Scientists identify new crocodile species from the age of ‘Lucy’
Crocodylus lucivenator was the size of a small car
Reconstruction of Crocodylus lucivenator with Australopithecus afarensis by Tyler Stone/University of Iowa
More than 3 million years ago, when our ancient human ancestors — embodied by the iconic “Lucy” — were roaming the African landscape, they would have feared a big, bad crocodile with a prominent lump on its head, patiently lurking in rivers and lakes to attack them.
Crocodylus lucivenator, or “Lucy’s hunter,” was the size of a small car, weighing between 600 and 1,300 pounds with a length of 12 to 15 feet. Its fossils were found in the Hadar Formation, the same rock layers that yielded Lucy, Australopithecus afarensis, one of the most notable fossils in human evolution.
“It was the largest predator in that ecosystem, more so than lions and hyenas, and the biggest threat to our ancestors who lived there during that time,” said Christopher Brochu, professor at the University of Iowa and lead researcher. “It’s a near certainty that this crocodile would have hunted Lucy’s species. Whether a particular crocodile tried to grab Lucy, we’ll never know, but it would have seen Lucy’s kind and thought, ‘Dinner.’”
Brochu has studied ancient crocodiles for 35 years and was the first to look at the Crocodylus lucivenator specimens when he visited a museum in the Ethiopian capital Addis Ababa in 2016.
“I worked with Brochu to provide all the contextual information from the specimens as well as the paleoenvironmental settings for the specimens,” said Christopher Campisano, a research scientist at the Institute of Human Origins and associate professor at the School of Human Evolution and Social Change.
“This find is important for those interested in understanding the relationships amongst fossil and modern crocodiles in Africa. It is also the only known croc at Hadar, while at places like Lake Turkana, they had three to four different species of crocodile.”
C. lucivenator was a dominant creature and the only crocodile on the landscape, an expanse of shrubland and wetlands pocked with rivers lined with trees. Scientists also explained it was an ambush predator, silently submerged in the water, poised to spring on those who came around for a drink.
Notable among the crocodile’s peculiar physical traits was the large hump in the middle of its snout, similar to what is found on the American crocodile but not seen with the Nile crocodile in Africa. The researchers think the hump was used by the male crocodiles to attract a mate.
“You see this in some modern crocodiles,” Brochu said. “The male will lower his head down a little bit to a female to show it off.”
Lucy’s hunter also had a snout that extended further from its nostrils than other crocodiles at that time, and that more closely resembles the lengthened snout in modern crocodiles.
The scientists examined 121 cataloged remains — primarily skulls, teeth and parts of jaws — representing dozens of individuals. The fossils were excavated from the Hadar site in the Afar region of Ethiopia. For decades the region has produced bountiful finds linking humanity’s ancestral past, including Lucy, and was designated a UNESCO World Heritage Site in 1980.
While most fossils were fragments requiring the researchers to extrapolate the full skeleton, one specimen had several partially healed injuries on its jaw that suggested it had tussled with one of its peers, according to Stephanie Drumheller, a teaching associate professor at the University of Tennessee.
“The fossil record preserves similar injuries in extinct groups as well, so this kind of face-biting behavior can be found throughout the crocodile family tree,” Drumheller said. “We can’t know which combatant came out on top of that fight, but the healing tells us that, winner or loser, this animal survived the encounter.”
While there were at least three other crocodile species just south in the region, known as the Eastern Rift Valley, the Lucy’s hunter crocodile appeared to have its territory in Hadar to itself.
“During the Pliocene, Hadar was composed of a variety of habitats alongside its lake and river systems over space and time, including open and closed woodlands, gallery forests, wet grasslands and shrublands,” Campisano said. “Interestingly, this crocodile was one of only a few species that was able to persist throughout.”
The article detailing the research, “Lucy's Peril: A Pliocene Crocodile from the Hadar Formation, Northeastern Ethiopia,” was published in the Journal of Systematic Palaeontology.
This article was adapted from the University of Iowa.