Dinosaurs may have first evolved in the Sahara and Amazon rainforest

Dinosaurs may have first evolved close to the equator, not in the far south of the Southern Hemisphere as previously thought. A modeling study suggests that they originated in an area that now covers the Amazon rainforest, the Congo Basin and the Sahara desert.

“When you consider the gaps in the fossil record and the evolutionary tree of dinosaurs, this could potentially be a focal point for the origin of dinosaurs,” says. joel heath University College London.

Dinosaurs flourished sometime during the Triassic period, which lasted 252 to 201 million years ago, but Heath says there is “huge” uncertainty about where and when. The oldest known fossils of these animals are about 230 million years old, but they are distinct enough to suggest that dinosaurs had already existed for a few million years. “There must be a lot going on in terms of dinosaur evolution, but we don’t have the fossils,” he says.

The Earth looked very different at this time. All the continents were joined into a single continent called Pangea, which was shaped like a C and its central part was spread at the equator. South America and Africa were in its Southern Hemisphere section, where they fit together like jigsaw pieces. The earliest known dinosaurs are from the southern parts of those two continents, places like modern-day Argentina and Zimbabwe – so this was thought to be their place of origin.

To learn more, Heath and his colleagues created computer models to work backwards in time from the oldest known dinosaurs to the group’s origins. Taking into account uncertainties such as gaps in the fossil record, possible geographical constraints, and ongoing doubts about how early dinosaurs were related to each other, they created several dozen versions.

Most of these simulations concluded that dinosaurs first appeared near the equator, with only a minority supporting a southern origin.

Heath says paleontologists are beginning to believe that dinosaurs may not have originated near the equator, partly because there are no early dinosaur fossils in that area. More than that, it was a challenging place to live. “It was very, very dry and very hot,” he says. “It was thought that dinosaurs were not able to survive in those types of conditions.”

However, most models say otherwise. “It’s suggesting things that we didn’t really think were possible in the past,” Heath says.

Instead, a more likely explanation may be the lack of early dinosaur fossils from near the equator. Paleontologists have tended to excavate in North America and Europe, and later in China. “There are a lot of areas in the world that are quite neglected,” Heath says. He says geologists haven’t found many rocks of the right age that they can excavate in the areas related to the study’s findings. “They can’t be exposed in a way that we can easily study them.”

However, a piece of evidence in support of Heath’s idea has recently emerged. On January 8, researchers led david lovelace The University of Wisconsin-Madison reported that they found oldest known dinosaur From the northern part of Pangea. He discovered a species that is new to science called Ahavayatum sisterdoiveche, A sauropodomorph related to the long-necked dinosaur diplodocus Which developed later. The team found it in rocks of the Popo Ag Formation in Wyoming, dating back 230 million years.

If dinosaurs were to the north and south of Pangea so long ago, the equatorial middle could not have been closed off to them, Heath says. “They may be crossing that area.”