Mongolian Scientists Discover the Oldest Dome-Headed Dinosaur

Dome-Headed Dinosaur

The group of dinosaurs known as "dome-headed" is distinguished by a prominent, rounded bump on the top of their skulls, setting them apart from other dinosaur lineages. Until now, the body structure and anatomy of dome-headed dinosaurs have remained poorly understood due to the extreme rarity of their fossilized remains, making them some of the rarest dinosaurs ever discovered. A collaborative field expedition organized by the Institute of Paleontology of the Mongolian Academy of Sciences has unearthed a remarkable fossil in the “Khuren Dukh” locality, where sedimentary rock layers from the Early Cretaceous period (approximately 108–115 million years ago) are exposed. This discovery is drawing significant attention from paleontologists and dinosaur enthusiasts around the world.

In terms of geological time, Zavacephale is now considered the earliest known representative of the dome-headed dinosaur group.

The fossil consists of a skull and postcranial skeleton, with an estimated body length of about 80 cm and a weight of 5.85 kg. It belonged to a herbivorous dome-headed dinosaur. The specimen includes bones of the shoulder girdle, upper limbs, vertebrae, pelvis, hind limbs, a tail with tendons, and gastroliths (stomach stones). Among dome-headed dinosaurs, it is considered one of the most complete and best-preserved specimens ever found. Due to its rarity, the geological age in which it lived, and the condition in which it was found, the scientists have named this new dinosaur Zavacephale rinpoche, a name that combines words meaning “first dome-head” and “precious, rare.”

Zavacephale is also the first dome-headed dinosaur ever found with preserved forelimb elements and gastroliths, adding to its scientific significance. Anatomical features of the skull and body, along with histological (tissue-level) analysis of the limb bones, indicate that the individual was fully grown at the time of death. Again, based on its geologic age, Zavacephale represents the earliest known member of the dome-headed dinosaur lineage.

The study was led by Dr. Ts. Chinzorig from the Institute of Paleontology at the Mongolian Academy of Sciences. Other contributors include researchers B. Buyantegsh, B. Mainbayar, Dr. Kh. Tsogtbaatar, and their colleagues. This important discovery was published in the September 17, 2025, issue of Nature, one of the world’s most prestigious scientific journals, with an impact factor of 50.