Fossils from BLM lands help confirm a new species of Allosaur

On Friday, January 24, the BLM participated in the Natural History Museum of Utah's unveiling of Allosaurus jimmadseni, a new species of Allosaur. Paleontologists unearthed the first specimens in the early 1990s, first in Dinosaur National Monument in northeastern Utah, and later on BLM-administered public land in Wyoming. The huge carnivore inhabited the flood plains of western North America during the Late Jurassic Period, between 157-152 million years ago, making it the geologically oldest species of Allosaurus, predating the well-known state fossil of Utah, Allosaurus fragilis.

Allosaurus jimmadseni was a two-legged carnivore with long forelimbs and sharp recurved claws that were likely used for grasping prey. The new species is named in honor of Jim Madsen, Jr. the late Utah State Paleontologist who excavated and studied tens of thousands of Allosaurus bones from the BLM's Cleveland-Lloyd Dinosaur Quarry in central Utah and contributed greatly to our knowledge of dinosaurs. 

New dinosaur displayed at Natural History Museum in Salt Lake City
The fossil on display with comparison fossils at the Natural History Museum of Utah during the announcement on Friday, January 24, 2020.

The comparisons used to identify the new dinosaur were made with the thousands of bones of Allosaurus fragilis collected from Cleveland-Lloyd Dinosaur Quarry administered by BLM that are housed in the collections of the Natural History Museum of Utah. The Cleveland-Lloyd Dinosaur Quarry is a part of the BLM's new Jurassic National Monument which was designated in the John D. Dingell, Jr. Conservation, Management, and Recreation Act in March of 2019. The monument contains the densest concentration of Jurassic-aged dinosaur bones ever found. Over 12,000 bones belonging to at least 74 individual dinosaurs have been collected at the quarry.

Paleontologist poses with GSENM Poster
Scott Foss, BLM Senior Paleontologist, holding the new BLM Paleontology Poster, which was presented to the staff of the Natural History Museum of Utah.

This discovery highlights the remarkable opportunities for exploration, learning, and scientific inquiry that public lands provide. The BLM is grateful for our partnerships with the National Park Service, Natural History Museum of Utah, and other organizations working to answer natural mysteries. The announcement coincides with the release of the BLM's new paleontology vintage poster (Click here to view the poster.) and Dinofest, an event held at the Natural History Museum of Utah where over 4,000 people learned from paleontology experts from BLM Utah, Dinosaur National Monument, the State of Utah, and professional and amateur organizations devoted to the science of paleontology.

BLM Staff at Dinofest
BLM Utah staff at Dinofest at the Natural History Museum.

The article was published in Peerj, an open-access journal and can be downloaded for free at the following link: The new poster which was unveiled at Dinofest is linked in this article.

Rachel Wootton, Public Affairs Specialist