Scientists say the fossils of an ancient "swamp monster" that roamed the wilds of West Texas are those of a new species.

Two crocodile-like reptiles called phytosaurs died about 205 million years ago in an oxbow lake, where they were entombed for centuries.

With its 2-foot-long (0.6-meter-long) snout, Machaeroprosopus lottorum would have resembled—and acted like—a modern-day gharial, ambushing prey such as fish and amphibians from beneath the water.

Paleontologists dubbed the ancient creature M. lottorum after the Lott family, which owns the Texas Panhandle ranch where the two skulls were discovered in the summer of 2001. The first skull the scientists found wasn't well preserved, but a few weeks later, when Doug Cunningham, a field research assistant at the Museum of Texas Tech University and co-author of the study, dug up the second skull, they were shocked.

"We were all kind of in awe of it," Cunningham said in a statement. "It had this long, skinny snout. It was quite a bit different" from the skulls of known phytosaurs.

The odd-looking skull prompted the researchers to launch a lengthy effort to formally describe it as a new species. Now that it has been, scientists suspect there may be more species of Triassic phytosaurs than was previously thought.

Swamp Thing

When other paleontologists began studying the skulls, says study co-author Bill Mueller, assistant curator of paleontology at the museum, they noticed something that suggested these phytosaurs were a new species: An opening at the top of the skull, called the supratemporal fenestra, was located in a different place than on known phytosaurs.

The scientists think the two skulls represent a male and a female. One of the skulls sports a bony crest that stretches from nostril to beak tip. Many paleontologists believe these were female-attracting features found only on male animals. The other skull did not have such a crest, according to the scientists, whose study was published in the journal Earth and Environmental Science Transactions of the Royal Society of Edinburgh.

Andy Heckert, a phytosaur expert and geologist at Appalachian State University, Boone, North Carolina, who wasn't involved in the study, agreed with the theory that males had a bony crest, and that the skulls represent different sexes.

However, much of what's assumed about phytosaurs is speculation, as only a few skeletons have ever been found. If paleontologists could find an intact one, they could confirm if it really was a swamp-dweller by measuring its legs: Short, squat limbs would mean it lived in water. (Learn about sea monsters in National Geographic.)

Their wish may be granted: Study co-author Mueller said his team just found a huge phytosaur skull that's now being excavated.