The family album of the oldest dinosaurs in the world, in which even today species from Brazil and Argentina prevail, has acquired new members: the first African cousins.
At 230 million years old, the same age as their South American relatives, fossils from Zimbabwe are an important piece to understanding how dinos began their evolutionary journey.
According to the new study on the topic, which appears in this week’s issue of the scientific journal Nature, the genesis of dinosaurs was marked by the very different layout of the continents at the time.
By the way, it is more appropriate to use the singular: there was only one giant continent, called Pangea, which means that Africa and South America formed a continuous land mass from west to east, without the Atlantic Ocean between them.
In addition, and most importantly, the areas inhabited by the first dinosaurs were not tropical and subtropical, as in today’s Zimbabwe and Rio Grande do Sul, where their fossils have been found.
The order of the supercontinent meant, at the time, that these regions were at a latitude of about 50 degrees in the Southern Hemisphere—that is, in a temperate zone, equivalent to the location of London or Paris in the modern northern hemisphere. Globalism.
Practically speaking, the oldest dinosaurs seem to have spent several million years confined to this temperate group of Pangea, which also stretched eastward as far as India.
And this is for good reason: the climate of the Triassic period, when the group appeared, turned the tropics, closest to the equator, into enormous deserts. Therefore, dinosaurs would have been confined to their temperate cradle in the Southern Hemisphere, where they are more humid and pleasant.
The work, to be released in Nature, was signed by an international team including Christopher Griffin, of Virginia Tech (USA), Darlington Muniqua, of Zimbabwe’s Natural History Museum, and Brazilian Max Cardoso Langer, of the University of the South Pacific in Ribeirao Preto, of among other researchers.
The team described the oldest African dinosaurs, which were given the scientific name hereditary meperisaurus. This animal is a primitive member of the sauropodomorph group – the same thing that, tens of millions of years later, would end up harboring the largest land animals of all time, such as the famous Brontosaurus.
a M. hereditaryHowever, it was only two meters tall and weighed a maximum of 30 kg. With about 90% of its skeleton preserved, the animal was bipedal and had small, toothy, triangular-shaped teeth, probably suitable for an herbivorous diet.
In fact, all of these characteristics are very reminiscent of the sauropodomorph of the old guard that roamed what would one day be inside Rio Grande do Sul at the same time, such as Saturnalia it’s the pampadromaeusboth described by Langer and placed near a new African species in the dinosaur family tree.
The team also identified segmented fossils of a much larger carnivorous dinosaur of the herrerasaurid group, which could have been up to six meters long.
“It’s another sign that they are dinosaurs very similar to those of South America at the same time, with herbivores between small to medium in size and large carnivores,” Langer said. “It’s an interesting thing to see from an ecological point of view.” to me binding.
According to him, it is not clear whether the initial diversification of dinosaurs in the temperate and humid regions of the Southern Hemisphere was a direct result of these climatic conditions or whether, at first, it was just a historical accident of the evolution of the group.
In any case, everything indicates that the animals were only able to cross the tropics and reach the northern hemisphere after millions of years, thanks to the so-called “Carnian-Bluval event”, when humidity increased globally (Carnian is the period in which the group appears and varies between 237 million years and 227 million years ago).
“After this event stops, the separation takes place. [entre as linhagens do hemisfério Norte e do hemisfério Sul]but then the animals were already there,” concludes the Brazilian paleontologist.
From there, the era of the dinosaurs became increasingly globalized.
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