The remains of the first dinosaurs could lie undiscovered in the Amazon and other equatorial regions of South America and Africa, suggests a modeling study led by researchers at University College London, which also points to a origin millions of years earlier.
Currently, the fossils dinosaur oldest that are known date back a few years 230 million years and they were unearthed further south, in places like Brazil, Argentina and Zimbabwe. But the differences between these fossils suggest that dinosaurs had already been evolving for some time, pointing to an origin millions of years earlier, the researchers say. Work, according to the British university (UCL), is a “new twist on the mysterious origin of dinosaurs”; the results are published in the journal Current Biology.
This has taken into account the Existing gaps in the fossil recordconcluding that the first dinosaurs probably arose in a warm equatorial region on what was then the supercontinent Gondwana. This area of land today covers the Amazon, the Congo basin and the Sahara desert, explains a statement from UCL.
“Dinosaurs are well studied, butWe still don’t really know where they come from. The fossil record has gaps so large that it cannot be taken literally,” says Joel Heath. “Our model suggests that the first dinosaurs could have originated in Gondwana, a low-latitude western area. “It is a warmer and drier environment than previously thought, made up of desert areas and savannahs,” he adds.
So far, no fossils have been found in the regions of Africa and South America that once formed this part of Gondwana. However, “this could be because researchers haven’t stumbled upon the right rocks yetdue to a mixture of inaccessibility and relative lack of research efforts in these areas.”
Much smaller
The modeling study was based on fossils and evolutionary trees of dinosaurs and their close reptile relatives, as well as in geography of the time. At first, the first dinosaurs were vastly outnumbered by their reptilian cousins, including the ancestors of crocodiles, the pseudosuchians (a large group that included enormous species up to 10 meters in length).
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 omnivores. They became dominant after volcanic eruptions wiped out many of their reptilian relatives 201 million years ago.
The new results suggest that dinosaurs and other reptiles could have originated in Gondwana low latitude, before radiating southwards and Laurasia, the adjacent northern supercontinent that later divided into Europe, Asia, and North America. This origin is supported by the fact that it is an intermediate point between the place where the first dinosaurs have been found in southern Gondwana and where the fossils of many of their close relatives have been discovered to the north, in Laurasia, emphasizes the university. .
The researchers tested their model with three proposed evolutionary trees. The model that considered the silesauridstraditionally considered cousins of dinosaurs but not dinosaurs themselves, such as ancestors of ornithischian dinosaurs was the one that most supported the Gondwanan origin of dinosaurs at low latitude.
The ornithischians, one of three major groups of dinosaurs that later included the plant-eaters Stegosaurus and Triceratops, are mysteriously absent from the fossil record of these first years of the age of the dinosaurs. If silesaurids are the ancestors of ornithischians, this helps fill this gap in the evolutionary tree.
“The ultimate test of our models will be whether early dinosaur remains are found in the Amazon, the Sahara Desert and other ancient low-latitude parts of Gondwana,” Heath says. “Finding them would revolutionize our understanding of ecosystems of the Triassic and would offer key information about the evolutionary history of the group,” adds a note from the Natural History Museum.
#twist #mysterious #origin #dinosaurs #older #specimens #undiscovered
