The 125-million-year-old herbivore Hippodraco scutodens—whose partial skull and skeleton were unearthed in 2004 in eastern Utah—has a long, low skull like a horse's and a mouth filled with shield-shaped teeth.

Also revealed recently, fossils of another newly described species from the same time period, Iguanacolossus fortis, were found in 2005 not far from Hippodraco. (Take a dinosaur quiz.)

That "ponderous beast" is named for its relatively large size—about 30 feet (9 meters) long, compared with Hippodraco's 15 feet (4.5 meters), according to the study.

(Related: "'Amazing' Dinosaur Trove Discovered in Utah.")

Both of the newfound dinosaurs are iguanodonts, an "extremely successful" group of plant-eaters that expanded worldwide during the