Recent research led by University College London indicates that the remains of the earliest dinosaurs may be buried in the Amazon and other equatorial regions of South America and Africa, awaiting discovery. The study, published in Current Biology, aims to reconstruct the evolution of dinosaurs based on fossil findings, the genealogies of their closest relatives, reptiles, and the geography of that era when land masses formed the supercontinents Gondwana in the south and Laurasia in the north.
According to researchers, no fossils have emerged from these regions due to a combination of inaccessibility and a lack of research. Currently, the oldest known dinosaur fossils date back approximately 230 million years and have been discovered in areas such as Brazil, Argentina, and Zimbabwe. However, these creatures likely originated millions of years earlier. The earliest specimens were significantly smaller than their descendants, roughly the size of a chicken or dog, walked on two legs, and were predominantly omnivorous. Initially, they were numerically inferior to their reptilian cousins but became dominant around 201 million years ago, following massive volcanic eruptions that wiped out many of their relatives.
Researchers led by Joel Heath developed models accounting for gaps in the fossil record. These simulations suggest that the origin of the first dinosaurs may have occurred in warm, dry areas of the western part of the Gondwana supercontinent, which later formed the Amazon, the Congo Basin, and the Sahara Desert. This region was approximately midway between southern Gondwana, where the oldest fossils were found, and Laurasia, where many of their close relatives' remains were discovered.