When crocodiles tried to be mammals: the 100-million-year-old Pakasuchus kapilimai with some very unusual teeth.
Credit: Mark Witton, University of Portsmouth
The Cretaceous croc had specialised teeth that looked suspiciously like the molars that were adapted for grinding food.
Credit: Zina Deretsky, National Science Foundation
PARIS: An ancient, mammal-like crocodile that could chew, something its modern gash-and-gulp cousins cannot do, has been discovered, according to scientists.
The 100-million-year-old reptile, unearthed in Tanzania, was about the size of a domesticated cat and more at home on land than in water.
It had an unusually lean profile, a flexible backbone and relatively little scaly armour around its midriff, the better to leap in the air to grab giant dragonflies and other airborne prey.
Teeth suspiciously like molars
But the most bitingly distinctive feature of Pakasuchus kapilimai, the researchers said, was its choppers.
It shared the overhanging, fang-like canines that today's alligators and crocodiles use to rip into their victims' flesh before swallowing them more-or-less whole.
But it also had specialised teeth that looked suspiciously like the molars - adapted for grinding food rather than slashing it - once thought to be unique to our distant warm-blooded ancestors.
"Trying to be a mammal"
"At first glance, this croc is trying very hard to be a mammal," quipped Patrick O'Connor, a professor at Ohio University in Athens and lead author of the study, published in Nature.
"A number of characteristics of this new species are very similar to features that were critical during the course of mammalian evolution from the Mesozoic into the Cenozoic," which began 65 million years ago, he said in a statement.
The discovery adds to a growing body of evidence suggesting that crocodiles were once far more diverse that they are today in body type, habitat and appetites.
Living with dinosaurs
The diminutive croc would have co-existed with carnivorous theropods such as Tyrannosaurus rex and Velociraptor, as well as the huge, plant-eating Sauropods.
O'Connor and colleagues found a complete skeleton of Pakasuchus in Tanzania's Rukwa Rift Basin in 2008, and have also recovered portions of seven different individuals.
