Millions of years ago, giant pygmy crocodiles roamed parts of Africa with a fondness for our human ancestors.
In a new study, researchers led by the University of Iowa have announced the discovery of two new species of crocodiles that roamed East Africa 18 to 15 million years ago before mysteriously disappearing. The species, called giant pygmy crocodiles, are related to the pygmy crocodiles currently found in central and western Africa.
But the giant pygmy crocodiles were much larger – hence their name – than their modern cousins. Dwarf crocodiles rarely exceed 4 or 5 feet in length, but ancient forms measured up to 12 feet and were probably among the most formidable threats to any animal they encountered.
“They were the largest predators our ancestors faced,” says Christopher Brochu, a professor in the Iowa Department of Earth and Environmental Sciences and corresponding author of the study. “They were opportunistic predators, just like crocodiles are today. It would have been downright dangerous for old people to go to the river for a drink. »
The new species are called Kinyang mabokoensis and Kinyang Chernovi. They had short, deep snouts and large conical teeth. Their nostrils opened slightly up and forward, not straight up like modern crocodilians. They spent most of their time in the forest rather than in the water, waiting to ambush prey.
“They had something like this big smile that made them really happy, but they would bite your face off if you gave them the chance,” Brochu said.
Kinyang lived in the Rift Valley of East Africa, in parts of present-day Kenya, during the early-middle Miocene—a time when the region was mostly forest-covered. However, from the end of what has been called the Miocene climate optimum about 15 million years ago, both species seemed to disappear.
Why are they gone? Brochu believes that climate change has led to less rainfall in the region. Reduced rainfall has led to a gradual retreat of forests, giving way to grasslands and forested mixed savannas. The landscape change has had an impact Kinyangthe researchers say they likely prefer forested areas for hunting and nesting.
“Modern pygmy crocodiles are found exclusively in forested wetlands,” says Brochu, who has studied ancient and modern crocodiles for more than three decades. “Habitat loss may have caused a major change in the crocodiles in the area.
“The same environmental changes have been linked to the rise of large, bipedal primates that gave rise to modern humans,” adds Brochu.
Brochu realizes what caused this Kinyang Dying off requires additional testing because researchers can’t pinpoint exactly when the animals became extinct. Also, there is a gap in the fossil record in between Kinyang and other lineages of crocodiles that appeared about 7 million years ago. Among the new arrivals were relatives of the Nile crocodile currently found in Kenya.
Brochu has examined the specimens on several visits to the National Museums of Kenya, Nairobi, since 2007.
The research was funded by the US National Science Foundation, the National Geographic Society, the Leakey Foundation, the Wenner Gren Foundation for Anthropological Research, the Fulbright Collaborative Research Program, the University of Oxford’s Boise Fund, and the IUCN Specialist Group of Crocodiles, the University of Iowa, the Karl and Marie Schack Foundation and the Association of Friends and Sponsors of the Goethe University Frankfurt and the Ministerio de Universidades de España.
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Materials provided by University of Iowa. Originally written by Richard C Lewis. Note: Content can be edited for style and length.