A fossil find from the dusty soils of Argentina is rewriting what we thought we knew about how snakes lost their legs — thanks to a sharp-eyed paleontology student and a skull that survived 95 million years.

A Student’s Lucky Break in the Field

It started with a routine field trip in February 2013. Fernando Garberoglio, then an undergrad at Universidad de Buenos Aires, was poking through the rock layers in the Río Negro Province.

Then he spotted it — a skull, more intact than anything found before.

Imagine the rush: you’re 21, still figuring out if your degree will land you a job, and suddenly you’re holding a key that could unlock secrets of an entire species.

Garberoglio and his professors knew immediately it was something special.

Meet Najash: The Snake With Legs

Scientists had known about Najash rionegrina since the early 2000s, when a fragmented skull and partial skeleton turned up. Even that rough evidence was enough to rattle the field — here was proof that not all ancient snakes slithered the same way.

Najash takes its name from the Hebrew word nahash, meaning snake — a nod to the legged serpent in the biblical Eden story.

This fossil? It confirmed what earlier scraps hinted at: Najash was a land-based snake that still sported hind limbs. Unlike marine snakes like ancient mosasaurs, Najash roamed dry land, its tiny legs flanking a long, flexible body.

Why This Skull Matters

It might seem like a small detail, but the new skull made all the difference.

As Alessandro Palci and Michael Caldwell, the lead researchers alongside Garberoglio, explained, it’s the first full 3D skull ever found for a terrestrial snake with hind legs.

It shows exactly how the jaws hinged.
It shows how the braincase evolved.
It shows where the skull fused and where it didn’t — basically, a blueprint of evolution frozen in time.

Palci summed it up: “This discovery fills a gap we’ve been puzzling over for decades.”

Snakes With Legs? Believe It

If you’re picturing a snake doing a tiny four-legged trot, not quite. Najash’s limbs were small and stubby, likely not much help for walking.

But they weren’t useless stumps either — they may have helped with mating or maneuvering through brush.

A quick rundown of what sets Najash apart:

• Hind legs: Small but well-formed, unlike modern snakes.

• Terrestrial: Not marine, unlike earlier leggy snake fossils.

• Full 3D skull: Preserved in remarkable detail.

These traits make Najash a unique evolutionary stopover between lizards and the slinky, legless serpents we know today.

A Look at Snake Evolution

The big question: When did snakes lose their legs for good?
Najash helps connect the dots.

Here’s a simple snapshot:

Source: Caldwell & Palci, 2025

Najash lived well after Pachyrhachis, a marine snake with hind limbs. But Najash’s land-loving ways prove that legged snakes didn’t all evolve underwater. Some crawled through scrubland, legs and all.

“A Window Into the Past”

For paleontologists, fossils like this don’t come around often.

Caldwell described it as “a window into an ancient world — like peering through a crack in the rock to see what life was experimenting with.”

Back then, the world was warm. Dinosaurs roamed South America, crocodile-like reptiles lurked in rivers, and creatures like Najash wriggled through dry brush, half-lizard, half-snake.

Lessons for the Future of Fossil Hunting

Garberoglio’s find is a reminder that young scientists can make huge contributions — you don’t need to be a tenured professor to shake things up.

His advice to other students?
“Don’t be afraid to get dirty. And don’t overlook the small stuff. Sometimes it’s the tiny bones that tell the biggest stories.”

One dig, one skull, and suddenly textbooks have to change.