Brochu CA, Njau J, Blumenschine RJ, Densmore LD 2010
A New Horned Crocodile from the Plio-Pleistocene Hominid Sites at Olduvai
PLoS ONE 5(2): e9333 doi 10.1371/journal.pone.0009333
The fossil record reveals surprising crocodile diversity in the Neogene of
Africa, but relationships with their living relatives and the biogeographic
origins of the modern African crocodylian fauna are poorly understood.
A Plio-Pleistocene crocodile from Olduvai Gorge represents a new extinct
species and shows that high crocodylian diversity in Africa persisted after
the Miocene. It had prominent triangular "horns" over the ears and a
relatively deep snout, these resemble those of the recently extinct Malagasy
crocodile Voay robustus, but the new species lacks features found among
osteolaemines and shares derived similarities with living species of
The holotype consists of a partial skull and skeleton and was collected on
the surface between two tuffs dated to c 1.84 Ma, in the same interval near
the type localities for the hominids Homo habilis and Australopithecus
boisei. It was compared with previously-collected material from Olduvai
Gorge referable to the same species. Phylogenetic analysis places the new
form within or adjacent to crown Crocodylus.
The new crocodile species was the largest predator encountered by our
ancestors at Olduvai Gorge, as indicated by hominid specimens preserving
crocodile bite marks from these sites. The new species also reinforces the
emerging view of high crocodylian diversity throughout the Neogene, and it
represents one of the few extinct species referable to crown genus
Ancient Human Ancestors Faced Fearsome Horned Crocodile
A newfound horned crocodile may have been the largest predator encountered
by our ancestors in Africa, researchers now suggest.
Scientists have even found bones from members of the human lineage bearing
tooth marks from this reptile, whose scientific name, Crocodylus
anthropophagus, means "man-eating crocodile."
This predator, which lived some 1.84 million years ago, possessed a deep
snout that would have made it look more robust than modern crocodiles. It
also had prominent triangular horns.
"They would have been visible mostly from the side as projections behind the
eye," said researcher Christopher Brochu, a vertebrate paleontologist at the
University of Iowa. "If you looked at them from the front, you would have
seen ridges projecting upwards."
A couple of living species of crocodile have similar horns, such as the
Cuban and Siamese crocodiles. "Males will use these in mating season to show
off," Brochu explained. "While submerged they kind of tip their head
forward, showing off the prominence of their horns to females."
Scientists found a partial skull and skeleton of the crocodile at Olduvai
Gorge in the Serengeti Plains of Tanzania in 2007. Past research there
famously unearthed numerous fossils of extinct human species and their stone
tools, strengthening the argument that our lineage originated in Africa.
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."
Crocodiles have a reputation for being living fossils that do not change
over time, "and that's just wrong," Brochu added. "If you go back five to
10, 15 million years ago, there were more species of crocodile alive then
than there are now, and the general assumption that once we entered the
Quaternary period, the ice ages, crocodile diversity dropped. This fossil
existed during the Quaternary, so it indicated crocodile diversity remained
somewhat higher than expected."
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