The Earliest Known Dome-Headed Dinosaurs of Mongolia

A dinosaur with a dome-shaped head, discovered in Mongolia, boasted a mouth full of formidable teeth and an unusually large eye socket on its skull.

The newly identified species, named Zavacephale rinpoche, roamed the Earth during the early Cretaceous period about 108 million years ago. It belongs to a group known as the Pachycephalosaurs. These dinosaurs were characterized by their dome-like skulls, which may have served defensive purposes or been used for social and mating displays.

Paleontologists exploring the Gobi Desert of Mongolia report having uncovered a fossilized skull protruding from the rocks, likening it to a “cabochon gem.” Lindsey Zanno from the North Carolina Museum of Natural Sciences stated, “This is how we came up with the species name Rinpoche, which translates to ‘precious things’ in Tibetan.”

Z. rinpoche represents the most complete specimen of its kind discovered to date, being about 15 million years younger than other known Pachycephalosaur species. It includes nearly the entire skull and limb bones, significant portions of the vertebrae, and pelvic bones. Additionally, the team was able to recover hand bones and gastroliths, which were likely used to grind food.

The dome of the fossil shows distinct dimples, possibly indicating other unidentified features of the head.

“The skull of Pachycephalosaurs is quite striking,” says Zanno. “They not only feature domes, but also bone spikes and nodes surrounding their skulls for aesthetic purposes. These embellishments served as sort of decorative accessories for the dome.”

To ascertain the age at which the dinosaur perished, researchers examined thin slices of the bones from its lower limbs. They classified it as a “teenager,” measuring approximately one meter in length and weighing just under six kilograms. It remains uncertain how large it might have become as an adult, though other members of its group reached lengths exceeding four meters and weights around 400 kilograms.

“The preserved tissues show two growth rings, suggesting that it was actively growing at the time of its death,” noted Zanno. “The spinal bones exhibit no signs of wear, indicating room for further growth.”

CT scans of the skull dome revealed it was fully developed, emphasizing its significance at a younger age.

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