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XIAOSAURUS

a plant-eating neornithischian dinosaur from the Middle Jurassic of China.
Pronunciation: shyow-SOR-us
Meaning: Dawn lizard
Author/s: Dong and Tang (1983)
Synonyms: None known
First Discovery: Sichuan, China
Chart Position: 244

Xiaosaurus dashanpensis

Xiaosaurus was discovered at Dashanpu—an area rich in fantastically preserved fossils, but you can't win 'em all and its remains are, well, a bit poor. Skull fragments, a handful of teeth, a few limb bones and some vertebrae represent the entirety of its remains, and those are from two different specimens, so Xiaosaurus and its meagre, diagnosis-dodging remnants have caused nothing but problems, from a classification point of view.

The original authors assigned it to both Fabrosauridae and Hypsilophodontidae betwixt and between Lesothosaurus and Hypsilophodon which wasn't a good start. Since then it has been tagged as an ornithopod of uncertain affinities, a possible basal member of Cerapoda and a marginocephalian. Mostly, it is considered highly dubious though Paul Barrett (2005) believes it is a "provisionally valid" primitive ornithischian because of the funny shape of its funny bone; its humerus is straight when viewed from the front.

Peng Guangzhao renamed Agilisaurus multidens (now Hexinlusaurus) into a second species of XiaosaurusXiaosaurus multidens—whilst describing Agilisaurus louderbacki in 1992, which isn't a widely publicised fact, mainly because it was never widely accepted.
(Dawn lizard from Dashanpu) Etymology
Xiaosaurus is derived from the Chinese "xiáo" (dawn) in reference to the age of the fossil, and the Greek "sauros" (lizard). The species epithet, dashanpensis, refers to Dashanpu. It's utterly important not to confuse Xiaosaurus with Eosaurus, which is also a "Dawn lizard" but of different dietary preference, age and time. Discovered by Dr. Dawson and Sir Charles Lyell in the coal fields of Nova Scotia in August 1855, that Dawn lizard was sea-dwelling and initially assigned to Ichthyosaurus by O.C. Marsh in 1862. Its remains—two squished verts—are shabby even by Xiaosaurus standards, and it is no longer an official dawn lizard, or even a lizard.
Discovery
The remains of Xiaosaurus were discovered by Dong Zhiming whilst sifting through remains collected from the Lower Shaximiao (Xiashaximiao) Formation during a 1979-1980 field season at Dashanpu, Zigong, Sichuan Province, China.
The holotype (IVPP V6730A) consists of a jaw fragment with a single tooth, two cervical (neck) vertebrae, four caudal (tai) vertebrae, a humerus (funny bone), a partial left femur (thigh) and a complete right hindlimb. More remains (IVPP V6730B) including a right femur, a dorsal (back) vertebra, two sacral (hip) vertebrae, a phalanx (toe bone), a rib and two teeth were later assigned, though they have since been misplaced.
Estimations
Timeline:
Era: Mesozoic
Epoch: Middle Jurassic
Stage: Bathonian-Callovian
Age range: 181-161 mya
Stats:
Est. max. length: 1 meters
Est. max. hip height: 0.3 meters
Est. max. weight: 6 Kg
Diet: Herbivore
Family Tree:
Dinosauria
Ornithischia
Genasauria
Neornithischia
Xiaosaurus
dashanpensis
References
• Z. Dong and Z. Tang (1983) "New ornithopod genus from the Middle Jurassic of Sichuan Basin, China".
• O.C. Marsh (1863) "Description of the Remains of a new Enaliosaurian (Eosaurus Acadianus), from the Coal-formation of Nova Scotia".
• Paul M. Barrett, Richard J. Butler and Fabien Knoll (2005) "Small-bodied ornithischian dinosaurs from the Middle Jurassic of Sichuan, China".
• Peng, G.-Z. (1992) "Jurassic ornithopod Agilisaurus louderbacki (Ornithopoda: Fabrosauridae) from Zigong, Sichuan, China".
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To cite this page:
Atkinson, L. "XIAOSAURUS :: from DinoChecker's dinosaur archive".
›. Web access: 27th Apr 2017.
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