Abstract: The Joint Excavation Team of the Institute of Vertebrate Paleontology and Paleo_x001F_anthropology, Academia Sinica and the Yunnan Provincial Museum excavated at the fossil ape site of Shihuiba, Lufeng County, Yunnan Province (Locality of IVPP 75033) from October to December of 1981.
The excavation area of the 1981 field season is next to that of 1980. The range of the excavation is 20m in length, 5m in breadth and in depth respectively. In addition, we also excavated a part of the sixth layer of the excavation area of 1980 (19m in length, 10m in breadth and 0.3— .5m in depth). A test pit (2m in length, Im in breadth and 3m in depth) was dug at the northern end of the excavation section.
The excavation area is higher than that of 1980 because of typographical differ_x001F_ence. It was divided into two areas： northern area (K) and southern area (J). The thickness, composition and structure of every layer of the new excavation section is- somewhat different from that of the excavation section of the last field season.
The excavation section of 1981 is described as follows.
Excavation thickness is about 5m. Trend NE 30°, from top downward in turn:
Yellow sandy clay with sand and gravel lenses. The clay was contaminated by ferro-magnesium and contains small quartz gravel. These materials came from the slope of hill nearby. There is a thin sandy layer on the bottom of layer 1. It thickens westward. An erosional surface exists between layer 1 and layer 2. Thickness 1.3― .6 m. Dip 220°. Dip angle 5°. More than ten kinds of mammalian fossils (Hipparion etc.) were collected.

Key words: RcMnapithcus; Sivapithecus; Primates; Miocene fauna; Lufeng