COPROLITES OF BONE-CRUSHING CARNIVORES: ABUNDANT IN THE OLD WORLD, RARE IN THE NEW WORLD

Several lineages of dogs and hyenas evolved bone-crushing adaptations (robust skulls, jaws, teeth, large masticatory muscles). The ingestion of abundant bone material produces feces composed entirely of hydroxyapatite powder, which facilitates their preservation.

The most common carnivore coprolites (and vertebrate coprolites of any kind) in the Old World (Africa, Europe, Asia) in the Late Cenozoic pertain to hyenas (>200 localities) - acme in the Late Pleistocene, but locally common as early as the Miocene. The majority are from Europe and Asia and represent the Cave Hyena Crocuta crocuta spelaea (Hyaenacopros bucklandi), with a small number of Early-Middle Pleistocene occurrences attributed to the Brown Hyena Parahyaena brunnea and a larger number to the Giant Short-faced Hyena Pachycrocuta brevirostris. Identification is usually based on associated skeletal material. Hyena coprolites can be identified as rounded segments, ranging in morphology from conical to cylindrical, that are typically white in color and contain bone fragments. Coprolites of bone-crushing hyenas are disproportionately represented in the fossil record, not only because of composition, but also due to: (1) social and denning behavior, resulting in large accumulations; (2) habitation in caves, which enhances the potential for preservation; and (3) ability to transport and redeposit coprolites. Some bias is introduced by the fact that hyena coprolites are so readily identifiable, even as fragments, compared to the bromalites of other carnivores.

Bone-crushing hyenas are absent in the New World, but borophagine canids are ecological equivalents. There are three localities with coprolites of Borophagus in open air sites, two in the Mehrten Formation (latest Miocene) of Stanisalus County, California, and one in the Pearson Mesa Formation (early late Blancan) of Hidalgo County, New Mexico.

There are two distinct biogeographic and taphonomic provinces of vertebrate coprolites in the Late Cenozoic, principally from caves: (1) Castrocopros province of the New World characterized by a dominance of herbivore coprolites but also borophagine coprolites; and (2) Hyaenacoprus province in the Old World, which is dominated by hyena coprolites. Thus, different coprolites of bone-crushing carnivores characterize these provinces.