The world's largest sea-dwelling crocodile was recently unearthed in the Tunisian desert. Paleontologists say this massive prehistoric predator would have been more than 30 feet long and likely weighed three tons - the skull alone measured more than five feet long. Researchers have named the new species Machimosaurus rex.

"It's just big. It's almost the size of a bus," Federico Fanti, lead researcher from the University of Bologna in Italy, said in a statement. "It definitely was at the top of the food chain at the time, at least in this particular locality." (Scroll to read more...)

The fossils, including a skull and some other bones, were discovered by Fanti and colleagues with support from the National Geographic Society. Based on the fragmented remains excavated from 120-million-year-old rock at the edge of the Sahara Desert in Tunisia, researchers confirm M. rex is the biggest ocean-dwelling member of the crocodile family tree.

Other than its super-sized body and narrow snout - which researchers say allowed it to swim through the ocean - this prehistoric crocodile would have looked much like its modern-day relatives. Researchers also believe the fossil's massive skull, paired with short, stocky teeth indicate M. rex had "a very incredibly powerful bite force," able to grind the shells of large marine turtles, of which many fossils were found together with the crocodile.

"It would likely have been something of an ambush predator, hanging around in shallow water hunting turtles and fishes and maybe waiting for some land animals to come a little too close to the shore," University of Edinburgh paleontologist Stephen Brusatte, who was not involved with the new study, commented.

However, this discovery lends more to science than just another new species: It is changing the way scientists view the mass extinction that is thought to have occurred at the end of the Jurassic period, 145 million years ago.

M. rex belongs to a group of prehistoric crocodiles that were thought to have gone extinct about 150 million years ago at the end of the Jurassic Period, but the new fossils indicate this particular M. rex  was alive about 130 million years ago. This means they were still alive during the Cretaceous, about 25 million years after the period of "alleged global extinction."

"That's leading us to consider the mass extinction theory is wrong and that we should better understand what's going on at the end of the Jurassic period," Fanti concluded.

Their findings were recently published in the journal Cretaceous Research.

Related Articles 

NASA's CORAL Mission Takes Reef Studies To New Level

Turtle Fossils Shed Light On Rise Of Andes Mountains

Jurassic 10-Armed Squids Were Swift Swimmers, Researchers Say

For more great nature science stories and general news, please visit our sister site, Headlines and Global News (HNGN).

-Follow Samantha on Twitter @Sam_Ashley13