Armoured monstersaur lizard species from the dinosaur era discovered in Utah

Artistic depiction of Bolg amondol raiding an oviraptorosaur nest in the dense, prehistoric landscape of the Kaiparowits Formation. (Image: Art by Cullen Townsend)

An unexpected fossil find in a museum drawer has unveiled a new species of lizard with a name fit for Tolkien’s universe, offering clues to a hidden world of ancient monsters.

A Lizard Fit for Middle-Earth

A raccoon-sized lizard with bony armour has been discovered in southern Utah. Named Bolg amondol, the new species hails from the Kaiparowits Formation in Grand Staircase-Escalante National Monument. This ancient predator was part of the monstersaur lineage, close cousins of today’s Gila monsters. The discovery was made by Dr Hank Woolley of the Natural History Museum of Los Angeles County, who first spotted the fossil while examining a labelled jar in a museum collection.

The creature takes its name from the goblin prince Bolg in J.R.R. Tolkien’s The Hobbit. Its second name, amondol, comes from the fictional Elvish language, meaning “mound-headed” — a nod to the lizard’s skull armour. The find reveals that monstersaurs once roamed lush forests of Late Cretaceous North America, hunting small prey and defending themselves with spiked teeth and rough skin.

From Shelves to Science

Though the fossil was first unearthed in 2005, its scientific importance wasn’t fully realised until Woolley studied it in detail. The lizard’s skeleton is incomplete but represents one individual, with preserved skull fragments, vertebrae, limbs and bony armour known as osteoderms. These remains have helped researchers place Bolg within the tree of life, shedding light on a poorly known group of large-bodied lizards.

Co-author Dr Randy Irmis of the University of Utah says the find highlights the value of museum collections. Many fossils remain unstudied for years until experts revisit them. With further analysis, the team confirmed that Utah’s ancient forests supported at least three types of large, meat-eating lizards — a rare glimpse into lesser-known parts of dinosaur ecosystems.

A Lizard on the Move

The discovery also connects continents. Bolg’s closest known relative lived in Asia’s Gobi Desert, suggesting long-distance travel between ancient landmasses. The Late Cretaceous period saw many creatures migrating across what was then a connected world. This lizard’s presence in Utah hints that even smaller reptiles followed those same paths.

Dr Joe Sertich of the Smithsonian Tropical Research Institute says big lizards like Bolg likely filled important roles in ancient food chains. They may have preyed on dinosaur eggs and small animals, much like modern monitor lizards.

Supporting Future Discoveries

The research was published in Royal Society Open Science and supported by the Bureau of Land Management, the National Science Foundation and the Dinosaur Institute. Dr Woolley began the project as a PhD student and has continued it as a postdoctoral fellow. His work shows the importance of supporting early-career scientists.

Co-author Dr Nathan Smith of the Dinosaur Institute says the find reflects the museum’s mission to mentor young researchers. The Kaiparowits Formation, where Bolg was found, has become one of North America’s richest fossil beds. Its ancient rocks have already yielded dozens of dinosaur species and continue to offer new surprises.

Researchers say this latest discovery reminds us why protecting public lands matters. These preserved spaces are not just scenic landscapes — they hold the stories of life that came long before us.