240-million-year-old Tanzanian fossil revises timeline of early dinosaur rocks

An international team led by the University of Bristol has named a new species of prehistoric animal from Tanzania, Dinodontosaurus isiyavamanda, which lived about 240 million years ago in the Triassic period. The species was formally described in the Journal of Vertebrate Palaeontology on September 16, 2026, and its presence in Tanzania is prompting a rethink of how old the country's earliest dinosaur fossils are.

Fossils that waited 60 years

The fossils come from a large collection of synapsids gathered during a British expedition to Tanzania in 1963, according to the University of Bristol. Synapsids are mammal-lineage vertebrates, and many groups flourished before dinosaurs became dominant. The specimens were housed at the Natural History Museum in London but remained largely unstudied for decades.

The researchers examined an undescribed skeleton belonging to the dicynodonts, a herbivorous group of synapsids, along with a recently discovered fragmentary skull, and concluded that they belong to the genus Dinodontosaurus.

Part of the work dates back three decades. Nigel Larkin, a visiting research fellow at the University of Reading, said: "I studied this dicynodont skeleton for my MSc thesis at University College London back in 1994."

Mike Day, curator of non-mammalian tetrapods at the Natural History Museum, said: "This fossil specimen from Tanzania has been in our care for over 60 years, and it's wonderful that its identity has now been brought to light."

According to the university, "The name is a reference to the land of the Wamanda people, who inhabit the region of Tanzania where the fossils were found."

First record outside South America

Until now, Dinodontosaurus was known only from South America. "Our discovery marks the first confirmed record of the genus Dinodontosaurus outside South America," said lead author Hady George, a PhD student at the University of Bristol's School of Earth Sciences.

Because the same genus appears in both places, the finding creates a link between the Triassic rock sequences of Tanzania and South America, indicating they are equivalent in age, the university says.

A shift in the dinosaur timeline

That link matters because of recent dating work. According to the University of Bristol, new radiometric dating from South America suggests the early dinosaur-bearing rock sequences there are up to 10 million years younger than those of South Africa. The release concludes that "the Triassic rocks of Tanzania can no longer be regarded as preserving the oldest potential dinosaur fossils, prompting a reassessment of when and where dinosaurs first evolved."

George said: "This helps confirm that the oldest dinosaur candidates from Tanzania are probably no older than those from South America, refining the timeline of dinosaur origins."

Why it matters

Tanzania's Triassic rocks have been seen as a possible home of some of the oldest dinosaur relatives, so their age shapes ideas about where and when dinosaurs first appeared. By tying those rocks to South American sequences, a plant-eating dicynodont rather than a dinosaur has become a useful dating marker. The study also shows how long-stored museum collections can still yield new species and reshape scientific timelines.

Sources

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