出典:Wikipedia
出典:『Wikipedia』 (2011/06/10 01:25 UTC 版)
Acristatherium yanensis is an extinct basal eutherian from the Early Cretaceous (early Aptian, approximately 123 million years ago) Lujiatun Bed of the Yixian Formation. It was described on the basis of a single specimen (holotype) from Beipiao, Liaoning, China by Yaoming Hu, Jin Meng, Chuankui Li and Yuanqing Wang in 2010. The specimen comprises a partial skull, 25 millimetres (0.98 in) long. It appears to possess a vestige of a septomaxilla, a feature only otherwise seen in non-mammalian therapsids.