Back in 2005, the remains of an animal were found in Grand Staircase-Escalante National Monument, a vast and rugged landscape in southern Utah, USA. They were put into storage at the Natural History Museum of Utah, where they remained for almost 20 years.
It wasn’t until a recent collections survey at the museum that the bones re-emerged, and palaeontologists realised they had been hiding a big secret: they belonged to a giant goblin-like lizard that had never been documented before.
Named Bolg amondol, this newly described lizard was part of a group of large-bodied, armoured reptiles known as monstersaurs – relatives of today’s Gila monsters.
About the size of a raccoon, Bolg amondol was one of several predatory lizards thriving around 76 million years ago in what was then a lush, floodplain ecosystem.
The discovery is not just exciting for its strange appearance; it also suggests that a much greater diversity of large lizards lived alongside dinosaurs in North America’s Late Cretaceous period than previously believed.
Researchers from the Dinosaur Institute at the Natural History Museum of Los Angeles County and the Natural History Museum of Utah led the study, published in the journal Royal Society Open Science.
Finding a goblin
“I opened this jar of bones labelled ‘lizard’ at the Natural History Museum of Utah, and was like, oh wow, there's a fragmentary skeleton here,” says lead author Hank Woolley, who stumbled across the remains while studying the museum collections.
Woolley quickly recognised the importance of the find. Large lizards from the Kaiparowits Formation – a fossil-rich layer of rock within the Grand Staircase-Escalante National Monument – are rare and not well understood. Yet, over the past 25 years, this area has been yielding some of the most spectacular dinosaur-dominated records in North America.
Where did the name come from?
The lizard’s name, Bolg amondol, was inspired by J.R.R. Tolkien’s Lord of the Rings fantasy world. 'Bolg’ refers to a goblin prince in The Hobbit, while ‘amondol’ combines Tolkien’s Sindarin Elvish words 'Amon' (meaning 'mound') and 'dol' ('head') – a nod to the bony, helmet-like armour on its skull.
“Bolg is a great sounding name,” says Woolley. “I think of these lizards as goblin-like, especially looking at their skulls.”
What was Bolg amondol?
Bolg's impressive headgear is just one of several physical traits that place the species in the monstersauria clade – a group known for their spiny teeth and tough, bumpy skin.
Though monstersaurs have been around for nearly 100 million years, their fossil record is patchy, says Woolley. That makes Bolg’s discovery an important piece of the puzzle when it comes to understanding how these lizards evolved and spread across ancient continents.
Measuring up to a metre in length, Bolg would have been a fearsome sight – perhaps hunting small mammals, insects or even baby dinosaurs. It would have been roughly the same size as today’s savannah monitor, a large, muscular lizard from Africa, explains Woolley. “So, by modern lizard standards they’re a very large animal – something that you wouldn’t want to mess around with.”
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Why is the discovery important?
Fossils of Bolg include parts of the skull, limbs, vertebrae and bony armour – enough for researchers to compare it to other known lizards and determine its evolutionary relationships. These remains also help paint a clearer picture of the environment it lived in: a diverse and productive sub-tropical floodplain that supported a variety of predators.
“Discovering a new species of lizard that is an ancestor of modern Gila monsters is pretty cool,” says co-author Randy Irmis, curator of palaeontology at the Natural History Museum of Utah, “but what's particularly exciting is what it tells us about the unique 76-million-year-old ecosystem it lived in.
“The fact that Bolg co-existed with several other large lizard species indicates that this was a stable and productive ecosystem where these animals were taking advantage of a wide variety of prey and different micro-habitats.”
Another remarkable aspect of the find is that it came from fossils that had been sitting in museum storage since 2005. The significance of the bones went unnoticed until Woolley, an expert in lizard evolution, took a closer look. This highlights the potential for further discoveries hiding in museum drawers, says Irmis.
“Although we knew the specimen was significant when it was discovered back in 2005, it took a specialist in lizard evolution like Hank to truly recognise its scientific importance.”
Bolg’s closest known relative comes from Asia’s Gobi Desert, showing that not just dinosaurs, but also smaller reptiles, moved between continents during the Late Cretaceous. This suggests different animal groups shared migration routes across the ancient landmass of Laramidia.
Finally, the discovery underlines the immense scientific value of protecting public lands. The Grand Staircase-Escalante National Monument has been a goldmine for dinosaur-era discoveries, says co-author Joe Sertich of the Smithsonian Tropical Research Institute.
“The exceptional record of big lizards from Grand Staircase-Escalante National Monument may prove to be a normal part of dinosaur-dominated ecosystems from North America, filling key roles as smaller predators hunting down eggs and small animals in the forests of Laramidia.”
For palaeontologists and fantasy fans alike, Bolg amondol is a fascinating glimpse into a time when goblin-like creatures really did walk the Earth.
Main image: Artistic reconstruction of Bolg amondol, depicted raiding an oviraptorosaur dinosaur nest amidst the lush Kaiparowits Formation habitat. Credit: Cullen Townsend
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