Temporal range: Early Cretaceous, 125Ma
You et al., 2003
Discovery and naming
The type (and only known) specimen was found in the summer of 2000 by a Chinese-American expedition in the Mazong (= "horse mane") Shan area of China's Gansu Province. In 2002 You Hialu in a dissertation named and described the species Equijubus normani. The generic name is derived from Latin equus, "horse", and juba, "mane". The specific epithet "normani" is in honour of British palaeontologist David B. Norman. However, such a nomen ex dissertatione does not constitute a valid name.
The type specimen or holotype, IVPP V12534, consists of a complete skull with articulated (attached) lower jaws, plus associated incomplete postcrania: nine cervical (neck), sixteen dorsal (back), and six sacral (pelvic) vertebrae. It was found in fluvio-lacustrine sediments of the Middle Grey Unit of the Xinminbao Group, Gonpoquan Basin, Mazong Shan, Gansu Province, China.
Equijubus is a relatively large euornithopod. Gregory S. Paul in 2010 estimated the length at seven metres, the weight at 2.5 tonnes. A palpebral bone seems to be absent, meaning the eyes were not overshadowed by an upper rim as with most related species.
Equijubus was described as a basal hadrosauroid dinosaur, although it may turn out to be a non-hadrosauroid iguanodont. The discoverers considered it to be the basal-most of the hadrosauroids, and suggested that this group emerged in Asia.
- You, Luo, Shubin, Witmer, Tang and Tang (2003). "The earliest-known duck-billed dinosaur from deposits of late Early Cretaceous age in northwest China and hadrosaurid evolution." Cretaceous Research, 24: 347-353.
- You Hailu, 2002, Mazongshan dinosaur assemblage from late Early Cretaceous of northwest China. Dissertation University of Pennsylvania 164 pp
- Paul, G.S., 2010, The Princeton Field Guide to Dinosaurs, Princeton University Press p. 292