Picture this: you’re a scientist digging near the Amazon rainforest, and you pull a jawbone out of the ground that looks so wrong you assume it broke underground.
Then you find another one. Same weird twist. Then another. And another. Nine total, each with the same baffling shape.
That’s exactly what happened to a team of researchers who just identified one of the strangest ancient creatures ever discovered — and it’s rewriting textbooks in the process.
The animal? Tanyka amnicola, which translates roughly to “jaw living next to the river.”
It lived about 275 million years ago, and its discovery has scientists rethinking some very confident assumptions about when certain ancient creatures disappeared from the planet.
Tanyka Amnicola Is the New Species That Started With One ‘Weird’ Fossil
The way Tanyka came to light is a story worth telling. Researchers found a single twisted jawbone during excavations in Brazil.
Their first instinct? Something must have gone wrong. Maybe the fossil was crushed during its 275 million years underground. They also thought it belonged to a fish, not a land-dwelling creature.
“At first, we wondered if these fossils might be the remains of a fish,” coauthor Martha Richter recalls, per the Natural History Museum. “It was only once the fossils were properly prepared in the lab that the true nature of Tanyka was clearly revealed to us.”
Then the team kept digging and found eight more jawbones with that same twist. One oddly shaped jaw could be a fluke. Nine? That’s a pattern.
“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,” lead author Jason Pardo added.
The repeated structure confirmed the twisted jaw was a natural anatomical feature. And after comparing its traits to known species spanning hundreds of millions of years, the team realized they had something unexpected on their hands.
“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 was published in the journal Proceedings of the Royal Society B.
What Made Tanyka Amnicola’s Jaw So Unique?
Most tetrapods (the group that includes four-limbed animals) have teeth in the upper and lower jaws that face each other. This lets animals slice, cut, and grind food. You can see the setup in everything from a house cat to a crocodile.
Tanyka’s mouth threw out that entire playbook.
Its lower jaw twisted outward from back to front. Some teeth pointed outward and sideways rather than inward toward the opposing jaw.
And lining the inside of the jaw were small grinding teeth called denticles. Researchers believe the denticles in the upper and lower jaws likely rubbed together to grind food — almost like a built-in mortar and pestle.
Vitor Silva, Field Museum
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.
This unusual setup suggests a possible diet of tough plant material and small invertebrates with hard shells, which would make Tanyka omnivorous or herbivorous. That’s a departure from many of its meat-eating relatives.
Researchers described the species as belonging to a more experimental stage in early animal evolution, when nature was still trying out different designs for how a mouth could work.
Only jaw fossils have been definitively linked to the species, so scientists aren’t certain about its full body shape. They believe it likely resembled a salamander-like animal with a longer snout. Other nearby fossils may belong to the same species, but that hasn’t been confirmed yet.
Think of the Tanyka Amnicola as the Platypus of 275 Million Years Ago
The researchers themselves offered an analogy that makes Tanyka’s place in its world click: think of the platypus.
That odd, duck-billed, egg-laying mammal looks like it belongs to a much earlier chapter of evolution, yet it persists today alongside far more modern creatures.
Tanyka had a similar vibe. It 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.
But most stem tetrapods went extinct long before Tanyka lived.
“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,” Pardo said. “It was a living fossil in its time.”
Tanyka lived during the Early Permian Period, when Earth’s land was joined into the supercontinent Pangaea. The climate where the fossils were found was likely hot and seasonally dry.
Scientists long believed stem tetrapods largely disappeared after a major ecological event called the Carboniferous Rainforest Collapse. That event caused widespread destruction of tropical forests and wiped out the humid environments many early tetrapods depended on.
Creatures like Tanyka should have been gone long before it ever appeared. Yet there it was, grinding food with its twisted jaw, millions of years later than anyone expected.
One possible explanation: species in the southern part of Pangaea may have experienced different climates than those in the north. Those conditions may have allowed them to survive after northern populations went extinct.
The fossil record near the Amazon, and in excavation sites around the world, may hold more creatures waiting to be discovered that defy what we think we know.
And it all started with one twisted jawbone that nobody could explain.
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