Scientists Uncover Dinosaur Origins in the Tropics of Gondwana

Groundbreaking research suggests dinosaurs may have first evolved in the tropical regions of Gondwana, including the ancient Amazon basin.

There’s no doubt this: Dinosaurs are some of the most fascinating creatures ever roamed Earth. These mighty giants have inspired generations in all fields, from scientific discovery to visual and writing arts. 

I bet it’d be hard to find someone who can’t name at least one dinosaur species. However, very few know about the story of how they came to be. Where did their incredible story begin? 

For years, we have debated whether dinosaurs originated in southern regions of Gondwana (an ancient supercontinent that encompassed what we now know as modern South America and Africa) or elsewhere. Indeed, understanding their origins can offer important clues about how evolutionary processes work, so I’ve seen many conference talks debating this. 

However, a recent study led by researchers from University College London takes a fresh approach to this question and proposes a less considered possibility: the earliest dinosaurs may have emerged in the tropical regions of Gondwana, including what we now know as the Amazon, Congo Basin, and the Sahara Desert.

But why is this surprising to us paleontologists?

Well, the oldest known dinosaur fossils, dated to about 230 million years ago, have been found in Argentina, Brazil, and Zimbabwe. Yet their diversity and evolutionary traits hint at an even earlier origin. 

This study used advanced modeling techniques to reassess the origins of dinosaurs, accounting for gaps in the fossil record and the evolutionary connections between dinosaurs and their reptilian relatives.

I know, lots of fancy words, but let’s look at how these paleontologists performed the study to understand their reasoning better. 

The researchers used biogeographic models (which consider geography and biological species) that did something crucial for the results: They factored in missing data. This means that they treated regions where we don’t have fossils as not as devoid of fossils but as unexamined territory. 

In other words, regions where we haven’t done enough fieldwork or where the geological elements (i.e., erosion) have already destroyed them, preventing us from finding new fossils. 

The team combined these models with evolutionary trees and geological data to reconstruct likely habitats and conditions where dinosaurs first emerged. 

Lead author Dr. Joel Heath explained, “Our modeling suggests that the earliest dinosaurs might have originated in western, low-latitude Gondwana. This is a hotter and drier environment than previously thought, made up of desert- and savanna-like areas.”

But the study wasn’t blindsided, they also explored alternative evolutionary scenarios by including silesaurids, a group previously thought to be dinosaur cousins, as potential ancestors of early dinosaurs. This helped to address gaps in the evolutionary tree and rule out alternative hypotheses. 

And what did all these fancy methods tell about the dinosaur’s story?

Well, the results strongly support a low-latitude Gondwanan origin for dinosaurs, challenging earlier ideas that placed their beginnings in mid-latitudes, farther away from the equator. 

The evidence suggests that dinosaurs first thrived in hot, arid conditions, navigating landscapes dominated by deserts and savannas. Think of the Sahara and the Sahel. Based on fossil findings, we know that this tropical zone was home to a mix of reptiles, including early pseudosuchians, the ancestors of crocodiles, and the first flying reptiles, pterosaurs. 

Back then, dinosaurs were relatively small and unassuming by comparison, with early species like Eoraptor and Herrerasaurus roughly the size of a chicken or dog.

Senior author Dr. Philip Mannion noted, “Our results suggest early dinosaurs may have been well adapted to hot and arid environments.” 

Over time, dinosaurs spread across Gondwana (the southern supercontinent we talked about) and into the northern supercontinent Laurasia, which included Europe, Asia, and North America. As dinosaurs expanded, they diversified into various ecological niches, setting the stage for their domination of terrestrial ecosystems in the Jurassic and Cretaceous.

Well, now that we know what they found, it’s time to ask what this all means to dinosaur evolution. 

One key takeaway is the importance of looking at the big picture when interpreting the fossil record. The study highlights how gaps in our understanding of early dinosaur evolution may be due to limited sampling in regions like the Amazon and Congo Basin. These areas, though challenging to explore, could hold vital clues to the earliest stages of dinosaur history. 

Dr. Heath pointed out, “This might be because researchers haven’t stumbled across the right rocks yet due to a mix of inaccessibility and a relative lack of research efforts in these areas.” Indeed, sampling bias could be playing a trick on us. 

What Lessons can we learn from this Deep Time story? 

Well, this study doesn’t just offer a new perspective on where dinosaurs came from; it also reminds us how little we truly know about their early days and how much remains unexplored. 

The challenges of accessing remote fossil sites, combined with the uneven distribution of preserved remains, mean that the story of dinosaurs’ origins is far from complete — which, as a paleontologist, sounds exciting. 

The good news is that by integrating modeling techniques and expanding exploration into underrepresented regions, researchers can continue uncovering the secrets of these ancient creatures.

Dinosaur’s adaptability to warmer and more arid conditions may have been the foundation for their later success as they spread across the globe. It’s a reminder that evolution often begins in unexpected places and that the full story may lie just beyond the edge of what we currently know.