Paleontologists undertook an arduous deep dig in trenches of… a museum in Utah. They found armored lizard bones. Described in a new paper and named Bolg amondol, this newly identified, raccoon-sized lizard lived in the Late Cretaceous period, around 76 million years ago.
This animal is part of the monstersaur (ridiculously cool name! – Ed.) lineage, and inhabited the lush floodplains of what is now southern Utah. Its name, taken from J.R.R. Tolkien’s The Hobbit, means “mound-headed Bolg”
Artist: Cullen Townsend, https://x.com/cullen_townsend/status/1936076817141842270/photo/1
From Museum Jar to Monster
“I opened this jar of bones labeled ‘lizard’ at the Natural History Museum of Utah, and was like, oh wow, there’s a fragmentary skeleton here,” said lead author Dr. Hank Woolley. “We know very little about large-bodied lizards from the Kaiparowits Formation in Grand Staircase-Escalante National Monument in Utah, so I knew this was significant right away.”
The specimen was collected 20 years ago, in 2005. But, its significance only got noticed when Dr. Woolley visited the Utah museum’s research collections. “Although we knew the specimen was significant when it was discovered back in 2005,” said Dr. Irmis, co-author (from the NHM, Utah) “it took a specialist in lizard evolution, like Hank, to truly recognize its scientific importance and take on the task of researching and scientifically describing this new species.”
Photographs (left side of panels) and rendered CT scans (right side of panels) of the right vomer UMNH VP 16266.25 (Bolg amondol) in (A) dorsal, (B) ventral, (C) medial, (D) lateral, (E) anterior and (F) posterior views. (G) Inferred placement of the element in a schematic reconstruction of the skull of Bolg amondol, modified from the ventral view of Gobiderma pulchrum. Anatomical abbreviations: art, articular surface; frm, foramen; mdl, medial lamina; mdm, medial margin; t, trough; vc, ventral crest. Image Credit: Dr. Hank Woolley et al
Most species names come from Latin, but this one is named in Tolkien’s Elvish language, Sindarin. “Amon” means “mound”, and “dol” means “head” in the Elvish language, a reference to the mound-like osteoderms found on Bolg’s and other monstersaur skulls.
Time to discuss what a monstersaur is
Monstersaurs are lizards characterized by their large size and distinctive features like pitted, polygonal armor attached to their skulls and sharp, spire-like teeth. They have a roughly 100 million-year history, but their fossil record is largely incomplete. This makes the discovery of Bolg a big deal for understanding these lizards.
Bolg would have been a bit of a monster. It was about three feet long, including its tail. So not massive compared to dinosaurs, but if you compare them to modern lizards, it was huge.
This discovery sheds light on a lesser-understood lineage of big-bodied lizards coexisting with dinosaurs. Dr. Irmis describes Bolg’s habitat as a stable, productive ecosystem, teeming with reptilian diversity. Multiple large predatory lizards, each exploiting different prey and microhabitats, roamed these prehistoric floodplains.
The fossil’s late recognition underlines how much paleontology still relies on revisiting museum collections with fresh expertise.