Experimental Study of Taphonomical Process of Animal Remains, Especially Molluscs in Shell Midden

在本研究中，我进行了两种类型的实验贝冢在亚热带冲绳本岛和贝冢的发掘分析。第一种类型的实验贝冢在空的贝壳在2毫米网眼袋，并设置在石灰石次生林。许多类型的“仍然”，如按钮和珠子，是不同的形状和重量放在每个壳贝冢。3年后，实验贝冢被挖掘出来。“遗迹”是指根据基质壳的大小和遗迹的性质不同而有不同的沉积方式。这种现象是由土壤动物如千足虫和陆生等足类的活动引起的。第二种是在沿海地区的贝壳上制作实验贝冢，以评价土壤动物的活动。大型有盖蜗牛壳，涡轮，曾用于陆地寄居蟹，Coenobita，并从实验壳垃圾场。这一证据可能出现在史前贝冢上，因为出土的Turbo的鳃盖数量比贝壳多。比较干净的壳和壳包括腐烂的肉的土壤动物的数量和组成没有什么不同。对桑迪考古遗址贝壳类的种类组成和丰度的垂直变化进行了分析。贝壳可分为中大型可食种、小型不可食种、大型陆生种和微小陆生种4类。三种类型的垂直变化被确认为四个组，中大型食用种，微小的陆生种和其他。可食用贝类的倾倒和其他类群在贝冢上的沉积是贝冢动物遗骸形成的两个因素。

In the present study, I conducted analysis of two types of experimental shell middens at subtropical Okinawa-jima Island and excavations of shell midden.First type of experimental shell midden made on empty shell in the 2 mm mesh baggage, and set on limestone secondary forest. Many types of "remains" such as buttons and beads that are different shape and weight put on each shell middens. After 3 years, experimental shell middens were excavated. "Remains" were deferent mode of depositions according to size of matrix shells and character of remains. This phenomena were caused by activity of soil animals, such as millipedes and terrestrial isopods.Second type of experimental shell midden made on shell at the coastal area to evaluate the activity of soil animals. Large operculated snail shells, Turbo, had used on land hermit crabs, Coenobita, and were moved from the experimental shell midden. This evidence would be occur on prehistoric shell middens because excavated number of operculums of Turbo had be higher than shells. Comparison of number and composition of soil animals to clean shells and shells including rotten meat were not different. Therefore, soil animals will use the shell midden to shelter.Analysis of vertical changes of species composition and abundance of shells were made on archaeological sits of sandy dune. Shells were divided four groups, middle to large edible species, small non edible species, large terrestrial species and minute terrestrial species. Three types of vertical changes to four groups were recognized, middle to large edible species, minute terrestrial species and others. Two factors, dumping the edible shells and depositing the other groups on shell midden would exist the formation of animal remains on shell midden.