‘Proudly SA’ dinosaur
NEW SPECIES: RESEARCHER RECLASSIFIES PREVIOUSLY STUDIED FOSSIL
Specimen has been in Wits’ Evolutionary Studies Institute collections since 1978.
About 200 million years ago, dinosaurs roamed the Earth and among them, in what is today southern Africa, was the plant-eating Massospondylus carinatus.
The supercontinent Pangaea was still intact; it was the Late Triassic-Early Jurassic epoch.
Fast forward to the present, where I am a researcher who has spent the past six years studying Massospondylus carinatus. The aim of my research has been twofold: better understanding and describing the anatomy of Massospondylus, as well as understanding how it grew as it aged.
Hundreds of Massospondylus fossils have been collected in southern Africa, ranging in size from baby to adult. One has been in the collections at the University of the Witwatersrand’s Evolutionary Studies Institute since 1978. The fossil has been included in research before.
But it’s been incorrectly viewed simply as a deformed Massospondylus specimen. It was nicknamed the “Grey Skull” specimen. As part of my PhD, I scanned it to get a better picture of what it looked like inside. I used a CT scan – a method which has revolutionised the world of palaeontology: we can now reconstruct and visualise fossils at an unprecedented level of detail.
And my scans presented some surprising findings – they suggested the Grey Skull was not just another Massospondylus specimen. Further testing and examination established it was an entirely new, previously undescribed species and genus. The species, which we’ve named Ngwevu intloko (grey skull in isiXhosa), is an additional piece of the puzzle in understanding what our world looked like 200 million years ago. Ngwevu and Massospondylus lived in the Jurassic period, which came just after the
End-Triassic Extinction – one of the largest extinction events. The more we know about the animals that lived in this time, the more we can comprehend how species react and recover after an extinction event.
So how did I realise Grey Skull might be more than just a deformed Massospondylus specimen? When specimens are deformed during fossilisation, they have a lot of cracks or are asymmetrical. The Grey Skull has very few cracks and is very symmetrical. The proportions of the skull and features on the bones are different. The rest of the skeleton also has noticeable differences, including on the pelvis. But the CT scans were just one step in the process.
To be certain a fossil belongs to a new species, it is crucial to rule out the possibility it is a younger or older version of an existing species. My PhD supervisors and I had to rule out the possibility the Grey Skull might be a teenage Massospondylus.
This is a difficult task to accomplish with fossils – it’s rare to have a complete age series of fossils from a single species. Luckily, Masssospondylus has a great fossil record and we were able to look at what changes it goes through when it grows and whether these were similar to those seen in the Grey Skull. This allowed us to rule out age as an explanation for the differences we observed.
Originally, the assumption was the fossil would be very closely related to Massospondylus. But when we ran the analysis, we found its closest relative is a dinosaur found in China called Lufengosaurus. We named the new species Ngwevu intloko to honour SA’s heritage. IsiXhosa is the country’s second most spoken language, and Ngwevu intloko is a proudly South African dinosaur.
Kimberley Chapelle is a PhD candidate in vertebrate palaeontology at the University of the Witwatersrand.
Republished from TheConversation.com