In Mongolia, paleontologists have found the almost complete fossil of a youthful Pachycephalosaur with a so -called dome head. The Cretaceous bones are about 115 to 108 million years old. This means that this dinosaurs’ talent lived at least 14 million years earlier than the oldest known specimens of this stubborn dinner. The characteristic dome-shaped body feature has earned earlier in dino evolution earlier than previously assumed. The fossil also provides new insights into the physique and the appearance of this dino type.
The herbivorous pachycephalosaurs occurred during the chalk in the northern hemisphere. These two -legged dinosaurs are known for their striking dome -shaped head, which came about through a heavily thickened and enlarged skull bone. These animals, which are therefore also called stubborns, liked this special body feature in the course of evolution in order to attract sexual partners with the jewelry or to flee competitors to outdo these partners by head push duel. “The couplings have not offered protection against predators or to make temperature regulation, so they probably served more to present themselves and to promote the favor of potential partners,” explains senior author Lindsay Zanno from North Carolina State University.
When exactly and why the Pachycephalosaurs and their cathedral head developed has so far been unclear. So far, only a few fossils of this dino-type have been found, many of which were incomplete. “Pachycephalosaurs are iconic dinosaurs, but they are also rare and mysterious,” says Zanno.
Well-preserved dino fossil fills knowledge gaps
Now researchers around Zanno and first author Tsogtbaatar Chinzorig from the Mongolian Academy of Sciences in Ulaanbaatar have found a new Pachycephalosaur fossil. In the Gobi desert in Mongolia, they discovered the remarkable skeleton of a small Pachycephalosaurs with dome head. They called him Zavacephale Rinpoche. “Zava” is Tibetan and means “root” or “origin”, “cephal” is Latin for “head”. “Rinpoche” is Tibetan for “precious” and refers to the arched skull, which the paleontologists found on a cliff like an exposed jewel. The bones come from a rock formation from the early Cretaceous period. At that time, the Mongolian valley was not yet a desert, but was crossed by lakes and surrounded by cliffs or steep walls.
Analyzes of the fossil revealed that this stubborn dump was only about a meter long and weighed 5.85 kilograms. Adult Pachycephalosaurs could be up to 4.3 meters long and weigh up to 410 kilograms. Therefore and due to the young bone structure of the new fossil, the researchers assume that Zavacephale Rinpoche is a dino talent. Since his dome showed only a few of the usual ornaments, but was already well developed overall, he was probably already sexually mature at the time of death, the team suspects. Although his body was more childish, he already had the head of a young adult.
The bones of the young stubborn dump is almost completely preserved, including the skull and the limbs. “It is the most complete surviving skeleton of a Pachycephalosaurs so far,” says Chinzorig. “Zavacephale Rinpoche gives us an unprecedented insight into the anatomy and biology of the Pachycephalosaurs,” adds Zanno. For the first time, for the first time, for the first time, the fossil shows what the hands of the Pachycephalosaurs looked like that they had a fiery cock with covered tendons and that they used stomach stones to shred in food. This physique was previously unknown.
Dome heads developed earlier than expected
In addition, the well -preserved fossil allows a more precise dating of its age. As a result, the dino lived about 115 to 108 million years ago – and thus at least 14 million years earlier than the stubborn dinosaurs, whose fossils have been found so far. “Zavacephale Rinpoche is about 15 million years older than all known Pachycephalosaur fossils,” says Chinzorig. Accordingly, the Zavacephale Rinpoche found is an early form of evolution of the dome navigation, the team closes.
“Zavacephale Rinpoche is an important copy for the understanding of the development of the pests of Pachycephalosaurs, which was discussed for a long time due to the lack of early, divergent or anti-late chalk and the fragmentary nature of almost all pachycephalosaur fossils,” says Chinzor. The newly found fossil fills essential knowledge gaps, both with a view to the timeline and lifetime of this kind as well as with regard to the anatomical development of the individual animals. “Since the head decorations change in the course of growth, it has so far been difficult to determine the respective kind or the development of an animal,” says Zanno. “Now we can connect the growth stage and the development of the dome structure for the first time.”
Source: Tsogtbaatar Chinzorig (North Carolina State University) et al.; Nature, DOI: 10.1038/S41586-025-09213-6