The largest known crocodile was big enough to swallow a human being and likely terrorized our ancestors two to four million years ago.
Remains of the enormous horned croc, named Crocodylus thorbjarnarsoni, were unearthed in East Africa. The impressive aquatic reptile exceeded 27 feet long and is described in the latest Journal of Vertebrate Paleontology.
The croc was the dominant predator of its ecosystem, so there is little doubt that it preyed upon our distant ancestors, especially since remains of Australopithecus(a now-extinct genus of hominids) were found nearby.
These relatively tiny individuals would have had no choice but to enter the crocodile's territory for much needed water.
"Humans might have eaten food along a lakeside or riverbank, but more importantly, they would have needed water to drink," lead author Christopher Brochu told Discovery News. "This would have brought them right to where the crocodiles might have been living."
"Crocodiles today like to creep up on animals at the water's edge and grab them before the crocodile is detected," added Brochu, an associate professor of geoscience at the University of Iowa.
He and colleague Glenn Storrs, curator of vertebrate paleontology at the Cincinnati Museum Center, recognized the new species from fossils stored at the National Museum of Kenya in Nairobi. The human remains also found nearby show that our ancestors then only stood about 4 feet tall, so the crocodile could have easily swallowed one whole.
The animal looked similar to a modern Nile crocodile, except with a large snout and a pair of horn-like protuberances behind its eyes.
Storrs also said the croc had a "powerful tail that propelled the animal forward in a desperate 'all or nothing' lunge."
Given the anatomical similarities to today's Nile crocs, Brochu said this prehistoric species would have had a "lifestyle that was probably similar to that of their living counterparts -- semi-aquatic ambush predators that would stealthily approach prey. Anything in the shallow water or close to the waterline would have been in range."
Even in its present de-fleshed state, the crocodile is something to behold. It requires four men just to lift the animal's skull. The species was named after famed crocodile expert John Thorbjarnarson, who worked with Brochu before contracting malaria in the field and dying from the disease.
Brochu and his colleagues previously discovered another man-eating horned crocodile from Tanzania named Crocodylus anthropophagus. This animal was related to C. thorbjarnarsoni, with both distantly but not directly related to today's Nile crocodile.
Evon Hekkala, a crocodile expert who is an assistant professor of biological sciences at Fordham University, told Discovery News that she agrees with the new findings.
The discoveries remind that our human relatives often functioned as prey as well as predators.
In addition to probably being worried about crocodile attacks, these individuals "would have needed to be equally as wary of large carnivorous mammals, such as lion-like felids," Storrs said.
Kenya was a hot spot for early human evolution. Aside from the australopithecine hominids, Storrs said several early species of homo sapiens are known from fossils that are contemporaneous to those of the big and mighty new crocodile.