New South African dinosaur Nyana rooiwalensis was heavy as a youngster

Heavyweight juvenile fossil found

Researchers led by Atashni Moopen of the University of the Witwatersrand announced the discovery of Nyana rooiwalensis. That animal resided over 200 million years back in the area currently known as the Eastern Cape Province. The team used powerful X-rays to build a detailed three-dimensional model of its near-complete skull. Microscopic examination of limb bone slices showed the animal was still growing rapidly when it died.

Growth and weight estimates

Scientists estimated the juvenile weighed approximately 400 kilograms or 880 pounds based on thigh bone measurements. The study authors suggest adult individuals may have reached multi-tonne body masses through extrapolation of growth curves. Nyana belonged to sauropodomorphs, a group that eventually produced long-necked giants like Brachiosaurus and Diplodocus. Fossilized skulls from this specific age are relatively rare in southern Africa where the remains were found.

Evolutionary significance of find

The discovery provides critical new data on skull morphology for early-diverging massopodans used in future phylogenetic studies. The finding points to a new connection linking southern Africa with North America in the context of how dinosaurs evolved. The paper was published in the journal Royal Society Open Science with DOI 10.1098/rsos.261002.