Scientists Discover ‘Living Fossil’ With One of the Strangest Jaws They’ve Ever Seen
A prehistoric creature found near the Amazon rainforest in Brazil had a jaw so bizarre that researchers initially thought they were looking at damaged fossils.
After years of analysis, the animal turned out to be an entirely new species — one that lived millions of years longer than scientists believed possible for its kind.
The species is called Tanyka amnicola, a name that roughly translates to “jaw living next to the river.”
It lived about 275 million years ago during the Early Permian Period and belonged to a group called stem tetrapods, early relatives of modern four-limbed animals that eventually gave rise to the ancestors of amphibians, reptiles, birds and mammals.
Most stem tetrapods went extinct long before Tanyka lived. The species persisted well past the point scientists expected any animal like it to survive, retaining primitive traits even as more advanced animals evolved around it.
“Tanyka is a little like a platypus, in the sense that it was a member of the stem tetrapod lineage that remained even after newer, more modern tetrapods evolved,” lead author Jason Pardo said, per the Natural History Museum. “It was a living fossil in its time.”
A Jaw That Drove Scientists ‘Crazy’
The defining feature of Tanyka amnicola is its jaw, and it worked on a completely different principle than what you’d find on any familiar animal.
Most tetrapods have teeth that face each other in the upper and lower jaws, a setup that allows animals to slice, cut and grind food. Tanyka’s lower jaw twisted outward from back to front.
Some teeth pointed outward and sideways rather than toward the opposing jaw. And lining the inside of the jaw were small grinding teeth called denticles.
If you were to run your tongue over the teeth on your lower jaw, you would feel the tops of your teeth facing up towards the roof of your mouth.
In Tanyka, the twisted lower jaw meant the teeth were pointed out to the sides. The part of the jawbone that normally faces the tongue is pointed upwards.
Researchers believe the denticles in the upper and lower jaws likely rubbed together to grind food.
Based on this jaw structure, the animal’s possible diet included tough plant material and small invertebrates with hard shells. That suggests Tanyka may have been omnivorous or herbivorous — a departure from many of its meat-eating relatives.
“It’s a really strange animal, and the weird twist in the jaw drove us crazy trying to figure it out. But nine jaws we’ve found have this twist, including the really well-preserved ones, so it’s not a deformation. It’s just the way this animal was,” Pardo added.
How a Confusing Fossil Became a New Species
The path from fossil fragment to published species took some unexpected turns.
Researchers initially found one twisted jawbone during excavations. They suspected it might be damaged or deformed. They also thought it belonged to a fish.
“At first, we wondered if these fossils might be the remains of a fish,” co-author Martha Richter said, per the NHM. “It was only once the fossils were properly prepared in the lab that the true nature of Tanyka was clearly revealed to us.”
Over time, the team discovered eight more jawbones with the same twist.
That repeated pattern across nine total specimens confirmed that the twisted jaw was a natural anatomical feature, not damage or distortion from the fossilization process.
“By comparing its anatomical traits to the characteristics of known species from across hundreds of millions of years, we found that this animal was actually a primitive tetrapod after all,” Richter added.
The study describing the species was published in the journal Proceedings of the Royal Society B.
What Researchers Think It Looked Like
Scientists are uncertain about the full body shape because only jaw fossils have been definitively linked to the species.
Researchers believe it likely resembled a salamander-like animal with a longer snout. Other nearby fossils may belong to the same species, but this has not yet been confirmed.
That means the jaw is, for now, the entire window into what Tanyka was. Nine bones carrying the full weight of a species description.
Scientists long believed stem tetrapods largely disappeared after a major ecological event known as the Carboniferous Rainforest Collapse.
That event caused widespread destruction of tropical forests and loss of the humid environments many early tetrapods relied on. The assumption: these animals couldn’t survive without those conditions.
Tanyka lived about 275 million years ago, well after that collapse. Its existence in what is now Brazil suggests some stem tetrapods survived much longer than scientists thought.
During the time Tanyka lived, Earth’s land was joined into the supercontinent Pangaea. The climate in the region where the fossils were found was likely hot and seasonally dry.
One possible explanation for the species’ survival: animals in the southern part of Pangaea may have experienced different climates than those in the north, and those conditions may have allowed them to persist after northern populations went extinct.
The finding raises the question of what else might be waiting in underexplored fossil sites across the Southern Hemisphere.
Production of this article included the use of AI. It was reviewed and edited by a team of content specialists.
