BEIJING, Jan. 9 (Xinhuanet) -- Our primitive cave-dwelling ancestors did not have to deal with dangerous dinosaurs, despite Hollywood portrayals to the contrary, but they did have to stay clear of saber-toothed cats, dire wolves, giant man-eating birds of prey and cave bears a third larger than modern grizzlies.

    Scientists used to think cave bears were vegetarians that mostly fed on berries and roots. But, now bones from the Carpathian mountains suggest cave bears could have also been carnivores, and possibly even cannibals.

    Cave bears (Ursus spelaeus) are named after the places where their bones are commonly found — caves across Europe. They died out roughly 20,000 years ago, when ice dominated the Earth.

    For the past 30 years, studies of their skulls, jaws and teeth suggested cave bears might have been largely herbivorous.

    In addition, the bones of central and western European cave bears matched those of vegetarians in having low levels of nitrogen-15, whose atomic nucleus has one more neutron than common nitrogen-14 does. Animals accumulate nitrogen-15 in their bodies, and animals that eat animals — that is, carnivores — build up more nitrogen-15 than herbivores do.

    New data from the Pestera cu Oase ("Cave with Bones") in the southwestern tip of the Carpathian mountains in Romania now hints most of its cave bears were significantly carnivorous, due to their high nitrogen-15 levels.

    "It is a pretty inaccessible cave that you need to go underwater to get to," said researcher Michael Richards, an archaeologist at the Max Planck Institute for Evolutionary Anthropology at Leipzig, Germany. "It would be interesting to measure more cave bears from other sites in this region to see if we find other carnivorous cave bears."

    The researchers suggest the cave bears might have eaten fish, but another possibility is "some degree of bear-bear cannibalism," said University of Arizona zooarchaeologist Mary Stiner, who did not participate in this study.

    In brown bears, "cannibalism and eliminating rivals and young go hand in hand, as in lions. This behavior is also clear from very large cave bear tooth marks on young cave bear skulls in Yarimburgaz Cave in western Turkey."

    (Agencies)