Tanzanian Fossil Pushes Back Dinosaur Ancestry by 20 Million Years

An international team of paleontologists has announced the discovery of a previously unknown prehistoric animal from Tanzania that lived roughly 240 million years ago, during the Middle Triassic. The find, described in a recent scientific paper, adds a new species to the fossil record and could shift the timeline for when the first true dinosaurs appeared.

The creature, named Dinodontosaurus isiyavamanda, was uncovered in sedimentary layers of the Ruhuhu Basin, a region already known for yielding early archosaur remains. Radiometric dating and stratigraphic analysis place the fossil at the Ladinian stage of the Triassic, making it about 20 million years older than the earliest confirmed dinosaurs.

Researchers say the anatomical features of Dinodontosaurus bridge a morphological gap between basal archosaurs and later dinosauriforms. Its skull and dentition display a mix of primitive traits and derived characteristics that are hallmarks of early dinosaur evolution, suggesting that the split between dinosaur ancestors and their contemporaries may have occurred earlier than previously thought.

The Triassic period was a time of rapid diversification among reptilian lineages, with archosaurs branching into several groups that would later dominate the Mesozoic. Prior to this discovery, the consensus placed the emergence of true dinosaurs in the late Triassic, around 230 million years ago. The new specimen provides concrete evidence that the evolutionary experiment leading to dinosaurs was already underway in the middle of the period.

The study was led by scientists from the University of Bristol, working alongside colleagues from Tanzania, Germany and the United States. Using high‑resolution CT scanning, the team reconstructed the fossil’s skeletal geometry without damaging the delicate bones. Comparative analysis with other Triassic taxa helped pinpoint the animal’s phylogenetic position and supported the proposal of a new species.

While the find does not rewrite the entire narrative of dinosaur origins, it underscores the importance of underexplored fossil sites in Africa. The authors anticipate that further fieldwork in the Ruhuhu Basin could reveal additional specimens that clarify the early steps of dinosaur evolution. As more data emerge, the scientific community will reassess models of archosaur diversification and the environmental factors that may have driven the rise of dinosaurs.