关键词: 禄丰古猿化石产地;最晚中新世动物群;啮齿目;低冠竹鼠

Abstract: Lufeng rhizomyid fossils collected by exeavation and underwater sieving of fossili-ferous sediments, are studied in this paper.
The specimen referable to Brachyrhizomys nagrii is a left lower dentition with M1—M3(V. 8126) . Length of M1-M3, is 11. 75 mm. Both size and characters (such as short M3 and an elongated mesolophid on M3 ) agree well with Siwalik specimens (Fig. 4).
The specimens identifiable to Brachyrhizomys ef. B. pilgrimi are a left dentary with M1—M3 (V8127. 1) , a right M3 (V8127. 2) and an I1 (V8127. 3) . This is a large species with heavy deep dentary (depth below M=15. 4 mm) and massive incisors. It also is the biggest one of three species of Lufeng Brachyrhizomys. An apparent trait is suppression of mure on Mo-3. The narrow connection may not be present in early wear. Length of M-Ms is 15. 6 mm and more closer to B. ef. pilgrimi than to B. pilg- rimi of Siwaliks in size (Fig. 5, A, B and C).
The third species is B. tetracharax to which the most of the rhizomyine fossils from Lufeng Ramapithecus locality belong. The materials include an incomplete skull and associated lower jaw (V8128. 1) , five maxilla fragments (V8128. 2—6) . fourteen lower jaws (V8128. 7-20) . Fifty five isolated upper and lower ehack teeth (V8128. 21-75) , eleven isolated upper and lower incisors (V8128. 76—86) . Unfortunately, the skull and assoeiated lower jaw are crushed and fiattened laterally (Fig. 6, A) . The portions of it preserved are the ear region of two sides, partial right palate and left zygoma、partial maxilla, premaxilla, temporal bone and nasal. The infraorbital foramina were damaged and the shape of their ventral slit ean not be observed. The dentary is deep. In general, the upper dentition is longer than the lower one. Average length of them is 12. 28 mm and 14. 30 mm respectively. It is undoubtedly to refer the specimens from Lufeng to B. tetracharar, although there is discrepaney between the dimensions of the cheek teeth of Lufeng and Siwalik. M' has four roots. Ma elongates transversely. There is a strong mesolophid on M2 and an evident mure on worn M2-3. M, extends longitudinally. These traits distinguish the specimens from the other speeies easily. The yariations of upper and lower eheek teeth manifested by differences of wear stage in size and pattern of occlusal surface are shown in Fig. 6.
In addition, two isolated cheek teeth are referred to Rhizomyidae indet. A right M' with four roots (V8129) possesses an antero-lingual flexus (Fig. 7) . Another right M5 with a root (V8130) has been well worn and only retained lingual reentrant and three enamel lakes on oeclusal surface (Fig. 8).
The best known record of rhizomyid evolution is doeumented in Siwaliks of Pakistan. It is considered to be a standard for comparison of fossil rhizomyids through. out the world especially Asia. Three species of Brachyrhizomys mentioned above have known temporal ranges in Pakistan and eoexisted for a short time at 8 Ma. So Lufeng hominoid fauna can be placed about 8 Ma or perhaps a bit later.

Key words: Ramapithecus fossil locality of Lufeng; The latest Miocene fauna;