A newly discovered dinosaur species has been identified from a fossil unearthed in Mongolia that represents the most complete pachycephalosaur specimen yet foundAnyone who has ever flipped open a dinosaur book is likely familiar with pachycephalosaurs. A pachycephalosaur skeleton that was recently discovered in Mongolia is poised to finally fill in the missing chapter of this dinosaur clade’s early history. The remarkably complete fossil, which Zanno and her colleagues described on Wednesday in the journal Nature, represents a new species that is the oldest known dome-headed dinosaurs. North Carolina Museum of Natural SciencesAs the researchers chipped away at the surrounding rock, they quickly realized that the new specimen represented the most complete pachycephalosaur fossil ever discovered. Brusatte thinks that future finds of early pachycephalosaurs may further reveal how the group’s signature headgear evolved over time.