| Several taxa of large carnivores co-occurred during the late Pleistocene in the steppe-tundra
ecosystem, such as wolf Canis lupus, cave lion Panthera leo spelaea, cave hyaena Crocuta
crocuta spelaea, brown bear Ursus arctos and cave bear Ursus spelaeus and Ursus ingressus.
This abundance of taxa belonging to the same guild raises questions about niche partitioning,
especially in terms of dietary specialization and prey selection. Observations of the
dietary ecology of the extant relatives of these late Pleistocene carnivores does
not provide unambiguous answers as these populations live under very different
environmental conditions where other potential prey species are present, but it appears that
most of these modern large carnivores are relatively flexible in their prey selection.
Palaeontological investigations dealing with faunal associations and activity marks on fossil
bones also have their limitations, such as taphonomic biases (palimpsests rather than
biological associations) and do not allow the quantification of consumption of various
preys.
In contrast, carbon and nitrogen isotopic signatures of bone collagen depend directly on
those of the average diet. Since different potential prey species occurring in the steppe-tundra
exhibit consistent isotopic differences for these chemical elements, it is possible to relate the
carbon and nitrogen isotopic signatures measured in fossil carnivores with the preferential
consumption of some prey species. Some amount of quantification can be provided using
modified versions of mixing models developed for modern ecosystems. In addition, this
isotopic approach is individual-based and it is therefore possible to investigate intra- and
inter-population differences in prey selection, as well as possible chronological trends and
differences linked to genetic differences by combining isotopic and ancient DNA studies on
the same material.
The isotopic approach has already shown that among the tested large carnivores, cave
bears of various genetic types are overwhelmingly vegetarian while coeval brown bears are
essentially carnivores, cave lions have a marked preference for reindeer, and none of the large
carnivores match Neanderthals in terms of megaherbivore consumption (i.e. woolly
mammoth and woolly rhinoceros). |