A fossil that spent more than six decades in a museum collection has turned out to be far more important than anyone first realised.

Researchers have identified a previously unknown species of prehistoric animal from Tanzania, and the discovery could change how scientists date some of the earliest possible dinosaur remains.

The new species, named Dinodontosaurus isiyavamanda, lived around 240 million years ago during the Triassic period. It belonged to a group called dicynodonts, herbivorous synapsids from the broader evolutionary lineage that eventually gave rise to mammals. The study was published in the Journal of Vertebrate Palaeontology.

A Fossil Hidden In Plain Sight

The story began in 1963, when a British expedition collected a large number of fossils in what is now Tanzania. Many of the specimens were later stored at the Natural History Museum in London, but some remained only partly studied for decades.

Among them was an associated skeleton belonging to a dicynodont, along with a more recently discovered fragmentary skull. Detailed anatomical work eventually showed that these remains belonged to the genus Dinodontosaurus.

That was unexpected. Until now, this genus had been known only from South America. Further study confirmed that the Tanzanian fossils represented an entirely new species. The name isiyavamanda refers to the land of the Wamanda people who live in the region where the fossils were found.

A Link Between Africa And South America

The discovery is important for more than taxonomy.

Because Dinodontosaurus is now known from both Tanzania and South America, scientists can use it to connect the ages of rock layers found on the two continents. The presence of the same genus in both regions suggests that the fossil-bearing deposits are broadly equivalent in age.

That connection matters because the Tanzanian rocks have also produced fossils thought to represent some of the oldest possible dinosaurs, including Nyasasaurus and the silesaur Asilisaurus.

These deposits were previously compared with Middle Triassic rocks in South Africa. However, newer radiometric dates from South America suggest that similar fossil-bearing layers may be up to 10 million years younger than the South African sequences.

The Dinosaur Timeline May Need Adjusting

If the Tanzanian rocks are the same age as those in South America, then the alleged earliest dinosaur fossils from Tanzania may also be younger than previously believed.

Hady George, a PhD researcher at the University of Bristol and lead author of the study, explained that the new species provides the first confirmed record of Dinodontosaurus outside South America. He said this connection helps show that the Tanzanian and South American fossil deposits are comparable in age, strengthening the case that the oldest dinosaur candidates from Tanzania are probably no older than those already known from South America.

That does not mean the fossils are unimportant. Instead, it refines the broader question of when and where the earliest dinosaurs evolved.

Museum Collections Still Hold Surprises

The discovery also highlights the scientific value of specimens collected many decades ago.

Palaeontologist Nigel Larkin first studied the dicynodont skeleton for his MSc thesis in 1994 and suspected that it represented a new species. Nearly 30 years passed before the specimen was formally described. Larkin explained that advances such as micro-CT scanning and easier international collaboration now allow researchers to study old fossils in far greater detail than was possible in the 1990s.

Dr Mike Day of the Natural History Museum similarly noted that revisiting historical collections can transform scientific understanding just as much as discovering new fossils in the field.

More Fossils Still Need Study

Much of the Tanzanian material remains to be examined, especially parts of the skeleton below the skull.

Future research will compare these bones with South American specimens and investigate how Dinodontosaurus moved, fed and shared its environment with other large herbivores.

The discovery is a reminder that palaeontology does not always depend on dramatic new excavations. Sometimes, the fossils capable of rewriting evolutionary history have already been sitting quietly in museum drawers for generations.