| Xiaosaurus | |
|---|---|
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | †Ornithischia |
| Clade: | †Neornithischia |
| Genus: | †Xiaosaurus Dong & Tang, 1983 |
| Species: | †X. dashanpensis |
| Binomial name | |
| †Xiaosaurus dashanpensis Dong & Tang, 1983 | |
Xiaosaurus ("dawn lizard",/ʃaʊˈsɔːrəs/), is agenus of smallherbivorousdinosaur from the middleJurassic, approximately 170.3 to 163.5 mya.Xiaosaurus lived in what is now theSichuan Basin ofChina.
In 1979 and 1980, two specimens were discovered of a small herbivorous dinosaur during excavations nearDashanpu inSichuan. In 1983Dong Zhiming andTang Zilu named the fossils under thetype speciesXiaosaurus dashanpensis. The generic name is derived fromChinesexiáo, 曉, "dawn", a reference to the age of the fossil. Thespecific name refers to Danshanpu.[1]
Theholotype,IVPP V6730A, was found in the lowerXiashaximiao Formation of which the age is uncertain: both theBajocian and theBathonian–Callovian have been proposed. It consists of a partial skeleton including a jaw fragment with a single tooth, two cervicalvertebrae, four caudal vertebrae, ahumerus, a partial leftfemur and a complete right hindlimb. Theparatype IVPP V6730B is a second partial skeleton including a right femur, a dorsal vertebra, two sacral vertebrae, aphalanx, a rib and two teeth.
In 1992Peng Guangzhao renamedAgilisaurus multidens He & Cai 1983 (nowHexinlusaurus) into a second species ofXiaosaurus:Xiaosaurus multidens,[2] but this has not been accepted.
Xiaosaurus was a small bipedal animal with an estimated length of one metre. The femur is 11 centimetres (4.3 in) long.
The remains are too fragmentary to easily classify the genus. The describers assigned it both to theFabrosauridae and theHypsilophodontidae, considering it anevolutionary link betweenLesothosaurus andHypsilophodon.Xiaosaurus has sometimes been considered anomen dubium and anornithischianof uncertain affinities, possibly a basalcerapod ormarginocephalian. However,Paul Barrettet al. in 2005 concluded it to be provisionally valid, as it possessed a single unique derived trait orautapomorphy: a mediolaterally (seen from the front) straight humerus.[3]
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