Oldest Identified Pachycephalosaur Fossil Found in Mongolia

Meet the Oldest Dome-Headed Dinosaur Ever Found

By Jack Tamisiea edited by Andrea Thompson

Anyone who has ever flipped open a dinosaur guide is probably going aware of pachycephalosaurs. These dome-headed dinos are sometimes depicted ramming the tops of their bowling-ball-like skulls into predators or rivals.

Yet regardless of their reputation, pachycephalosaurs proceed to puzzle paleontologists partly as a result of fossils of those bipedal herbivores are uncommon, says Lindsay Zanno, a paleontologist at North Carolina State University. “The exception is their cranial domes, which were practically indestructible and are usually all we find of these critters,” she says. Almost all of those cranium caps date again to the Late Cretaceous, when pachycephalosaurs had been already established throughout the Northern Hemisphere, obscuring the group’s early evolution.

A pachycephalosaur skeleton that was lately found in Mongolia is poised to lastly fill within the lacking chapter of this dinosaur clade’s early historical past. The remarkably full fossil, which Zanno and her colleagues described on Wednesday within the journal Nature, represents a new species that is the oldest known dome-headed dinosaurs.

On supporting science journalism

If you are having fun with this text, think about supporting our award-winning journalism by subscribing. By buying a subscription you’re serving to to make sure the way forward for impactful tales in regards to the discoveries and concepts shaping our world right now.

The fossil was unearthed in 2019 in Mongolia’s Gobi Desert, a famed hotbed for dinosaur fossils. While surveying a hillside, Mongolian paleontologist Tsogtbaatar Chinzorig of North Carolina State University and a co-author of the brand new paper, found the highest of a dinosaur’s noggin protruding of a cliff.

The fossil was embedded inside rocks that date to between 115 million and 108 million years in the past, within the Early Cretaceous interval, when the realm was coated by a lush river valley. The crew deposited the outstanding discover on the Mongolian Academy of Sciences’ Institute of Paleontology, the place Tsogtbaatar can also be affiliated.

As the researchers chipped away on the surrounding rock, they shortly realized that the brand new specimen represented probably the most full pachycephalosaur fossil ever found. In addition to the rounded cranium, the skeleton incorporates the primary document of a pachycephalosaur hand and an entire tail coated with petrified tendons. It even preserves gastroliths—gizzard stones that the animal swallowed to assist grind plant materials in its digestive tract.

The scientists named the brand new species Zavacephale rinpoche. The species identify is the Tibetan phrase for “precious one” and refers back to the means the cranium resembled a rounded, polished gemstone when Tsogtbaatar found it.

Zavacephale was a pint-sized pachycephalosaur that weighed roughly as a lot as a miniature poodle. Despite its diminutive measurement, the animal possessed a completely developed dome and had doubtless reached sexual maturity.

Researchers have debated for many years how these dinosaurs used their signature dome. Some have argued that the rounded melons performed a job in sexual choice or that they helped species acknowledge each other. But the most well-liked interpretation is that the animals used the construction to headbutt each other, as trendy bighorn sheep do, which is supported by fossilized cranium caps that protect lesions and different indicators of trauma.

The crew concluded that Zavacephale represents the oldest recognized pachycephalosaur and certain originated early on within the evolution of this weird group of dinosaurs. “It tells us that the dome head evolved early in pachycephalosaur evolution and arose long before Zavacephale’s bigger, cousins started littering the latest Cretaceous fossil record with their skull caps,” says Stephen Brusatte, a paleontologist on the University of Edinburgh, who was not concerned within the new examine.

Zavacephale’s skull had just a few noteworthy quirks, nevertheless. It was principally composed of just one cranium bone as a substitute of the 2 bones seen in later species and largely lacked the knobby horns that different pachycephalosaurs had as ornamentation. Brusatte thinks that future finds of early pachycephalosaurs could additional reveal how the group’s signature headgear developed over time.

Zanno agrees. “Zavacephale was just an opening act,” she says, “and now we get to see more of the show.”

It’s Time to Stand Up for Science

If you loved this text, I’d prefer to ask to your assist. Scientific American has served as an advocate for science and business for 180 years, and proper now often is the most important second in that two-century historical past.

I’ve been a Scientific American subscriber since I used to be 12 years outdated, and it helped form the way in which I take a look at the world. SciAm at all times educates and delights me, and conjures up a way of awe for our huge, lovely universe. I hope it does that for you, too.

If you subscribe to Scientific American, you assist make sure that our protection is centered on significant analysis and discovery; that now we have the assets to report on the selections that threaten labs throughout the U.S.; and that we assist each budding and dealing scientists at a time when the worth of science itself too typically goes unrecognized.

In return, you get important information, charming podcasts, good infographics, can’t-miss newsletters, must-watch movies, difficult video games, and the science world’s greatest writing and reporting. You may even present somebody a subscription.

There has by no means been a extra necessary time for us to face up and present why science issues. I hope you’ll assist us in that mission.