The cat-size Pakasuchus kapilimai had relatively long legs and a nose similar to a dog's. And, perhaps weirdest of all, it had mammal-like teeth that gave it a power earlier unknown among reptiles -- ability to chew, they say.
In fact, the 105-million-year-old crocodile, whose fossilised remains were dug up from 105-million-year-old rock by the palaeontologists scouring a river bank in Tanzania, was something of a stand-in for mammals in Gondwana continent.
It enjoyed land-based lifestyle on the African floodplains far removed from its aquatic descendants, preying on dragon flies and other insects and small animals, say the palaeontologists from Ohio University.
After the discovery, they were able to create detailed digital images of its unusual teeth accurate to millionths of a meter using state of the art medical scanners, 'The Daily Telegraph' reported.
"At first glance, this croc is trying very hard to be a mammal. Its head would fit in the palm of your hand. If you only looked at the teeth, you wouldn't think this was a crocodile. You would wonder what kind of strange mammal or mammal-like reptile it is.
"This gives us a number of interesting evolutionary developmental research questions to begin addressing using living crocodiles as models," Prof Patrick O'Connor, who led the team which made the discovery, as saying.
Prof O'Connor said it wasn't as heavily armoured as other crocodiles, except along the tail. This suggests the creature was quite mobile and probably actively foraged on land, unlike water-dwelling crocs.
Other aspects of its anatomy suggest it was a land-dwelling creature that likely feasted on insects and other small animals to survive. The palaeontologists, who have dubbed the animal Pakasuchus kapilimai, found one complete specimen and portions of seven other individuals. Paka is Ki-Swahili for cat in reference to the animal's short, low skull with slicing, molar-like teeth, and souchos is ancient Greek for crocodile.
Prof O'Connor said: "Once we were able to get a close look at the teeth, we knew we had something new and very exciting." The findings have been published in the 'Nature' journal.