The Bureau of Land Management in Utah has announced the discovery of a major new cache of very well-preserved dinosaur bones dating back to 4,400 years ago.

Oops! Did I say “4,400?” That was just a guess. The real age is closer to 150 million years old.

SALT LAKE CITY — A newly discovered batch of well-preserved dinosaur bones, petrified trees and even freshwater clams in southeastern Utah could provide new clues about life in the region some 150 million years ago.

The Bureau of Land Management announced the find Monday, calling the quarry near Hanksville “a major dinosaur fossil discovery.”

An excavation revealed at least four sauropods, which are long-necked, long-tailed plant-eating dinosaurs, and two carnivorous ones, according to the bureau. It may have also uncovered an herbivorous stegosaurus.

Animal burrows and petrified tree trunks 6 feet in diameter were found nearby. The site doesn’t contain any new species but offers scientists the chance to learn more about the ecology of that time, said Scott Foss, a BLM paleontologist.

The fossilized dinosaurs are from the same late Jurassic period as those at Dinosaur National Monument, which straddles the Utah-Colorado state line, and the Cleveland-Lloyd quarry near Price.