New evidence suggests that our human ancestors 2 million years ago were eaten by a large crocodile that lurked at the water's edge before closing its jaws on victims and drawing them under to their death.
(Early hominids, possibly belonging to the species Homo habilis, were eaten by a prehistoric crocodile. Credit: Lillyundfreya)
The newly identified Pleistocene croc Crocodylus anthropophagus, described in a recent PLoS One paper, robbed from the Cradle of Mankind in Africa's Olduvai Gorge, according to co-author Lou Densmore and colleagues.
"This croc was probably a little bit larger than the Nile crocodile," said Densmore, interim chairman of the Department of Biology at Texas Tech University.
"Five meters (16.4 feet) would not be out of the question."
He added, "I remember when Chris (colleague Chris Brochu) sent me the first draft, he said ‘I think we should name it anthropophagus. Do you think people will get the joke?' I said ‘I think they'll get the joke. I think it's a pretty good idea.' Clearly, we don't think this crocodile's primary diet was hominid. But fossil evidence shows hominids and crocodiles encountered each other."
The scientists discovered the croc dietary evidence during an investigation of the evolutionary history of Africa's crocodiles.
"Hominid bones from Olduvai-area rocks of the same age as C. anthropophagus show bite marks interpreted as coming from a crocodile," Brochu said.
In the study, he and his colleagues write: "Curiously, the tooth mark patterning on both (human) specimens indicates that each hominid individual lost its left foot to crocodiles during or shortly after capture, or when being scavenged."
Homo habilis is mentioned as being the possible hominid victim. This early human was relatively small, at least compared to the croc, so the researchers suggest that the predator was somewhat small for its species, perhaps a juvenile, since larger adult crocodiles "would be capable of consuming hominids completely, leaving no trace."
They add, "Crocodiles may have been common hominid predators, and as such should be considered in discussions of the ecological context of human origins."
At first Brochu thought the fossilized crocodile remains belonged to the well-known Nile crocodile, but he and his team noticed horned brows over each eye and other differences, so they knew they were dealing with a new species.
"Much of the work that Chris has done was to figure out which crocodile this animal was most closely related to," Densmore said. "It looks like it was most likely related to the Nile crocodile. Before, there was a possibility that this animal was just a distinct population of Nile crocodiles. But we don't think so. There are enough different characteristics that appear to make this a unique species."
The scientists are already planning their next projects, one of which will be to study a crocodile that might have exceeded 26 feet in length.