Utah's rich sandstone yields one new Cretaceous-era dinosaur species after another, but the latest one, a pot-bellied herbivore with a meat-eating ancestry, is so strange it took nearly a decade to properly describe and name it.

A species of therizinosaur , Nothronychus graffami was a waddling bird-beaked, small-headed oddity that opens new insights into dinosaur evolution and diet, according to a study published Wednesday in the journal Proceedings of the Royal Society B: Biological Sciences . The bipedal beast stood 13 feet in height on stumpy legs spread wide off a broad back encasing a massive digestive tract. Its signature feature was foot-long claws tapering off its hands.

"They could have

been for foraging, used as grappling hooks to pull down branches," said the study's lead author Lindsay Zanno, a former University of Utah graduate student now at Chicago's Field Museum. "They could have been used for defense or intimidation. They were pretty slow, lumbering creatures. They don't have horns or armor to protect them."

Zanno's study is based on one of the most complete therizinosaur, a term derived from the Greek therizo meaning "to reap," ever recovered in North America. Scientists stumbled upon it in 2000 near Big Water, Utah. Much of the 92.5-million-year-old skeleton is stored at the Utah Museum of Natural History, while a mounted cast, about 18 feet long, is on display at the Museum of Northern Arizona in Flagstaff. While working on an unrelated plesiosaur excavation a decade ago in marine shale deposits, Big Water resident Merle Graffam picked up a toe bone to show David Gillette, a paleontologist with the Museum of Northern Arizona.

"He said, 'Hey Dave, what's this?'" said Gillette, Utah's former state paleontologist and co-author of the new study. "It was an isolated bone the size of a tangerine. We knew it wasn't from a plesiosaur. It was too small to be a hadrosaur" -- the duck-bill dinosaurs Utah is becoming famous for. "It was a stumper. He took us to the site and sure enough, it led to more bones."

For his contribution, Graffam, a museum volunteer, became the creature's namesake, announced for the first time Wednesday. Gillette's team eventually recovered 80 percent of the creature from the site on Utah State Trust lands. Missing were the skull, neck and some ribs, but still a remarkably complete specimen that closed vexing gaps in the therizinosaur fossil record.

The discovery adds to science's understanding of therizinosaur, a dinosaur belonging to the therapod family, whose members include Tyrannosaurus rex and Velociraptor. The study suggests these famous predators may have evolved from plant-eating ancestors. While N. graffami was a full herbivore, equipped with tiny leaf-shaped teeth, long neck and small head, it has many characteristics associated with predation, such as bipedal stance and short forelimbs, suggesting it served as an evolutionary bridge.

Scientists believe N. graffami gorged itself on massive leaves it "reaped" from coastal mangrove forests. This individual was likely washed out to sea when it perished and was preserved in marine sediments. Ammonite fossils recovered in the same formation helped co-author Alan Titus, a Kanab-based National Park Service paleontologist, date the specimen.