A terrifying 14-feet-long reptile that roamed the Serengeti-like landscape of Wyoming 155 million years ago was the ‘uncle’ of all modern crocodiles.
This is the conclusion of a team of researchers led from Hokkaido University, who have identified a new species belonging to the croc-like ‘goniopholidid’ family.
The fossil of ‘Amphicotyleus milesi’ was unearthed in the East Camarasaurus Quarry — named after the dinosaur finds from the site — in Wyoming’s Albany County.
According to the palaeontologists, in life A. milesi would have weighed in at nearly half-a-ton and sported a mouth packed with 30 two-inch-long razor-sharp teeth.

A 14-foot-long, terrifying reptile roamed Wyoming’s Serengeti-like landscape 155 millions years ago. It was known as the “uncle” of modern crocodiles. Pictured: an artist’s impression of Amphicotyleus milesi menacing a larger camarasaurus at a watering hole

The conclusion is that a group of scientists from Hokkaido University have discovered a new species of the croclike ‘goniopholidids’ family. Pictured: the fossil
According to paper author and palaeontologist Junki Yoshida of Japan’s Hokkaido University, A. milesi was not only the ‘uncle’ of modern crocs — it also revealed the origin of their unique breathing system that they use for diving.
‘Amphicotylus milesi has the backward extension of the nose duct and the short and curved tongue bone similar to modern crocodilians,’ he explained.
‘This suggests that, by keeping their external nostrils above the water surface, the crocodilian ancestors could raise the valve at the tongue.
‘They could breathe underwater while holding prey in the mouth, as modern crocodilians do today.
‘Amphicotylus provides a novel insight into the aquatic adaptation toward modern crocodylians,’ the expert concluded.
Modern crocodiles are capable of holding their breath for up to an hour underwater.
Today there are just 25 species of crocodile still alive, but this number would have been in the hundreds during the time of the dinosaurs, with some reaching up to 30 feet in length and weighing in at three tons — six times that of A. milesi.

According to the Palaeontologists A.milei was nearly half-a-ton, and had 30 2 inch-long sharp teeth. Pictured: photographic and illustrated representations of A. milesi’s skull from various perspectives
At the time A. milesi lived, during the Late Jurassic, what are today the badlands of Wyoming would have been more like the Serengeti of Africa.
Creatures living in this setting would have had to adapt to long periods of severe drought — followed by months of monsoon that would have flooded local rivers.
The researchers believe that A. milesi would have been an opportunistic predator — eating everything from small fish frogs, lizards and turtles up to perhaps even herbivorous dinosaurs and pterosaurs.
Royal Society Open Science has published all of the findings.