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

点击翻译按钮获取中文摘要

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.