A recent study from the University College London (UCL) suggests that the first dinosaurs may have originated in the equatorial regions of Gondwana, covering territories that today correspond to the Amazon, the Congo Basin, and the Sahara Desert. This theory challenges previous models that pointed to a more southern origin, in areas such as Argentina, Brazil, and Zimbabwe.

New Perspectives on the Fossil Record

Scientists argue that dinosaurs may have appeared even before the oldest known fossils, which date back approximately 230 million years. To fill gaps in the fossil record, the researchers adopted an innovative approach: rather than interpreting fossil-free areas as places where dinosaurs did not live, they considered these regions unexplored. This implies that evidence of early dinosaurs might be hidden in hard-to-reach locations.

The Competition of the First Dinosaurs

The earliest dinosaurs were small, ranging in size from that of a chicken to a dog. In addition to being bipedal and omnivorous, they had to compete for space with much larger reptiles, such as pseudosuchians, which reached up to 10 meters in length, and pterosaurs, which dominated the skies. The rise of the dinosaurs only occurred after a massive extinction event caused by intense volcanic activity around 201 million years ago, which wiped out many of their competitors.

Expansion and Evolutionary Adaptations

Over time, dinosaurs spread from Gondwana to other continents, such as Europe, Asia, and North America. The researchers suggest that different groups developed specific adaptations to survive in various environments:

• Sauropods, like Brontosaurus, remained in regions with warmer climates.

• Theropods and ornithischians evolved to generate body heat, allowing them to inhabit cooler areas.

Implications for Dinosaur Evolution

The study also supports an intriguing hypothesis: silesaurids, previously classified only as close relatives of dinosaurs, may have been direct ancestors of ornithischians. If confirmed, this discovery would help fill a gap in the dinosaur evolutionary tree, explaining the absence of ornithischian fossils in the earliest periods.

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Want to dive deeper? Check out the full article published by UCL!