Taphonomy of the Miocene bone accumulations at Paşalar, Turkey

Abstract

The bone assemblage from the Miocene deposits at Paşalar, Turkey is described. The fossil bones are concentrated in a single horizon of poorly sorted sands and gravels which were accumulated rapidly. The source of the sedimentary particles was the lower slopes of the hills bordering the site, and the distribution of bones relative to sediment shows that they were transported to the burial site as part of the sedimentary load. Bone size and distribution are correlated with particle size, and orientations and dips of the bones are indicative of turbulent flow during deposition. It is concluded, therefore, that the bones came from the same source area as the mineral constituents of the sediments, namely from the lower hill slopes close to the site. The fossil bones are extremely fragmentary, with isolated teeth being the most common parts preserved, and some of this breakage may be attributed to the effects of transport. The majority of bones are edgerounded, and in most cases the abrasion is superimposed on weathered and broken surfaces, indicating that the bones accumulated and were broken before abrasion. The bone degradation caused by these processes has resulted in the destruction of all but the strongest elements, but it does not appear to have selectively destroyed particular faunal elements. Predator activity is demonstrated for small mammals by the presence on some of their preserved teeth of surface corrosion caused by digestion, and it is inferred for large mammals by age structure anomalies in the samples of certain of the larger sized species. The biases introduced by these processes are considered to be loss of the smallest size groups of small mammals and over-respresentation of rhinocerotids and giraffids, but apart from this the fossil assemblage approximates to a life assemblage accumulated over a short period of time and from a limited geographical area.