Researchers discover 200-million-year-old African dinosaur

In a new study published in the journal Nature, paleontologists describe the discovery of the skeleton of an early dinosaur called Mbiresaurus raathi, which lived in Zimbabwe, Africa, more than 200 million years ago.

The fossils were discovered by a graduate student from Virginia Tech’s Department of Geosciences and other paleontologists over the course of two excavations, in 2017 and 2019. Surprisingly, most of the skeleton is still complete.

The findings of this new sauropodomorph signify the oldest dinosaur skeleton that has been discovered so far in Africa. The animal had a long tail and was said to be 1.8 meters long, weighing from 10 to 29 kilograms.

The remains, which were discovered in northern Zimbabwe, were only missing parts of the hand and skull.

“These are the oldest definitive dinosaurs in Africa, roughly equivalent in age to the oldest dinosaurs found anywhere in the world,” Christopher Griffin, who graduated in 2020 in geosciences from Virginia Tech College of Science, said in a statement.

The oldest known dinosaurs – from around 230 million years ago, the Carnian stage of the Late Triassic period – are extremely rare and have been recovered in only a few places in the world, mainly northern Argentina, southern Brazil and India, he continued.

Discovering Mbiresaurus raathi

“The discovery of Mbiresaurus raathi fills a critical geographic gap in the fossil record of the oldest dinosaurs and shows the power of hypothesis-based fieldwork to test predictions about the ancient past.”

Research says that early dinosaurs such as Mbiresaurus raathi show that the early evolution of these animals is still being written about with each new discovery and the rise of dinosaurs was much more complicated than previously anticipated.

“We never expected to find such a complete and well-preserved dinosaur skeleton,” said Griffin, now a postdoctoral researcher at Yale University.

“When I found the Mbiresaurus femur, I immediately recognized it as belonging to a dinosaur and knew that it was holding the oldest dinosaur ever found in Africa. When I continued digging and found the left hip bone next to the left thigh bone, I had to stop and breathe – I knew a lot of the skeleton was probably there, still articulated in a living position.

A theory about the dispersal of dinosaurs

In addition to the discovery of Mbiresaurus, the group of researchers also has a new theory about the migration of animals, including when and where.

Africa, like all continents, was once part of the supercontinent called Pangea. The climate across Pangea is thought to have been divided into strong wet and arid latitudinal belts, with more temperate belts spanning higher latitudes and intense deserts in Pangea’s lower tropics.

According to the researcher, scientists previously believed that these climate belts influenced and restricted the distribution of animals across Pangea.

“Since dinosaurs initially dispersed under this weather pattern, the early dispersal of dinosaurs should therefore have been controlled by latitude,” Griffin said.

“The oldest dinosaurs are known at approximately the same ancient latitudes along the southern temperate climate belt as it was at the time, approximately 50 degrees south,” he continued.

Griffin and others at Virginia Tech’s Paleobiology and Geobiology Research Group purposely targeted northern Zimbabwe as the country fell along that same climate belt, filling a geographic gap between southern Brazil and India during the Late Triassic.

Furthermore, these early dinosaurs were restricted by climatic bands south of Pangea, and only later in their history did they disperse across the world.

The research team, to reinforce the thesis, developed a new data method to test this hypothesis of climatic dispersion barriers based on ancient geography and dinosaur family tree.

The breakdown of these barriers and a northward scattering wave coincided with a period of intense global humidity, or the Carnian Pluvial Event.

Afterwards, the barriers returned, anchoring dinosaurs now all over the world in their distinct provinces in Pangea for the remainder of the Triassic Period, according to the team.

According to Griffin, “This dual approach combines hypothesis-based predictive fieldwork with statistical methods to independently support the hypothesis that the first dinosaurs were restricted by climate to only a few areas of the globe.”

Brenen Wynd, also a PhD candidate in the Department of Geosciences, helped build the data model. “The early history of dinosaurs was a critical group for this kind of problem. Not only do we have a plethora of physical fossil data, but also geochemical data that previously gave a good idea of ​​when major deserts were present,” he said.

“This is the first time that these geochemical and fossil data have been supported using only evolutionary history and the relationships between different dinosaur species, which is very exciting.”

other fossils

The research team also found a variety of fossils from the Carnian age, including a herrerasaurid dinosaur, relatives of early mammals like cynodonts, relatives of armored crocodilians like aetosaurs, and, in Griffin’s description, “archaic and bizarre reptiles” known as rhynchosaurs, again. typically found in South America and India from this same period.

The name Mbiresaurus is derived from Shona and Ancient Greek roots. “Mbire” is the name of the district where the animal was found and is also the name of a historic Shona dynasty that ruled the region. The name “raathi” is in honor of Michael Raath, a paleontologist who first reported fossils in northern Zimbabwe.