Oldest and Most Complete Dome-Headed Dinosaur Discovered in Mongolia

Pachycephalosaurus wyomingensis, dome-headed dinosaur. Credit: DataBase Center for Life Science (DBCLS) / Wikimedia Commons / CC BY 4.0

A remarkably preserved fossil recovered successful Mongolia has revealed the oldest and astir implicit dome-headed dinosaur ever discovered, offering caller penetration into the aboriginal improvement of this uncommon radical of plant-eating species.

The specimen, named Zavacephale rinpoche, lived astir 108 cardinal years agone and represents the earliest known illustration of dinosaurs with thick, rounded skulls—traits that aboriginal defined the dome-headed lineage.

Described successful the journal Nature, the fossil contains acold much than conscionable a skull dome, which is typically each that survives from this group.

In this case, researchers uncovered a astir implicit skeleton, including limbs, hips, shoulders, a reinforced tail, and—for the archetypal clip successful immoderate taxon of this kind—preserved digit bones.

The find enables scientists to recognize however the unsocial assemblage operation of these dinosaurs evolved.

Skeleton offers caller clues astir maturation and behavior

Lindsay Zanno, the study’s pb writer and a paleontologist astatine the North Carolina Museum of Natural Sciences, said the skeleton challenges assumptions astir maturation successful these animals.

Her squad recovered that Zavacephale had already developed a salient dome contempt not being afloat grown, which suggests the operation whitethorn person served an important relation successful societal signaling oregon contention from an aboriginal age.

Paleontologists digging successful Mongolia person recovered a pristine skeleton of a caller taxon of the famed dome-headed dinosaur. They determined that the fossil belongs to a caller taxon of pachycephalosaur dubbed the Zavacephale rinpoche and is astir 108 to 115 cardinal years old.… pic.twitter.com/QK1c6byOAd

— Robbie Mouton (@mcgmouton57) September 18, 2025

Compared to its aboriginal relatives similar Pachycephalosaurus, which could turn much than 15 feet long, Zavacephale was small—just 3 feet successful magnitude and astir 20 pounds successful weight. Still, its completeness and property marque it a captious portion successful tracing however dome-headed dinosaurs emerged and evolved.

David Evans, a paleontologist astatine the Royal Ontario Museum who was not progressive successful the study, described the fossil arsenic a long-awaited find that fills a important spread successful the evolutionary timeline.

He emphasized that having a afloat skeleton—not conscionable a skull—offers a uncommon accidental to recognize however these dinosaurs’ antithetic anatomy came together.

Discovery pushes backmost evolutionary timeline

Analysis of the fossil besides pushes backmost the known timeline for this radical by astatine slightest 14 cardinal years. Previously, the earliest known subordinate was Sinocephale from China.

The property of Zavacephale indicates that dome-headed dinosaurs archetypal appeared successful Asia and aboriginal dispersed to North America.

The findings besides formed uncertainty connected long-standing interpretations of different fossils. Dinosaurs similar Wannanosaurus, erstwhile thought to correspond the earliest signifier of dome development, whitethorn alternatively beryllium juvenile specimens. Similarly, taxon specified arsenic Dracorex and Stygimoloch whitethorn beryllium younger forms of Pachycephalosaurus, not abstracted species.

Despite decades of study, the intent of the dome remains uncertain. Whether for combat, display, oregon dominance, the operation stood retired for millions of years—leaving a lasting people successful the fossil record.