Discovery of Mbiresaurus gives birth to new theory on dinosaurs in Supercontinent Pangea

The discovery of Mbiresaurus in Zimbabwe has led the group of researchers to propose a new theory on dinosaur migration, as Africa was once part of the supercontinent called Pangea.

The climate across ancient Pangea continent is thought to have been divided into strong humid and arid latitudinal belts, with more temperate belts spanning higher latitudes and intense deserts across the lower tropics of Pangea. Scientists previously believed that these climate belts influenced and constrained animal distribution across Pangea.

“Because dinosaurs initially dispersed under this climatic pattern, the early dispersal of dinosaurs should therefore have been controlled by latitude,” said Christopher Griffin, who graduated in 2020 with a Ph.D. in geosciences from the Virginia Tech College of Science. “The oldest dinosaurs are known from roughly the same ancient latitudes along the southern temperate climate belt what was at the time, approximately 50 degrees south.”

Missing Middle bridged

Griffin and others from the Paleobiology and Geobiology Research Group at Virginia Tech purposefully targeted northern Zimbabwe as the country fell along this same climate belt, bridging a geographic gap between southern Brazil and India during the Late Triassic Age.

Moreover, these earliest dinosaurs were restricted by climatic bands to southern Pangea, and only later in their history dispersed worldwide. To prove the claim, the research team developed a novel data method of testing this hypothesis of climatic dispersal barriers based on ancient geography and the dinosaurian family tree. The breakdown of these barriers, and a wave of northward dispersal, coincided with a period of intense worldwide humidity, or the Carnian Pluvial Event.

After this, barriers returned, mooring the now-worldwide dinosaurs in their distinct provinces across Pangea for the remainder of the Triassic Period, according to the team. “This two-pronged approach combines hypothesis-driven predictive fieldwork with statistical methods to independently support the hypothesis that the earliest dinosaurs were restricted by climate to just a few areas of the globe,” Griffin said.

Brenen Wynd, also a doctoral graduate of 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 multitude of physical data from fossils, but also geochemical data that previously gave a really good idea of when major deserts were present,” he said.

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