Teenage “Dick-head” Dinosaur Rewrites Pachycephalosaur Evolution Timeline
ULAANBAAR, Mongoliaโ – September 18, 2025 โ – Aโฃ newly discovered โคfossil inโฃ Mongolia reveals Zavacephale Rinpoche, aโ teenage Pachycephalosaur, representsโ the earliest known evolutionaryโข form of โคthe iconic โdome-headed dinosaur. The find pushes back the timeline โforโฃ the development of this distinctive feature and provides unprecedented insights into the growth and anatomy of these “bone-headed” dinosaurs.
The fossil, analyzed by a team led by paleontologists from North Carolina State university andโ theโ Mongolian โAcademy of Sciences, dates to a period earlier than previously understood for advanced Pachycephalosaurs. Researchers persistent the specimen was approximately one metre long and weighed 5.85 kilograms, significantly smaller than adult Pachycephalosaurs โข which could reachโฃ 4.30 meters in length and weigh up to 410 kilograms. This, โcoupled with โthe bone โขstructure, indicates Zavacephale Rinpoche was a juvenile.
“Zavacephale Rinpoche gives us an unprecedented insight into the โanatomy and biology of the Pachycephalosaurs,” saeid Dr. Lindsay Zanno. The fossil exhibits aโ well-developed, though less ornate, skull thickening characteristicโ of the species. Researchers also discovered evidence the dinosaur โขused gastrolithsโฃ -โฃ stomach stones – to aid in food digestion, aโฃ previously unknown trait. Furthermore, the team confirmed these dinosaurs possessed a flexible neck withโ covered tendons.
“Since the head decorations change in โthe course of โgrowth,it has so far been difficult to determine the respective kind orโค the development of an animal,” explained Zanno. โ”Now we can do that for the first time and connectโ theโ development of the dome structure.”
Paleontologist Chinzorig added, “Zavacephale Rinpoche is an important specimen for understanding the development of the crests ofโ Pachycephalosaur.” The revelationโ fills critical knowledge gaps regarding the species’ timeline, lifespan, and โanatomical development.
The research was published in Nature (2025; DOI: 10.1038/S41586-025-09213-6).
Sources: North Carolina State University, Nature.