Discovery of the oldest dinosaurs in Africa

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An international team of paleontologists has discovered in the north of Zimbaue the fossils of the most ancient dinosaurs of Africa, among them the skeleton case complete of a new species of herbivore of cuello wide 1.8 meters long and between 10 and 30 kilos weight. These animals lived in the early Triassic, during the Carnian period, 230 million years ago. The discovery, published in Nature, suggests that the planet’s earliest dinosaurs were confined to a temperate region on the southern edge of the ancient supercontinent of Pangea.

dinosaurs

The remains are, according to the researchers, a real fossil treasure. Recovering such ancient dinosaurs is a real rarity which, until now, has only been achieved in a few places in the world, mainly in northern Argentina, southern Brazil and India. The fossils were found during two excavations conducted in 2017 and 2019. They included a herrerasaur dinosaur, relatives of ancient mammals such as cynodonts, relatives of armored crocodiles such as aetosaurs and “strange and archaic reptiles”. Rhynchosaurus.

But the most striking specimen is a new sauropodomorph, a long-necked dinosaur called Mbiresaurus raathi. According to the researchers, this dinosaur stood on two legs and its head was relatively small. It had small serrated teeth in the shape of a triangle, suggesting that it was a herbivore or potentially an omnivore.

“We did not expect to find such a complete and well-preserved dinosaur skeleton”recognizes Christopher Griffin, then at the Virginia Polytechnic Institute and State University (Virginia Tech) and now a researcher at Yale University, both in the United States. “When I found the femur of Mbiresaurus, I immediately recognized it as belonging to a dinosaur and knew that I had in my hands the oldest ever found in Africa. When I continued to dig and that I found the left hip bone right next to the left thigh bone, I had to stop and catch my breath; I knew that a large part of the skeleton was probably there, still articulated in a living position.”recount.

Diffusion through Pangea

The discovery of mbiresaurus led researchers to come up with a new theory about dinosaur migration. Africa, like all continents, was once part of the supercontinent called Pangea. The climate of Pangea is thought to have been divided into strong humid and arid latitudinal belts, with more temperate belts covering higher latitudes and intense deserts in the lower tropics. Scientists previously thought that these climatic belts influenced and restricted the distribution of animals in Pangea.

“Because dinosaurs initially dispersed under this climatic regime, early dinosaur dispersal should have been controlled by latitude.”points out Griffin. “The oldest dinosaurs are known at about the same latitudes along the southern temperate belt as they were then, around 50 degrees south.”, points out. Griffin and his team deliberately headed north from Zimbabwe as the country fell along this same climatic belt, bridging a geographic gap between southern Brazil and India during the late Triassic.

climate bands

Additionally, these early dinosaurs were limited by climatic bands south of Pangea, and only later in their history did they disperse across the globe. The breaking of these barriers and a wave of northward dispersal coincided with a global wet period, or the Carnian Pluvial Event, between 237 and 227 million years ago. After that, the barriers returned, “retaining” the dinosaurs in their various provinces across Pangea for the remainder of the Triassic period.

The authors suggest that climate controls influenced the early composition of terrestrial dinosaurs and other large groups⁠ such as mammals, turtles, amphibians and reptiles⁠, many of which persist to the present day.

Character font: JUDITH DE JORGE / ABC

Reference article: https://www.abc.es/ciencia/descubiertos-dinosaurs-ancient-africa-milliones-anos-20220831141005-nt.html

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