Unlabeled fossils — a jawbone, some teeth and armored plates — have been identified as those of a 30-foot-long crocodile, the largest that ever lived in prehistoric New Mexico.

The fossils of the predator had been stored, unclassified, for six years among the 100,000 fossils at the New Mexico Museum of Natural History and Science here.

"It just got sort of stuck in the collection, and nobody noticed it," paleontology curator Spencer Lucas said.

The plump-looking armored plates intrigued Lucas, because crocodile plates typically are thin and flat. He investigated and determined its pedigree: the first deinosuchus from New Mexico.

"This is the biggest crocodile that ever lived in New Mexico," Lucas said. "Its contemporaries living at the same time were about half its size."

Paul Sealey, a volunteer researcher and collector, found the deinosuchus near Farmington in 1999. Sealey said he thought the fossil belonged to some kind of crocodile, but said he didn't know of any deinosuchus in New Mexico.

The crocodile will be moved onto the floor of the museum's atrium in February or March, said museum spokesman Tim Aydelott.

It will be on display along with an artist's sketch of how it looked in life, he said.

Finding the species in New Mexico can tell paleontologists more about what the general ecosystem of the area was like, Lucas said.

"What we can learn right off is we've got to stop thinking the biggest things in these ecosystems were dinosaurs," Lucas said. "This thing was the same length and maybe the same weight as a tyrannosaur."

The crocodile lived in New Mexico when the state was part of a swampy tropical seashore 75 million years ago. It probably ate young dinosaurs, Lucas said.

"He had a good life," he said. "He did whatever he wanted to do. He probably didn't have any natural predators and terrorized the New Mexico seashore."

Other deinosuchus remains have been found in Texas, North Carolina and Montana, he said.