Oldupai Gorge in Tanzania is kind of the human race's institute of higher learning. It was one of the places where our ancient ancestors congregated and changed. And it's become famous for the quantity and variety of fossil remains it still holds, giving us way more information about human evolution than we otherwise would have had. We're all alumni of OGU.
But we aren't alone. Other creatures lived in Oldupai besides proto-humans. Some were our food. And some, it seems, might have fed on us.
Crocodylus anthropophagus—that's "man-eating crocodile" for those keeping score at home—lived 1.84 million years ago. Technically, scientists can't say for sure that C. anthropophagus was actually killing people, but there is good, solid evidence that it at least gnawed on them a bit. In a newly published paper researchers analyzed a fossil left foot and a left leg that had once belonged to early hominids and which bear the marks of crocodile teeth. These fossils were found relatively close to fossils of C. anthropophagus. It's not exactly a smoking gun, but it does provide some evidence that the crocodile species and the hominids who'd been bitten by crocodiles lived around the same place and time. Correlation is not causation, but it does wink suggestively, and perhaps flash its sharp teeth.
This paper is a bit weird in that it was accepted for publication back in 2008, but only published this month. In the meantime, a paper that used this research as a source was actually published first. That earlier study described C. anthropophagus as a species. Charles Q. Choi wrote about that earlier paper last year for Livescience. Here's what he had to say about the crocodile, the proto-people, and those tell-tale teeth marks:
Fossil leg and foot bones of at least two hominids from Olduvai bear crocodilian tooth marks, and came from roughly the same time as the newfound horned carnivore and within roughly 300 feet (100 meters) from where the reptile's skeleton was discovered.
"I can't guarantee these crocodiles were killing people, but they were certainly biting them," Brochu said. "Our ancestors would have had to be cautious close to the water, because the water's edge at Olduvai Gorge would have been a very dangerous place."
Crocodiles may have been common predators of hominids, the scientists noted. Larger crocodiles would be capable of consuming our ancestors completely, leaving no trace.
"It was probably as large as a modern Nile crocodile, one of the largest living crocodilians at between 18 to 20 feet," Brochu said. "One thing to bear in mind was that while these crocodiles are not necessarily bigger than the ones today, hominids back then were smaller than we are today, so the crocodiles would have been relatively quite a bit larger."
I'd also recommend reading this dissertation by Jackson Njau, one of the authors on the new paper. In his dissertation, Njau argues that some fossil sites in Olupai, previously thought to be places where human ancestors lived and ate crocodiles, may have actually been places where crocodiles lived and ate human ancestors. If he's right, it's a neat twist. And the dissertation PDF linked here gets into some of the details about the fossil evidence that you can't read in the new, behind-a-paywall paper.