In the heat of southern Brazil, long before dinosaurs ruled the world, a small reptile wandered the land, oblivious to the history it was about to shape. Now, nearly 237 million years later, that creature’s fossil has resurfaced, offering scientists a rare glimpse into the dawn of the dinosaurs.

The dinosaur-like fossil, named Gondwanax paraisensis, represents one of the oldest known members of a mysterious group of reptiles called Silesauridae. About the size of a small dog, Gondwanax likely darted across the Triassic landscape, sharing its world with ancient turtles, frogs, and early mammals. Paleontologists now believe the fossil — one of the oldest of its kind ever found — could shed light into the evolutionary events that ultimately gave rise to the most fearsome creatures Earth has ever known.

Clues to the Dinosaur Dawn

In 2014, in the small town of Paraiso do Sul, Pedro Lucas Porcela Aurelio, a physician and lifelong fossil enthusiast, stumbled upon a fossil embedded in ancient rock. He had no idea at the time that he was holding a piece of prehistory that dated back nearly a quarter of a billion years. Aurelio donated the fossil to a local university in 2021.

Rodrigo Temp Müller and his team at the Federal University of Santa Maria slowly chipped away at the mystery. They soon realized they were looking at an animal that stood on the cusp of something extraordinary.

“It’s an indescribable feeling,” Aurelio told Reuters. “Being the first human to touch something from 237 million years ago is extraordinary.”

Gondwanax was no more than a meter (3.3 ft) long, with a long tail and a lightweight body, perfect for a life on the move. Its bones, though small, spoke volumes. One of the most striking features Müller’s team uncovered was the presence of three sacral vertebrae, a trait seen in more advanced dinosaurs, hinting that this humble reptile might have been experimenting with new ways to move.

“The most important part of this finding is its age,” Müller said. “Because it’s so old, it gives us clues as to how dinosaurs came to be.”

Silesaurids like Gondwanax occupy a strange, debated space in the reptilian family tree. While some researchers argue they were true dinosaurs, others believe they were more like evolutionary cousins — close relatives who shared the Triassic world but didn’t survive into the dinosaur era. Either way, their importance can’t be overstated. These were animals that lived in a world that was rapidly changing, a time when the first true dinosaurs were emerging.

For over 30 million years, the Silesauridae thrived across the Triassic landscapes, occupying a variety of ecological niches. Gondwanax lived in what was then part of the southern supercontinent Gondwana, its very name — “lord of Gondwana” — a nod to that ancient land.

Müller’s team also discovered that Gondwanax shared its environment with another reptile, Gamatavus antiquus, marking the oldest known example of sympatry, where two species coexist.

This diversity in early locomotion and lifestyle hints at something fascinating — evolutionary experimentation. “The unique combination of sacral and hindlimb features may suggest distinct behaviors for these species, potentially leading to niche differentiation,” Müller said in a press statement.

A Prehistoric Puzzle

Yet, for all the excitement surrounding this fossil, Gondwanax raises as many questions as it answers. Silesaurid fossils are rare, often incomplete, leaving scientists with only fragments of these creatures’ lives. Müller acknowledged that “there are several aspects of the anatomy of silesaurids that are obscure or poorly investigated.”

Still, the fossil’s discovery has added a new layer to our understanding of the Triassic period — a time when the blueprint for dinosaurs was just starting to be drawn.

“We are only beginning to understand how these ancient creatures lived and evolved,” Müller said. “But this discovery gives us one more clue as to how the story of dinosaurs began.”

So far, what Gondwanax and its fellow silesaurids reveal is that the rise of the dinosaurs wasn’t a sudden, dramatic event. Instead, it was a slow, steady evolution, filled with false starts and subtle adaptations.

The findings appeared in the journal Gondwana Research.