Jurassic crocodile fossil discovered in Wyoming may be the missing link in croc evolution

TOMIOKA, Japan —An ancient crocodile relative discovered in Wyoming may be the missing link which explains how crocs evolved to hunt while breathing underwater.

An international team of scientists say the primitive creature reached up to 14 feet long and weighed half a ton. Fossil remains point to the giant animal using its powerful jaws packed with two-inch, razor-sharp teeth to drag giant plant-eating dinosaurs to their doom as they drank at the water’s edge.

The new species, named Amphicotylus milesi, belonged to an extinct group of early crocodiles called goniopholidids. Researchers say the fossil is the best-preserved specimen to date. Lead author Dr. Junki Yoshida of Hokkaido University in Japan describes Amphicotyleus as the modern croc’s “uncle fossil.”

“It reveals the origin of their unique breathing system for the first dive,” Dr. Yoshida says in a statement to SWNS. “Amphicotylus milesi has the backward extension of the nose duct and the short and curved tongue bone similar to modern crocodilians.”

“This suggests that, by keeping their external nostrils above the water surface, the crocodilian ancestors could raise the valve at the tongue,” Yoshida adds. “They could breathe underwater while holding prey in the mouth, as modern crocodilians do today.”

Opportunistic eaters

Researchers believe the prehistoric United States resembled the Serengeti of modern-day Africa when Amphicolytus prowled 155 million years ago. Life in this environment, during the late Jurassic period, would need to be able to adapt to harsh droughts and months of monsoon, flooding the rivers.

Study authors believe large dinosaurs migrated like the herds in Africa do today, with Amphicotylus ready to pounce. The scenario is similar to the annual life or death migration of wildebeest across the Serengeti. Crocodiles and big cats lie in wait as the herd of more than one million makes its miles-long trek across the savannas of Tanzania and Kenya.

Goniopholidid
New Goniopholidid. (Credit: Gunma Museum of Natural History / SWNS)

“Amphicotylus gives us a unique window back in time to the evolution of one of the key features that made crocodiles and their relatives one of the Earth’s most successful group of land animals,” says study co-author Dr. Michael Ryan from Carleton University in a release. “It was features such as this that may have helped crocodiles survive the asteroid impact that wiped out all of the non-avian (birds) dinosaurs 66 million years ago at the end of the Cretaceous.”

Study authors say this crocodile relative was an opportunistic predator that likely ate everything from small frogs, lizards, turtles, and fish, to full-size dinosaurs. The almost complete skeleton – along with 30 teeth – were unearthed at a famous dinosaur graveyard called the Morrison Formation.

Crocodiles are the ultimate survivors

Dr. Yoshida notes that goniopholidids have the long, flat snout and secondary palate just like modern crocodilians. Researchers add this is a key feature in their early evolution. Today’s crocodiles are the descendants of a terrestrial ancestor that gave rise to a lineage of successful semi-aquatic predators through the acquisition of a suite of unique characteristics.

“Here, we report a new species, Amphicotylus milesi, with the description from the best-preserved specimen to date from Wyoming,” Dr. Yoshida tells SWNS. “The anatomy sheds light on the acquisition of a new respiratory system and their early aquatic adaptation.”

Crocodiles can hold their breath underwater for up to an hour thanks to their amazing ability to retain oxygen. They are the ultimate survivors, dating back 230 million years. They can easily adapt to different environments, moving on land and in water with surprising speed. Crocodiles grab fish, reptiles, birds, and mammals using a long snout and powerful jaws.

Amphicotylus, described in the journal Royal Society Open Science, disappeared before the extinction of the dinosaurs 66 million years ago. The reason, however, remains unknown.

South West News Service writer Mark Waghorn contributed to this report.

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