Scientists have figured out how and when dinosaurs spread across the Earth

After the Triassic-Jurassic extinction event, which occurred 201 million years ago, dinosaurs became the dominant species on Earth. But where did they originate and how did they spread throughout the Earth? Presumably this happened between 243 million and 233.23 million years ago, but there was no exact data on this until the last moment, and even more so it was not known where the first dinosaurs arose.

The situation was clarified thanks to the fossils of the dinosaur Mbiresaurus raathi discovered in Africa, which are 230 million years old. It is one of the earliest known ancestors of the sauropods, a group that includes the legendary long-necked herbivorous giants such as Brachiosaurus and Brontosaurus. In addition, mbiresaurus turned out to be the most ancient dinosaur discovered in Africa. But what else did scientists manage to find out by studying the structure of the skeleton of this fossil animal?

Africa’s oldest dinosaur – what was it  like?

Easily recognizable by their long necks, sauropods were the largest animals that ever lived and walked on land. Some of them were the size of a high-rise building. However, their ancient ancestor had a more modest size, as scientists report in the journal Nature. Its height at the hip was about half a meter. It had a small head and a relatively short neck.

I must say that the fossils of Mbirezavr are perfectly preserved. And it was possible to find almost all the bones of the skeleton. Only a few vertebrae are missing, as well as the bones of the hand, ankle, and some parts of the skull. Separate parts of the skeleton were even articulated, as it was during the life of the animal.

Mbirezaur fossils are perfectly preserved

According to scientists, one of the key features of the dinosaur skeleton, by which scientists can determine the lineage of the dinosaur and the age of its species, is located in the hip joint. The femur of Mbiresaurus is shaped like that of the earliest species. This allows the animal to be placed at the base of the dinosaur family tree.

When and where did dinosaurs appear

The fossil finds that scientists have been able to accumulate over the past decades indicate that dinosaurs appeared on our planet 245 million years ago. But, then they were not as huge as in the Jurassic period. Recall that at this point in time there was a single supercontinent Pangea, which was washed by the superocean.

But where exactly did dinosaurs originate? As you know, Africa is the cradle of mankind, in addition, many other species originated here. However, there was no data regarding the African origin of dinosaurs. But now the presence of fossils of the earliest dinosaurs in Africa has shown that these animals originated here.

Scientists have discovered in Zimbabwe a lot of fossils of the leaves of various plants of the Triassic period

The study of the Mbiresaur fossils also made it possible to find out what was the ecosystem in which the dinosaur lived. As it turned out, its habitat had a meandering river system with a fairly fast flow, as a result of which the Pebbly-Arcose Formation has a large amount of pebbles, that is, in those rock layers in which the Mbiresaur was found.

The area was also rich in lush plants, which served as food for many herbivores and omnivores of that time. But carnivorous dinosaurs also lived along with herbivores, as evidenced by several herrerasaurid bones, which were also found in the Pebbly Arcose Formation.

When did dinosaurs spread around the world?

Based on the fossils of Mbirezavr and other dinosaurs of the Triassic period, found in different parts of the planet, scientists came to the conclusion that the first dinosaurs did not leave their habitat for a long time. Their expansion to the north began only 230 million years ago, that is, 15 million years after the appearance of the first dinosaurs.

Theropods were the first to migrate north 230 million years ago.

Theropods were the first to migrate, a group of dinosaurs that later gave rise to bipedal predators such as Tyrannosaurus Rex, as well as modern birds. About 220 million years ago they were followed by sauropodomorphs.

This period is in good agreement with climate changes in the Triassic period. Between 235 and 230 million years ago, the Earth is known to have experienced a couple of million years of heavy rainfall and high humidity. This period is called the Carnian pluvial event. During this time, the tropical deserts of Pangea shrank and became covered with vegetation, which may have given dinosaurs the opportunity to migrate to new areas.

It must be said that Pangea did not have barriers in the form of giant mountain ranges. The obstacles were only climatic. The polar regions were, as we said above, lush vegetation, and the tropical belts north and south of the equator (before the onset of the Carnian pluvial event) were harsh: hot, arid and prone to fires.

Currently, scientists are studying other fossils found in Africa. Presumably, all of them also belong to previously unknown species. Perhaps soon scientists will have even more information about the early Earth.