| Yandusaurus | |
|---|---|
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| Life reconstruction ofYandusaurus | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | †Ornithischia |
| Genus: | †Yandusaurus He,1979 |
| Species: | †Y. hongheensis |
| Binomial name | |
| †Yandusaurus hongheensis He, 1979 | |
Yandusaurus is agenus of herbivorous basalneornithischiandinosaur from theBathonian age (middleJurassic, approximately 168 to 162Ma) ofChina.
In January 1973 the Museum of the Salt Industry atZigong inSichuan was warned that during construction activities with acomposter atJinzidang near the Honghe dam inadvertently a dinosaur skeleton had been processed. A team of the museum managed to salvage some heavily damaged remains. Though locally this animal was at first referred to as "Yubasaurus" or "Honghesaurus", in 1979Beijing professorHe Xinlu named and described it as thetype speciesYandusaurus hongheensis. The generic name is derived fromYandu, the ancient name for Zigong. This name is a contraction ofyan, "salt", anddu, "capital", occasioned by the fact that Zigong was historically the centre of Chinese salt mining. In this wayYandusaurus indirectly also refers to the Salt Museum. Thespecific name refers to the Honghe river.[1]
Theholotype specimen,GCC V20501, had been dug up in a layer of theLower Shaximiao Formation. It consists of a partial skeleton with skull. Elements of most parts of the body have been preserved, the skull, vertebral column, shoulder girdle, frontlimbs and hindlimbs but all are very limited and/or damaged. The lower jaws, pelvis and the end of the tail had probably been entirely destroyed by the machine.[2]
In 1983 He andCai Kaiji identified a second species:Yandusaurus multidens, known from two nearly complete skeletons and nine partial skeletons.[3] In 1992 this was byGuangzhao Peng reassigned to the genusAgilisaurus as aA. multidens. In 1996Gregory S. Paul renamed it asOthnielia multidens. In 2005 it was byPaul Barrett e.a. placed in its own genus,Hexinlusaurus.[4]
A fast-moving biped,Yandusaurus had four toes on each foot and five fingers on each hand. It had large eyes as shown by the curvedjugal. The teeth, showing a unique pattern of parallel vertical ridges compared by Chinese researchers to the fingers of the hand of Buddha statues, are very asymmetrical in that the inner side is strongly worn down. The fifteenmaxillary teeth are largest in the middle and overlap.[2]
When indicating the size ofYandusaurus many sources give that ofHexinlusaurus, the previousY. multidens, the (all juvenile) specimens of which are sixty centimetres (two feet) to 1.6 metres (5 ft) in length, and weighed around sevenkilograms (fifteenlb).Yandusaurus hongheensis was however considerably larger than these exemplars: He estimated the body length at three metres,[2] Peng at 3.2 metres; in 2010 G.S. Paul gave an estimation of 3.8 metres length and a weight of hundred forty kilogrammes.[5]
Yandusaurus was assigned by He to theHypsilophodontidae.[1] Today however Hypsilophodontidae is considered an unnatural (paraphyletic) group andYandusaurus is viewed as taking an unresolved position withinNeornithischia.[6][7]
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