This 30-foot-long supercrocodile - packing a snout full of jagged 5-inch teeth - rivaled a Tyrannosaurus rex when it cruised prehistoric waterways, snacking on 10-foot sturgeons and devouring large land-dwelling dinosaurs that ventured near the shores for a drink.
"The fish were like a sushi appetizer to tide it over before the steak," said Alan Titus, paleontologist for the Grand Staircase-Escalante National Monument. "It was just as big as Tyrannosaurus but lived in water."
At an announcement Friday, Titus said he discovered about a quarter of the creature's upper snout in the fossil-rich area of the Kaiparowits Plateau in Kane County in late June.
He said preliminary inspection indicates that not only does the 75.5-million-year-old fossil fragment represent a new species, it also may require a whole new genus to categorize it.
"It is the biggest crocodile fossil ever found in Utah," Titus said. "People have found teeth of crocodiles before, so we knew they were out there, but nothing this big. This is a super-duper fossil."
The discovery marks the latest addition to the fossil menagerie unearthed on the monument's Kaiparowits Plateau. It was removed by Titus with the help of two graduate students.
Titus and one of the students plan to write a paper on the find and submit it for peer review and publication.
Titus said the croc's size is evident from fossilized sockets 1.75 inches in diameter that once sprouted the ferocious teeth, which have long since disappeared. The animal's skull probably reached 4 feet in length.
The teeth's position and the jaw's shape, he added, suggest the croc is something never before identified. It does not fit into the two known genuses for prehistoric crocodiles.
Grad students Laura Bordelon, working on a master's in biogeology at the University of Southern Illinois, and Michael Kanell, working on a doctorate in geology at the University of Montana, helped Titus remove the fossil.
It wasn't easy.
"The rock was like concrete and required cutting with a rock saw," Bordelon said. "It probably weighed 250 pounds [once encased in plaster] and took three days to get out."
Said Kanell, who will assist Titus on the paper: "It was ginormous."
Bordelon and Kanell have been cleaning sand from the fragile fossil and stabilizing it with injections of glue at the monument's paleontology lab in Kanab. Eventually, the fossil will be sent to the Utah Museum of Natural History in Salt Lake City for further study.
Titus said the fossil was found in a part of the Kaiparowits that already has yielded new species of horned dinosaurs, plant-eating hadrosaurs and a bizarre birdlike species called a hagryphus.
The supercroc, he said, is "another piece of the puzzle we're putting together here."
* What was found: About a quarter of the roof of upper snout
* Where it was found: In southern Utah's Kane County
* When it was found: Late June
* When it lived: 75.5 million years ago
* Its size: 30 feet long
* Its teeth: About five inches; used for tearing
* Its habitat: Freshwater tributaries
* Its classification: Does not conform to a known genus or species