earth sciences

Laramidia: New Mexico

Reconstructing dinosaur ecosystems from the Fruitland and Kirtland formations of New Mexico

The San Juan Basin of northwestern New Mexico has been known as a dinosaur hot spot for over a century, attracting paleontologists from around the world to its spectacular badland deposits dating to the Late Cretaceous. In particular, the sandstones and mudstones of the upper Fruitland and Kirtland formations preserve multiple dinosaur ecosystems. These have been divided into two separate groups, one dated at about 74.5–74 million years, with some well-known dinosaurs including the large ceratopsian Pentaceratops sternbergii and the crested duck-billed dinosaur Parasaurolophus cyrtocristatus. The younger fauna, from the upper Kirtland, is dated around 73 million years and includes Parasaurolophus tubicen and the tyrannosaurid Bistahieversor. However, the overall ecosystems (geology, plants, invertebrates, small vertebrates), along with many of the small dinosaurs, remain poorly understood. Led by Denver Museum of Nature & Science curator of dinosaurs Joe Sertich, a highly collaborative team of paleontologists, volunteers, and students has been exploring the badlands of northwestern New Mexico each spring since 2014. With a broad focus, the teams have explored the Upper Cretaceous Fruitland and Kirtland formations for evidence of past ecosystems, including the remains of dinosaurs, microvertebrates, fossil plants, fossil wood, and geologic evidence linked to the southern portion of the western landmass of Laramidia.

Collaborating Scientists and Students

Our research in the San Juan Basin of New Mexico is highly collaborative, conducted in partnership with the Bureau of Land Management, which manages permits and access to localities. Another researcher on the project is Lisa Boucher, PhD (University of Texas at Austin), who works on fossil floras and the abundant petrified wood preserved in the region. Students working on the fossils from the area include PhD student C. Hank Woolley (University of Southern California), currently studying fossil lizards collected from the Fruitland and Kirtland formations as part of a broader investigation of patterns of squamate distributions in Laramidia.

New Discoveries

The Denver Museum of Nature & Science team has discovered many partial skeletons of dinosaur and other prehistoric animals from the region, including:

  • Several partial skulls of the horned dinosaur Pentaceratops
  • A beautifully preserved partial skull of the crested duck-billed dinosaur Parasaurolophus cyrtocristatus
  • A partial skull of the tyrannosaur Bistahieversor, an early relative of the younger Tyrannosaurus rex
  • A partial skull of a new species of a nodosaur, a tank-like armored dinosaur
  • An associated skeleton of a new species of small carnivorous dinosaur


Joseph Sertich, PhD

Associate Curator of Dinosaurs

Natalie Toth, MS

Chief Preparator

Salvador Bastien

Fossil Preparator

Tyler R. Lyson, PhD

Associate Curator of Vertebrate Paleontology

Kristen A. MacKenzie, MS

Earth Sciences Collections Manager

Libby Couch

Business Support Specialist

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