US scientists have discovered fossils of the largest known true crocodile, a creature that roamed what is now Kenya between 2 and 4 million years ago.
The illustration shows the comparative sizes of ancient/modern crocodiles and ancient/modern humans (Chris Brochu / University of Iowa)
“It’s the largest known true crocodile,” said Dr. Christopher Brochu, an associate professor of geoscience at the University of Iowa and a lead author of the study published in the May 3 issue of the Journal of Vertebrate Paleontology. “It may have exceeded 27 feet in length. By comparison, the largest recorded Nile crocodile was less than 21 feet, and most are much smaller.”
The new species, called Crocodylus thorbjarnarsoni, resembled its living cousin, the Nile crocodile, but was more massive.
Dr. Brochu recognized the new species from fossils that he examined three years ago at the National Museum of Kenya in Nairobi. Some were found at sites known for important human fossil discoveries.
“It lived alongside our ancestors, and it probably ate them,” Dr. Brochu said. “Although the fossils contain no evidence of human/reptile encounters, crocodiles generally eat whatever they can swallow, and humans of that time period would have stood no more than four feet tall.”
“We don’t actually have fossil human remains with croc bites, but the crocs were bigger than today’s crocodiles, and we were smaller, so there probably wasn’t much biting involved,” Dr. Brochu explained.
“There likely would have been ample opportunity for humans to encounter crocs,” he added. “That’s because early man, along with other animals, would have had to seek water at rivers and lakes where crocodiles lie in wait.”
The new species is named after John Thorbjarnarson, famed crocodile expert and Dr. Brochu’s colleague who died of malaria while in the field several years ago.
“He was a giant in the field, so it only made sense to name a giant after him,” Dr. Brochu said. “I certainly miss him, and I needed to honor him in some way. I couldn’t not do it.”
Among the skills needed for one to discover a new species of crocodile is, apparently, a keen eye. Not that the fossilized crocodile head is small – it took four men to lift it. But other experts had seen the fossil without realizing it was a new species. “The Nairobi collection is “beautiful” and contains many fossils that have been incompletely studied,” Dr. Brochu pointed out. “So many discoveries could yet be made.”
“C. thorbjarnarsoni is not directly related to the present-day Nile crocodile,” Dr. Brochu explained. “This suggests that the Nile crocodile is a fairly young species and not an ancient living fossil, as many people believe. We really don’t know where the Nile crocodile came from, but it only appears after some of these prehistoric giants died out.”
