Researchers at University of Florida say they've discovered a 16-foot, 900-pound crocodile-like monster that lived 60 million years ago in the world's oldest-known rainforest.

The newly uncovered reptile shared the prehistoric waterways with Titanoboa, the giant 58-foot serpent depicted recently in a Smithsonian Channel documentary.

In a study posted online in the journal Historical Biology, scientists have dubbed the croc species Anthracosuchus balrogus, after the ferocious Balrog, a fictional creature that inhabited a mysterious mine in the novel "The Lord of the Rings" by J.R.R. Tolkien.

Recovered from the same layer of rock in which Titanoboa was found, in northern Colombia's Cerrejon coal mine, the ancient croc opens a new chapter on the apparent adaptability and diversity of tropical crocodyliforms -- which may allow scientists to better understand how crocodiles today are able to adapt to changing environments, said lead author Alex Hastings, a post-doctoral researcher at Martin Luther Universität Halle-Wittenberg and former graduate student at the Florida Museum of Natural History and the university's department of geological sciences, via a news release.

"It quickly became clear that the four fossil specimens were unlike any dyrosaur [ancient croc] species ever found," Hastings said, noting the reptile's' short snout and large jaw muscles would give it an incredibly powerful bite. "Everyone thinks that crocodiles are living fossils that have remained virtually unchanged for the last 250 million years. But what we're finding in the fossil record tells a very different story."

Jonathan Bloch, the study's co-author and associate curator of vertebrate paleontology at the museum, said researchers were "stunned" when they got their first look at the new species.

"We couldn't believe it had such a boxy, short skull and that it was still a dyrosaur," Bloch said. "It really busts the mold for these animals. It is such a completely different looking beast than we've seen for these crocodile-like animals."

The study of fossils in Cerrejon is providing scientists a much fully understanding of the early history of crocodiles in the Neotropics, the region of the New World that stretches southward from the Tropic of Cancer to include southern Mexico, Central and South America and the West Indies, said paleobotanist and study co-author Carlos Jaramillo of the Smithsonian Tropical Research Institute.

"This new finding showcases the wide range of ecological variation that tropical crocodiles already had by 60 million years ago," said Jaramillo.

The recent find is the third new species of ancient croc pulled from Cerrejon, one of the world's largest open-pit coal mines.