South African scientist discovers rare dinosaur fossil in Mongolia's Gobi Desert

In a groundbreaking discovery that promises to shed light on a rare and enigmatic group of dinosaurs, Dr Ryan Tucker from Stellenbosch University’s Department of Earth Sciences has played a pivotal role in unveiling the teenage fossil of a previously unknown species of pachycephalosaur in Mongolia’s Gobi Desert.

This significant find is not only the oldest member of its lineage, but also boasts the most complete skeleton ever extracted from this dinosaur family.

The research, which includes a team of international scientists and was published on September 17 in the prestigious journal Nature, highlights the potential of this 'teenaged' specimen to answer lingering questions surrounding the evolution and biology of pachycephalosaurs, a dinosaur group characterised by their distinctive domed skulls.

Lead author Tsogtbaatar Chinzorig from the Mongolian Academy of Sciences unearthed this remarkable skeleton in the Khuren Dukh locality of the Eastern Gobi Basin. Named Zavacephale rinpoche, the new species' name translates to 'root head' in Tibetan, with 'rinpoche' meaning 'precious one' — a fitting tribute to its strikingly preserved skull that was discovered embedded in a cliff, akin to a cabochon jewel.

The dinosaur roamed the Earth approximately 108 million years ago during the Early Cretaceous period, at a time when the present-day Gobi region was a lush valley dotted with lakes, offering a rich habitat for herbivores like Z. rinpoche. This adolescent dinosaur would have weighed between 360kg and 408kg and stood about 2.1m tall, growing to around 4.3m in adulthood.

“Z. rinpoche predates all known pachycephalosaur fossils by about 15 million years,” Chinzorig stated. Despite its relatively small size — measuring less than one metre in length — the specimen is extensively complete, providing an invaluable resource for understanding the evolutionary path and growth patterns of these unique creatures.

Interestingly, while the specimen displayed a fully developed dome, a signature feature of pachycephalosaurs, it lacked many of the ornamental traits seen in later species. This revelation is poised to deepen our understanding of skull dome development, given that the fossil record for early diverging forms has been historically scant and fragmentary.

Paleontologists have long grappled with differentiating between species based on cranial morphology and growth stages. The discovery of Z. rinpoche opens new avenues for research, enabling scientists to correlate dome development with growth stages more effectively than before.

Dr Lindsay Zanno from North Carolina State University pointed out, “While pachycephalosaurs are renowned for their dramatic domed heads, we must look beyond mere aesthetics to unravel their biological significance.”

Encouragingly, advanced techniques allowed researchers to inspect the lower leg bone structure, affirming that this dinosaur, despite having an adult-shaped dome, was still a juvenile at the time of its demise. This juxtaposition brings us one step closer to answering the enticing yet perplexing questions surrounding the growth and behaviour of these extraordinary reptiles.

Pachycephalosaurs, often characterised by their impressive domed skulls, have long fascinated scientists and the public alike.

Zanno notes, “The prevailing theory suggests these domes were used for socio-sexual displays rather than defence. This fossil provides insight into how this exhibition of ornamentation could evolve.”

This significant find not only extends the timeline of the pachycephalosaur lineage but also offers a rare glimpse into their anatomical and biological features, including appendage structures and potential dietary practices. “The discovery of gastroliths, or stomach stones, alongside the recovered materials, reshapes our understanding of how pachycephalosaurs processed their food,” Chinzorig commented.

This remarkable specimen exemplifies the dynamic nature of paleontological research and serves as a reminder of the mysteries that still linger beneath our seabed and within our ancient landscapes. As Z. rinpoche reinvigorates the conversation surrounding the evolution of this dinosaur group, the research team remains committed to further exploration and discovery.