Fidelity of terrestrial vertebrate fossils to a modern ecosystem

An exceptionally rich paleontological site, well-dated with 18 radiocarbon samples and containing 10,597 identified mammalian fossils, shows a high affinity to the local habitat with little evidence of long-distance transport of faunal elements. The organic deposits in Lamar Cave, Wyoming, are composed almost entirely of the decomposed collections of wood rats (Neotoma cinerea) and carnivores, mainly wolves (Canis lupus) and coyotes (Canis latrans). The fossil sample, whether analyzed by level or as the total site accumulation, more closely approximates the local living fauna than a modern raptor-pellet and carnivore-scat collection does. The combination of taxa from all but 2 out of 16 levels unambiguously describes the mammalian community of the local sagebrush grassland. Absence of certain extralocal species clearly reflects lack of long-distance (>5 km) transport of non-sagebrush grassland species. If the aim of a paleontological study is specifically to reconstruct the local mammalian community, these data demonstrate that only a minimum of sampling effort may be required for similar localities. However, the data from Lamar Cave do demonstrate that if the goal of a paleontological, or in fact modern, study is to tally the total number of species, an intensive sampling effort is required in order to include the rare taxa. Though time-averaged records indeed may obscure some analyses, particularly those of discerning disharmonious faunas such as those found at the Pleistocene–Holocene transition, this study shows that some time-averaging will benefit the interpretation of faunal diversity of both present and past ecosystems by inclusion of less common taxa.