Texas Tech Biologist Collaborates in Study That Finds Extinct Horned Crocodiles Ate
March 9, 2010
This crocodile occasionally robbed from the Cradle of Mankind in Africa’s Olduvai
Gorge about 2 million years ago.
With devilish horned ridges above each eye, Crocodylus anthropophagus probably
waited patiently for prey to come a little too close to the water’s edge before snapping
its huge jaws on its victims and sealing their doom.
Now, a Texas Tech University professor says this crocodile occasionally robbed from
the Cradle of Mankind in Africa’s Olduvai Gorge about 2 million years ago.
Lou Densmore, interim chairman of the Department of Biology, said Crocodylus anthropophagus
appears to have dined on early human ancestors.
“This croc was probably a little bit larger than the Nile crocodile,” Densmore said.
“Five meters (16.4 feet) would not be out of the question.”
Densmore contributed to a recent study led by Chris Brochu, an associate professor
in the Department of Geosciences at the University of Iowa. Their findings appeared
in the Feb. 24 issue of the journal PLoS ONE (Public Library of Science).
“I remember when Chris 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
The startling dietary evidence was discovered while Brochu and his collaborators were
reconstructing 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. “As far as we can tell,
there was only one crocodile living in that area at that time. I wasn't especially
interested in how these crocodiles interacted with human ancestors. Much of that angle
was contributed by our co-authors Jackson Njau at the National Natural History Museum
in Tanzania and Robert Blumenschine at Rutgers University. They have been studying
the paleo-ecology of hominids in Olduvai Gorge for many years.
“To me, a primate is a primate. I work on things that eat primates, not primates.”
Brochu originally thought that the fossilized crocodile remains would be the same
as the Nile crocodiles found in East Africa. However, after close inspection of the
horned brows over each eye and other differences, the researchers determined this
was a separate 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.”
That surprised researchers because although crocodile diversity was higher in Africa
up until the start of the Ice Age 2 million years ago, most scientists assumed croc
diversity nosedived with the onset of a cooler world, Brochu said.
“That diversity remained relatively high as recently as 1.8 million was a real surprise,”
Densmore, whose expertise lies in studying genetic and molecular differences in modern
crocodiles, was involved in the research primarily because of the importance this
work might have for understanding modern crocodile diversity in Africa.
He said there’s growing evidence that the modern, wide-ranging Nile crocodile may
actually represent two or more independent but similar looking species. No one has
looked to see if all the Nile populations with differing body types are also genetically
“Adding fossils to the analysis increases our abilities to address both issues,” Brochu
said. “It’s been primarily through my collaborations with Lou and his students that
we’ve been able to take this work to the next level, integrating information from
the fossil record with information from living crocodiles.”
Densmore will continue his collaboration with Brochu to work on still more crocodilian
fossils from Africa that are 5 to 7 million years to determine if they might be a
close relative of the crocodiles currently living in the Caribbean. Also, the researchers
will study a truly giant crocodile that might have exceeded 26 feet in length.
CONTACT: Lou Densmore, interim chairman, Department of Biology, Texas Tech University, (806) 742-2710 or firstname.lastname@example.org.