甘肃兰州盆地咸水河组下段红色泥岩中的跳鼠化石

DIPODIDAE (RODENTIA, MAMMALIA) FROM THE LOWER MEadER OF XIANSHUIHE FORMATION IN LANZHOU BASIN, GANSU, CHINA

兰州盆地咸水河组下段上部红色泥岩共产有４属８种跳鼠：Ｐａｒａｓｍｉｎｔｈｕｓ ａｓｉａｅ－ｃｅｎｔｒａｌｉｓ， Ｐ． ｔａｎｇｉｎｇｏｌｉ． Ｐ． ｐａｒｖｕｌｕｓ Ｐａｒａｓｍｉｎｔｕｓ． ｓｐ． Ｉ， Ｐａｒａｓｍｉｎｔｕｓ ｓｐ． ＩＩ，黄河简齿鼠（新属、种）Ｌｉｔｏｄｏｎｏｍｙｓ ｈｕａｎｇｈｅｅｎｓｉｓ ｇｅｎ．ｅｔ ｓｐ．ｎｏｖ、，兰州异蹶鼠（新种）Ｈｅｔｅｒｏｓｍｉｎｔｈｕｓ ｌａｎｚｈｏｕｅｎｓｉｓ ｓｐ．ｎｏｖ．和Ｓｉｎｏｓｍｉｎｔｈｕｓ ｓｐ。Ｌｉｌｏｄｏｎｏｍｙｓ，ｈｕａｎｇｈｅｅｎｓｉｓ的主要特征是颊齿比例上较宽短，冠面结构较简单，脊较发育，下中脊短或无，下外脊直接由下原尖伸出。Ｈｅｔｅｒｓｍｉｎｔｈｕｓ ｌａｎｚｈｏｕｅｎｓｉｓ为Ｈｅｔｅｒｏｓｍｉｎｔｈｕｓ属的一较原始的种。它的臼齿的颊、舌侧主齿尖虽错位，但幅度还较小，Ｍ１／２具原小尖，但无原附尖，ｍｌ具发达的下中脊，下外脊折线形，下外中脊向前倾等。 兰州盆地下红泥岩所产跳鼠组合基本上与甘肃省党河流域Ｔａｂｅｎ－ｂｕｌｕｋ的一致。它们的时代可能大致相当，为晚渐新世。 本文用 ＰＡＵＰ３．１．１对早第三纪的各跳鼠属间的关系作了分析和讨论。 跳鼠在?

The dipodid fossils from the red mudstone of the bower Member of the Xianshuihe Formation include eight species of four genera: Parasminlhus asiae-centralis, P. tangingoli, P. parvulus, Parasminthus sp. I, Parasminthus sp. II, Litodontomys huangheensis gen. et sp. nov., Heterosminthus lanzhouensis sp. nov., and Sinosminthus sp. The new genus Litodontomys can be diagnosed as: having proportionally wider and shorter cheek teeth, with simpler occlusal pattern, well developed lophids, mesolophid short or absent, ectolophid extending from protoconid. The new species Heterosminthus lanzhouensis represents a primitive species of Heterosminthus. The main cusps of its molars are slightly alternate in position. The protoconule is distinct hilt the anterostyle is absent on M1/ 2. ml has developed mesolophid, bending ectolophid, and antero-buccally oblique ectomesolophid. The dipodids described above are similar to those of Taben-buluk in composition. The middle part of the lower red mudstone bearing the dipodids may be equivalent to that of the latter in age. It is of late Oligocene. The phylogenetic relationships of the Paleogene dipodids are analyzed based on dental features using PAUP 3.l. 1. The predominance of the dipodids in the late Oligocene micromammals in the Lanzhou Basin indicates that a grassland or savanna habitat might have been established in the Lanzhou area during that time.