Dinosaurs Originated in the Amazon, New Study Suggests

Dinosaurs may have originated in the warm, tropical regions of Gondwana, the ancient supercontinent that now includes parts of the Amazon, and various other areas in the Southern Hemisphere.

The study published in Current Biology by researchers from University College London (UCL) suggests that some of the earliest dinosaur fossils may still lie undiscovered.

These findings challenge long-standing assumptions about the origin of dinosaurs and shed new light on their early evolution.

Fossil evidence points to an earlier origin

The oldest known dinosaur fossils, dating back 230 million years, have been found in places such as Brazil, Argentina, and Zimbabwe. However, variations among these fossils suggest that dinosaurs had already been evolving for millions of years before that time.

Researchers believe this indicates their origins may date back even further, potentially in areas yet to be explored.

Where did the first dinosaurs evolve? Scientists may have found the location

Dinosaurs likely originated in a locale that spans the modern-day Sahara desert and Amazon rainforest regions, study suggests. pic.twitter.com/1lZ0GCwL5Q

— AI Day Trading (@ai_daytrading) January 24, 2025

The study’s lead author, UCL Earth Sciences doctoral student Joel Heath, explained that fossil record gaps make it difficult to pinpoint where dinosaurs first appeared. “Although dinosaurs have been widely studied, we still don’t really know where they came from,” he said.

Early life in Gondwana

Using models to account for these gaps, the researchers theorized that dinosaurs first emerged in the low-latitude regions of Gondwana.

These areas, now part of South America, Africa, and portions of the Middle East, were warm and arid during the Triassic period, featuring deserts and open grasslands.

No fossils from these specific equatorial regions have been discovered yet. This is likely due to the challenging conditions for exploration and the limited scientific studies in these remote areas.

Small beginnings in a competitive world

Dinosaurs were small, bipedal creatures when they first appeared, roughly the size of a chicken or a dog. Most were omnivorous, which means being able to eat both plants and meat, helping them adapt to their environments.

Despite their adaptability, they were not the dominant animals of their time. Larger reptiles, such as pseudosuchians – ancestors of crocodiles that could grow up to 10 meters long – were more common. Flying reptiles like pterosaurs also thrived, some with wingspans as large as modern fighter jets.

The rise of dinosaurs

The dinosaurs’ dominance began around 201 million years ago, following a series of massive volcanic eruptions. These events wiped out many of their reptilian competitors, allowing dinosaurs to take their place.

Why did pseudosuchians go extinct?

Around 201 million years ago, volcanic activity or a meteor killed off half the known species on Earth. Just one lineage of pseudosuchians, called the crocodylomorphs, survived. That branch would ultimately give rise to modern-day crocodiles. pic.twitter.com/Zgrj8OhcBd

— LEVI MCCOOL STRAUSS-GUITAR-GUITAR-GUITAR-GUITAR (@Poverty_Suckz) April 10, 2024

The study also explored a possible evolutionary link between silesaurids—reptiles considered relatives of dinosaurs—and ornithischians, a group of plant-eating dinosaurs that includes Triceratops and Stegosaurus. This discovery could help fill the gaps in the dinosaur family tree and provide new insights into their evolution.

Adapting to cold climates

Study co-author Professor Philip Mannion noted that early dinosaurs were likely suited to warm, dry climates.

Sauropods like Diplodocus remained in these regions, while theropods and ornithischians later developed the ability to generate body heat. This adaptation allowed them to survive in colder climates, eventually reaching polar regions.

The study highlights there is much more to learn about dinosaur origins, suggesting untapped potential for discovery in unexplored regions of the world.