How robust is the taphonomic method in microvertebrate research? Analytical error evaluation in taphonomic data from hominin-bearing Layer C of Tabun Cave

Various predators are known to have ubiquitously contributed to the accumulation of fossil microvertebrate assemblages in Quaternary depositional settings. Deciphering the taxonomic identity of the predator responsible for each such assemblage through detailed taphonomic analysis has become a prerequisite for paleoecological research to gain insight into their prey and foraging habitat preferences. However, this flourishing field of research builds on the assumption that the pristine taxon-specific taphonomic signal of various predators could have become preserved in the fossil record, unbiased or only negligibly biased by a wide array of destructive post-depositional processes, which could introduce noise into the preservational system. Here we evaluate the likelihood that the predator taphonomic imprint could have been entirely obliterated by such post-depositional action within an especially large assemblage of the remains of micromammals (Rodentia, Eulipotyphla, and Chiroptera; N = 25,810) from Middle Paleolithic Layer C of Tabun Cave, Mount Carmel, Israel. The microfauna from this major stratigraphic unit (c. 2.5 m thick; uniquely yielding the fossils of both Homo sapiens and Neanderthals), with a mean chronometric age of c. 165 ka, has no contemporary analogues in the regional record, indicating exceptional paleoecological conditions for its timespan. We took advantage of the fact that Layer C (aka a major stratigraphic unit) was subdivided in more recent excavations into as many as 26 separate layers (aka beds), featuring relatively nuanced differences in sedimentary, diagenetic, and anthropogenic characteristics, to both independently assess the possibility that Layer C as a whole is isotaphonomic and evaluate the extent of taphonomic variation from bed to bed within it. While substantial variation and bias were revealed in a broad array of standard taphonomic indices of skeletal element fragmentation and differential representation, one index—the grading of digested molars according to the severity of digestion—proved robust against post-depositional distortions of the predatory signal. We discuss the implications of these findings for reliable taphonomic and paleoecological assessment in research with microvertebrate fossil remains.