In a remarkable find, paleontologist Chinzorig Tsogtbaatar and his team discovered a new species of pachycephalosaur during a field expedition in southeast Mongolia. The discovery took place at a rocky outcrop dating back approximately 110 million years to the early Cretaceous period.
Tsogtbaatar recalled the moment he spotted an unusual, bright object on the other side of a hill. ‘It didn’t look like a rock,’ he stated, recalling the surprising sighting of what turned out to be a dome-shaped skull.
The significance of this find is profound, as this new species, named Zavacephale rinpoche, fills a critical gap in our understanding of the evolution of dome-headed dinosaurs. According to Lindsay Zanno, head of paleontology at the North Carolina Museum of Natural Sciences and a colleague of Tsogtbaatar, this creature is the first definitive pachycephalosaur found from the early Cretaceous.
The name Zavacephale rinpoche, which incorporates the Tibetan word for ‘precious one’, is a fitting tribute to the beautifully preserved dome that Tsgotbaatar discovered. This discovery represents a monumental addition to the fossil record, as it is dated 15 million years older than the previous known oldest pachycephalosaur.
After the specimen was excavated in 2019, it was kept in Mongolia during the COVID-19 pandemic. In 2022, it was finally transported to North Carolina for further analysis. Zanno expressed her enchantment upon seeing the skull for the first time, describing it as ‘the most beautiful specimen. It’s magical.’
Pachycephalosaurs are primarily recognized for their thick, bony, hemispherical skulls, which serve as their most distinguishing feature. Zanno stated that these domes are effectively indestructible, hinting at the idea that these animals likely engaged in head-butting behavior.
The discovery was further enhanced by the excavation of numerous additional bones from Zavacephale rinpoche, making it the most complete pachycephalosaur skeleton ever found. Zanno likened the size of the dinosaur to that of a German shepherd, noting that its lightweight build, primarily consisting of a long neck and tail, meant it would have only weighed around 12 pounds.
This remarkable fossil has already provided new insights into the life of pachycephalosaurs. Notably, the stomach contents revealed small stones, which would have aided in their digestion. Furthermore, the findings included a tail reinforced by bony tendons, contributing to its rigidity.
For the first time, researchers have also uncovered the hand bones of a pachycephalosaur with Zavacephale rinpoche. Initial analysis led to a mistaken belief that the tiny bones might have been ingested rather than part of its anatomy, highlighting the size difference.
Through the examination of limb bones, researchers determined that the specimen was at least two years old, classifying it as a juvenile. Importantly, this indicates that young pachycephalosaurs developed fully formed domes at a surprisingly early age.
The purposes of those domes remain uncertain, be it competition for territory or mates, but Zanno emphasized that whatever behavior they exhibited started at a very young age.
Currently, the specimen is housed at the Institute of Paleontology of the Mongolian Academy of Sciences, reflecting a commitment to preserving the country’s natural and cultural heritage. Cary Woodruff, a curator of vertebrate paleontology at the Frost Museum of Science in Miami, expressed his profound admiration for the discovery, stating it was both astonishing and elicited a sense of ‘very friendly jealousy’ for Tsogtbaatar’s find.
Woodruff remarked, ‘How he even found the specimen is just bonkers. He doesn’t just find a new one. He finds the geologically oldest one—it’s exactly what everyone who works on pachycephalosaurs has always wanted to find.’
David Evans, a dinosaur paleontologist at the Royal Ontario Museum in Toronto, echoed this sentiment, expressing his awe at the fossil’s beauty and completeness. Evans stated, ‘This is a specimen that we’ll be learning from for many, many years to come.’
In conclusion, the discovery of Zavacephale rinpoche not only enriches the fossil record but also enhances our understanding of the early evolution of pachycephalosaur dinosaurs, unveiling insights into their biology and behavior during the Cretaceous era.
image source from：npr
