New Fossil Mammal Relative from Tanzania May Rewrite the Age of Early Dinosaurs

Paleontologists have identified a new species of ancient mammal relative from two fossil specimens discovered decades apart in Tanzania’s Manda Formation. The finding suggests that rocks associated with some of the earliest potential dinosaur fossils may be younger than scientists have long assumed.

Dinodontosaurus isyavamanda lived about 240 million years ago

Named Dinodontosaurus isyavamanda, the new species lived during the Triassic Period approximately 240 million years ago.

The animal was a plant-eating dicynodont, a group of beaked, tusked therapsids that were distantly related to modern mammals. Dicynodonts were among the important herbivores living before and during the early age of dinosaurs.

Dinodontosaurus isyavamanda belongs to the genus Dinodontosaurus, which was previously known only from South America.

“Our discovery marks the first confirmed record of this genus, Dinodontosaurus, outside of South America,” said lead author Heidi George, a PhD student at the University of Bristol.

“This discovery links fossil-bearing rocks from Tanzania and South America and shows that they are of comparable age.”

Fossils discovered nearly 50 years apart

A skull and partial skeleton of Dinodontosaurus isyavamanda were collected in 1963 from the Lihua Member of Tanzania’s Manda Formation. A second specimen was recovered in 2012.

Paleontologists used CT scans and three-dimensional surface imaging to examine the fossils in detail. They then conducted a phylogenetic analysis, comparing the Tanzanian animal with its South American relatives.

Dr. Mike Day, Curator of Non-Mammalian Tetrapods at London’s Natural History Museum, said the fossil had been in the museum’s care for more than 60 years.

“This fossil specimen from Tanzania has been in our care for over 60 years and it’s great that its true identity has been revealed,” Day said.

“By clarifying that Dinodontosaurus originated in both South America and eastern Africa, these fossils offer a glimpse into what Earth was like 240 million years ago.”

“This shows how revisiting museum collections can change our understanding of the past as much as discovering new fossils in the field, and demonstrates the importance of looking after these precious records of life on Earth.”

New fossil evidence may change the age of Tanzania’s dinosaur-bearing rocks

Because Dinodontosaurus is also known from reliably dated rock sequences in Brazil and Argentina, its presence in Tanzania gives researchers new evidence that the middle and upper layers of the Manda Formation are younger than previously believed.

The formation produced what is believed to be the oldest known dinosaur, Nyasasaurus parringtoni, along with other early dinosaur relatives. If the rocks are younger than traditionally estimated, those animals may have appeared later in Earth’s history than previously thought.

According to the researchers, the presence of Dinodontosaurus in Tanzania indicates that the middle and upper Lihua Member was probably deposited around the same time as the Dinodontosaurus assemblage zone in Brazil and the Chañares Formation in Argentina.

The scientists suggest that the middle and upper Lihua Member may date from the Late Ladinian, approximately 242–237 million years ago, to the Carnian, approximately 237–227 million years ago. This would make it younger than the historically proposed Anisian age of approximately 247–242 million years ago.

“Future studies should consider this young age of the middle to upper Lihua Member when investigating the origins of the major Mesozoic clades that include dinosaurs,” the researchers said.

Study publication

The research was published in the Journal of Vertebrate Paleontology.

Read the paper.

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Heidi George et al. 2026. Craniomandibular osteology of Dinodontosaurus isyavamanda sp. nov. (Therapsida: Anomodontia) from the Manda Formation of Tanzania, and new support for a younger age of the putatively oldest dinosaurs. Journal of Vertebrate Paleontology, in press. doi: 10.1080/02724634.2026.2692542