Paleontologists have discovered a new species of dome-headed dinosaur, Zavacephale rinpoche, in Mongolia's Gobi Desert, dating back approximately 108 million years during the Early Cretaceous period, making it the earliest known pachycephalosaur.

The fossil, which includes a well-preserved skull, limbs, and other bones, allows scientists to study growth stages and dome development together for the first time in pachycephalosaurs.

Analysis indicates that the juvenile had a fully developed dome before reaching full size, suggesting that dome growth was linked to socio-sexual behaviors rather than age or size, supporting theories of their use in display and mating competitions.

The prominent dome was likely used for socio-sexual signaling, such as competing for mates, rather than for defense or temperature regulation, with evidence supporting head-butting behavior.

Researchers hypothesize that the domes were used for social dominance and mating rituals, possibly involving head-butting or grappling, emphasizing their role in sexual selection.

Fossil evidence shows signs of trauma consistent with head-butting, supporting the hypothesis that pachycephalosaur domes were used in combat.

The environment where Zavacephale lived was a diverse ecosystem with lakes, cliffs, herbivorous dinosaurs, fish, turtles, and crocodile relatives.

Zavacephale rinpoche was a small herbivore, about three feet long and weighing around 20 pounds, likely sexually mature, and smaller than later pachycephalosaurs like Pachycephalosaurus.

The discovery, published in the journal Nature, enhances understanding of pachycephalosaur behavior and development, and supports the idea that their social and behavioral significance was established early.

The age of the fossil suggests that pachycephalosaurs emerged at least 14 million years earlier than previously thought, originating in prehistoric Asia before spreading to North America.

This discovery challenges previous assumptions by showing that early pachycephalosaurs evolved a fully domed skull early in their history, with some fossils now considered juvenile forms rather than early-stage species.

The fossil's dome is covered with dimples, indicating possible additional features, and skull ornamentation highlights the importance of display features like spikes and nodes in pachycephalosaurs.

Detailed data, including geographic coordinates, phylogenetic analyses, and morphometric data, are publicly available, supporting transparency and further research.