New Dinosaur Weighed 400 kg at Age Three — and Wasn't Done Growing

For age and growth, the team cut thin slices of limb bones and examined them under a microscope. The bone structure showed Nyana was still growing rapidly when it died. The researchers believe it was at least in its third year of growth — despite already weighing as much as a large horse.

Weight came from the thigh bone. The team measured its circumference and compared it against growth curves derived from related dinosaurs. The verdict: big, but far from finished.

"Extrapolation of these growth curves suggests that adult Nyana may have reached multi-tonne body masses," the study authors wrote in their paper.

It's an extrapolation, so treat the multi-tonne figure as a projection, not a measurement. No adult Nyana skeleton has been found.

Why does one skull matter?

The discovery isn't just about a single animal. The researchers argue it could reshape how scientists understand the early evolution and global spread of these dinosaurs.

"It provides critical new data on skull morphology in early-diverging massopodans that will be of use to future phylogenetic studies, suggests a novel biogeographical link between southern Africa and North America and supports the adoption of rapid growth strategies early in sauropodomorph evolution," the authors wrote.

That's three claims bundled in one sentence, each worth unpacking:

• Skull data: The near-complete skull adds missing anatomical detail on massopodans, an early sauropodomorph group, which should sharpen future family-tree analyses (phylogenetics — the science of working out how species are related).
• A continent-hopping link: The fossil hints at a previously unknown biogeographical connection between southern Africa and North America, implying these dinosaurs' relatives spread between the two regions.
• Fast growth, early on: The bone evidence supports the idea that rapid growth strategies appeared very early in sauropodomorph evolution — long before the group's giant descendants came along.

All three rest on one incomplete specimen, and the authors themselves frame the biogeographical and growth conclusions as suggestions and support, not settled fact. Still, a near-complete skull from a time and place with few such fossils gives paleontologists real material to test those ideas against.

The takeaway

A three-year-old, two-legged South African dinosaur already tipping the scales at 400 kg — with multi-tonne adulthood possibly ahead — shows giant-scale growth strategies took root surprisingly early in sauropodomorph history.

The paper: Atashni Moopen et al., "Nyana rooiwalensis: South Africa's earliest near-complete sauropodomorph dinosaur skull from the Late Triassic of the Eastern Cape Province," Royal Society Open Science (2026). DOI: 10.1098/rsos.261002.