 2010
Species:	†X. henanensis
Binomial name
Xixiasaurus henanensis Lü et al., 2010

Xixiasaurus is a genus of extinct troodontid dinosaur from the Late Cretaceous of modern-day China. It was first described as a new taxon in 2010. The type species is X. henanensis. Fossils of Xixiasaurus were discovered in central China, in the Majiacun Formation of Henan, and are believed to have been from the Late Cretaceous (Santonian-Coniacian age, about 86 million years ago). The fossils were described by a team of Chinese scientists composed of a group from the Chinese Academy of Geological Sciences in Beijing and a second group from the Henan Geological Museum in Henan. They chose the name Xixiasaurus henanensis, translating as "Henan Xixia lizard".

Xixiasaurus is a troodontid, a group of small, bird-like, maniraptorans. All troodontids have many unique features of the skull, such as closely spaced teeth in the lower jaw, and large numbers of teeth. Troodontids have sickle-claws and raptorial hands, and some of the highest non-avian encephalization quotients, meaning they were behaviourally advanced and had keen senses.Xixiasaurus is about 1.2 m (3.9 ft) long. It is one of few troodontids that have no serrations on its teeth, similar to its closest relative Byronosaurus. Xixiasaurus has fewer teeth than Byronosaurus and Mei, but more than Sinornithoides, Zanabazar and Saurornithoides. Like Bryonosaurus, the palate is extensive, and the teeth are heterodont.