A small dinosaur the size of a chicken, but with a rather long name Ahvaytum bahndoivechehas become the oldest known dinosaur in Laurasia, so experts believe it lived in a period similar to the dinosaurs of Gondwana, which until now were considered the world’s first dinosaurs.
The remains of several individuals of the new species were first discovered in 2012 in the Popo Formation Agie in the state of Wyoming. Among his remains were leg bones, from a Silesáurid dinosaur about 30 centimeters high and 90 cm long, which was probably an adult when it died.
New studies on dinosaurs
The remains of the first dinosaurs could have lain undetected in the Amazon and other equatorial regions of South America and Africa, a study suggests Modeling study Directed by researchers from University College London, which also points to a previous million years.
Currently, the oldest dinosaur fossils known date from about 230 million years ago and have been unearthed further south in places like Brazil, Argentina and Zimbabue. But the differences between these fossils suggest that dinosaurs had been evolving for some time, An origin focused a million years earlierthe researchers point out. The work is a “new twist in the mysterious origins of dinosaurs” according to the British University (UCL); The results are published in the journal Current biology.
This has been taken into account Supercontinent Gondwana. This land area today covers the Amazon, the Congo Basin and the Sahara Desert, a UCL statement explains.
Great lagoons in the records
“Dinosaurs are well studied, but we still don’t really know where they came from. The fossil record presents lagoons so large that it cannot be brought to the letter,” he says Joel Heath. “Our model suggests that the first dinosaurs may have emerged in Gondwana, a low-latitude western region. It’s one warmer and dry environment From what was thought, formed by desert and savannah areas,” he adds.
So far, fossils have not been found in the regions of Africa and South America that formed this part of Gondwana. “However, this may be due to the fact that researchers have not yet come across the right rocks, due to a mixture of inaccessibility and relative lack of research efforts in these areas.” The study Modeling was based on fossils and evolutionary trees of dinosaur and reptilian relatives Close, as well as in the geography of the time.
In the beginning, the first dinosaurs were widely conquered by their reptilian couss, including the Crocodile ancestorsthe pseudosuquios (an abundant group with enormous species up to 10 meters long).
The first dinosaurs were much smaller than their descendants, More the size of a chicken or a dog than a diplodocus. They walked on two legs and it is believed that most were omnivorous. They became dominant after volcanic eruptions wiped out many of their reptilian relatives 201 million years ago.
¿Gond-friend?
The new results suggest that Dinosaurs and other reptiles could have originated in Gondwana From low latitude, before the irradiation of the south and Laurasia, the adjacent northern supercontinent later divided into Europe, Asia and North America.
This origin is based on the fact that it is an intermediate point between where the first dinosaurs were found in southern Gondwana and where They have discovered the fossils of many of their relatives near the north, in Laurasiaemphasizes the university.
The researchers tested their model with three proposed evolutionary trees. The model that considered the Silesáuridos, traditionally considered cousins of the dinosaurs, but not dinosaurs themselves, as ancestors of the ancestors of the Ornitisquios dinosaurs was the one that most supported the Gondwanic origin of dinosaurs at low latitudes.
Ornitisquios, one of the three main dinosaur groups that later became the Stegosaurus and Triceratops Plant dining roomsthey are mysteriously absent from the fossil record of these early years of the dinosaur era. If the Silesáurids are the ancestors of the ornitisquios, this helps fill this void in the evolutionary tree.
“The definitive proof of our models will be if there are remains of primitive dinosaurs in the Amazon, the Sahara Desert and other low-latitude ancient parts of Gondwana,” says Heath. «Finding them would revolutionize our understanding of Triassic ecosystems And he would provide important information about the group’s evolutionary history,” adds a note from the Natural History Museum.