(WJW) – Extremely rare Jurassic fossils have been found at a lake in the Glen Canyon National Recreation Area in Utah.

A field crew was in the area of Lake Powell in March when it discovered the first tritylodontid bonebed found in the Navajo Sandstone, according to a press release from the National Park Service.

Paleontologists were documenting fossil tracksites when they found the bones and bone fragments of tritylodontid mammaliaforms, early herbivorous mammal relatives from the Early Jurassic, which is about 180 million years ago, the release said.

According to the release, body fossils, including bones and teeth were found, which are in the geologic formation known as the Navajo Sandstone within the Glen Canyon Group.

The fossils are extremely rare and are a very important fossil vertebrate discovery this year, the release said.

According to the National Park Service, the area where the fossils were discovered was covered by Lake Powell due to fluctuating water levels. Paleontologists were “at the right place at the right time right before the annual snowmelt filled the lake,” the release said.

According to the release, several hundred pounds of rocks encased the fossil bones and skeletons found at the site.

The fossils will eventually become part of the Glen Canyon NRA museum collections at the Prehistoric Museum in Price, Utah.