Rendering of Ahshiselsaurus, a new species of theropod dinosaur discovered in the San Juan Basin. Courtesy/NMMNHS

NMMNHS News:

ALBUQUERQUE – A team of researchers, including a pair of paleontologists from the New Mexico Museum of Natural History & Science (NMMNHS), has identified a massive new species of duck-billed dinosaur in the rocks of northwestern New Mexico.

This newly discovered dinosaur, which researchers named Ahshiselsaurus wimani, lived around 75 million years ago and may have weighed more than nine tons.

“Discoveries like this remind us that science truly is a community,” said NMMNHS Executive Director Dr. Anthony Fiorillo, one of the co-authors on the paper. “Our team of researchers spanning five institutions and two countries were able to build upon research that started nearly a century ago and now advances our understanding of what our state looked like during the Late Cretaceous Period.”

The paper identifying the new species was recently published in the Bulletin of the New Mexico Museum of Natural History and Science, a scientific journal managed by the museum. Dr. Fiorillo worked alongside NMMNHS Paleontology Curator Dr. Spencer Lucas, as well as lead author Sebastian Dalman (Montana State University), and co-authors Steven Jasinski (Harrisburg University), Edward Malinzak (Pennsylvania State University), and Martin Kundrát (Pavol Jozef Šafárik University in Slovakia).

“It seems like paleontologists are discovering new dinosaurs in New Mexico every few months,” Dr. Lucas said. “This new hadrosaur just adds to my conviction that there are many, many new dinosaurs still out there waiting to be unearthed!”

Ahshiselsaurus was a hadrosaurid, the family of herbivorous duck-billed dinosaurs that also includes Parasaurolophus and Edmontosaurus. The bones that would be identified as Ahshiselsaurus were uncovered in San Juan County by famed collector John B. Reeside, Jr. in 1916. In 1935, the fossils were classified as belonging to another hadrosaurid called Kritosaurus navajovius. However, this new research identified distinctions between these fossils and all known hadrosaurids, including several key differences in the animal’s skull.

Based on available fossil data, researchers believe Ahshiselsaurus could have grown to more than 35 feet long and weighed around nine tons. Researchers think Ahshiselsaurus lacked the distinctive head crest associated with Parasaurolophus and several other hadrosaurids. With its large body and flat, duckbill-shaped mouth, Ahshiselsaurus was a plant eater that played a key role in New Mexico’s ecosystem during the late Cretaceous, living alongside armored ankylosaurids, horned dinosaurs like Navajoceratops, and Bistahieversor: New Mexico’s feared “Bisti Beast”.

The newly discovered dinosaur was named for the Ah-shi-sle-pah Wilderness in San Juan County, where it was uncovered. This locality has produced several other famed fossil discoveries, including the horned dinosaur Pentaceratops. The research team worked with NMMNHS Exhibit Fabricator Pedro Toledo (Gááłnez) (Diné) to name the new species. 

For more information about the museum’s paleontological research, visit nmnaturalhistory.org/science/sections/paleontology.