中文摘要：

爪兽是一类奇特的绝灭的具爪的奇蹄动物.新近纪以来的爪兽是非常典型的食叶动物,因而可以作为森林环境的指示物种.近些年的考察,除在柴达木盆地东部外,在盆地中西部也发现了爪兽化石的踪迹,本文记述了新发现的这批晚中新世早期的爪兽头后骨骼化石.在我国,爪兽的头后骨骼非常少见,因此新材料增加了我们对爪兽骨骼解剖学的认识.同时,爪兽化石的新发现也指示出中中新世晚期至晚中新世早期,柴达木盆地东、中西部地区具有以草原为主、森林间杂其间的古环境面貌.

英文摘要：

Qaidam Basin is located at the northeast of the Qinghai-Tibet Plateau and is the third largest basin in China.In this basin, the environment is very arid and cold, but it should be much better than now in the geological history.The mammalian fossils found from in the basin recorded the great vicissitude from wet and warm to arid and cold. In the Qaidam Basin, some new chalicothere fossils have been found from the Tuosu Fauna of the early Late Miocene（early Bahean Chinese Land Mammal Stage/Age）at the Quanshuiliang area and the Eboliang Ⅲ Anticline.These fossils are represented by one lunate, two phalange Ⅰ s, two phalange Ⅱ s, one phalange Ⅲ of manus and one phalanx Ⅰ of pes. The postcranial bones of fossil chalicotheres are very rare in China.These new specimens thus add to our knowledge about chalicothere anatomy.The lunate （V 20278.1） is an irregular polyhedron, having well developed volar process, large ulnar lower scaphoid facet and very weak ulnar upper scaphoid facet.Its size is larger than any other known chalicothere. Phalange Ⅰ s of manus （V 20278.2~3） are strong and large.The proximal part is much wider than the distal part.The proximal articular facet（Mc）inclines strongly in the dorsal direction.This facet is concave and has no sagittal groove.The proximo-volar tubercles are symmetrical and separated by a shallow V-shaped groove. Phalange Ⅱs of manus（V 20279~20280）are much depressed in ulnar-radial section.The distal articular facet, greatly developed, is like a trochlea.The proximal articular facet is divided into two symmetrical depressions by a middle longitudinal ridge. Phalange Ⅲ（V 20281）is a bifid claw as in other late chalicotheres but it is a little larger in size.The chalicothere fossils from the Qaidam Basin were first described by Bohlin （1937） as Ancylopode sp.In 2001, Wang and Wang added a mandible fragment with m2~m3 from the Olongbuluk Fauna（MN8）of the Huaitoutala Section.In this study, we regard all the chalicothere fossils from the Q