陕西蓝田晚中新世灞河组鼠科化石

详细描述了陕西蓝田晚中新世灞河组发现的两种鼠科化石 :中华原裔鼠Progonomyssinensissp .nov .和Muridaegen .etsp .indet.。新种的特征是 :个体通常比ProgonomyscathalaiSchaub ,1 938大 ;下臼齿的唇侧齿带和附属尖很弱 ;三分之二的m1具有一很小的中间前边尖(tma) ;M1的t1和t3偶见后刺 ,在个别的m1中有一短的中间脊 ;臼齿的尺寸落入P .woelferi的变异范围 ,但t6～t9间的连接没有该种那样常见 ,而t1 2较为明显。新种产于灞河组下部层位 ,其牙齿的大小和形态特征介于ProgonomyscathalaiSchaub ,1 938与P .woelferiBachmayeretWilson ,1 970之间。据此可证实 ,把灞河组下部层位的时代置于晚中新世早期 ,相当欧洲瓦里士期晚期或MN1 0的时代比较恰当。新种的重要意义不仅在于它具有狭义Progonomys属的特征 ,而且是我国现知鼠科动物最古老的一种。未定种产于灞河组较上部层位 ,牙齿形态与Progonomyssinensis的相似 ,很可能与其有较接近的亲缘关系。

MURIDS FROM THE LATE MIOCENE BAHE FORMATION,LANTIAN,SHAANXI

Two forms of Muridae, Progonomys sinensis sp. nov. and Muridae gen. et sp. indet. from the late Miocene Bahe Formation at Lantian, Shaanxi Province are described. The new species, occurring in lower horizons of the formation, demonstrates intermediate characters between P. cathalai and P. woelferi in dimension and morphology. The new murid argues for an age of early late Miocene for the lower portions of the Bahe Formation, corresponding to early Baodean of Chinese Land Mammal Age, which can be correlated with late Vallesian or MN10 of Europe. Consequently, the new species is important because it represents diversity in the species of the genus Progonomys and the oldest murid known in China. The indeterminate species was probably closely allied to the new species.