ANN ARBOR, Mich., May 2 (UPI) -- Researchers say the large number of carnivore fossils found in a Spanish cave suggest it had a "killer" entrance that trapped animals intentionally entering it.
Soledad Domingo from the University of Michigan along with colleagues from other institutions said a large assortment of saber-toothed cats, hyenas, an extinct "bear-dog," ancestors of the red panda and several other kinds of carnivores died under unusual circumstances in the cave near Madrid between 9 million and 10 million years ago.
Previous theories about the abundance of the carnivore fossils had suggested mass mortality, accidental falls into the cave or that the animals died in other locations and were washed into the cave, but none of the theories could account for the absence of herbivores or the large number of apparently healthy adults among the remains, researchers said.
Writing in the journal PLoS ONE, the researchers suggest the animals most likely intentionally entered the cavity in search of food or water over a protracted period of time and died in the cave because they couldn't get out.
The scarcity of herbivore remains may indicate the cave entrance was clearly visible and thus avoided by these animals, they said.
The researchers said they based their conclusions on the demography of the individuals recovered, the orientation of the remains and scarcity of fractured bones or trampling marks.