Disarticulation and scattering of mammal skeletons

Abstract

I present a statistical technique for determining the disarticulation sequence of vertebrate skeletons based on the relative numbers of different intact joints in an assemblage of bones. For remains of modern Topi (Damaliscus korrigum) on the margin of Lake Turkana, northern Kenya, the disarticulation pattern is very consistent. This sequence, on dry land, differs from that reported for bovids that have disarticulated in the presence of water. On land the bones first released as single bones are those moved least easily by currents of moving water. The last released are those moved most easily. I develop a model of random scattering that suggests that the rate of dispersion is great at high concentrations of bones and decreases rapidly as the distance between bones increases. This leads to a condition where scattering effectively stops. The area of more or less stabilised dispersion is dependent only upon the mean distance that each random event moves a bone. Tests show that it is unlikely that articulated units themselves are much involved in scattering, and scattering appears to take place throughout the course of disarticulation.