Deep in a Brazilian riverbed, paleontologists stumbled onto something that made them scratch their heads for years. Nine fossilized jawbones, each about six inches long, belonged to an animal that shouldn’t have existed when it did. The creature, formally named Tanyka amnicola, lived around 275 million years ago during the early Permian Period, and it was, in a very real sense, a relic of an older world. A study published in Proceedings of the Royal Society B describes this discovery, revealing an animal so unusual that researchers initially wondered if something had gone wrong during fossilization.
But here’s the thing: nothing went wrong. All nine jaws showed the same bizarre twisted structure, complete with teeth pointing sideways and rows of tiny grinding teeth on the inner surface. This wasn’t a deformation. This was just how Tanyka was built.
A Survivor From a Dead Lineage
Jason Pardo, the study’s lead author who worked on the project during his post-doctoral fellowship at the Field Museum in Chicago, explained the confusion. “The jaw has this weird twist that drove us crazy trying to figure it out,” he says. “We were scratching our heads over this for years, wondering if it was some kind of deformation. But at this point, we’ve got nine jaws from this animal, and they all have this twist, including the really, really well-preserved ones. So it’s not a deformation, it’s just the way the animal was made.”
Tanyka belonged to a group called stem tetrapods, the ancient ancestors of all modern four-limbed animals. Early on, tetrapods split into two major branches: one that evolved to lay eggs on land (which became reptiles, birds, and mammals), and another that kept laying eggs in water (which became modern amphibians). Here’s where it gets interesting: after this split happened, some stem tetrapods just… kept existing. They didn’t evolve into anything new. They just hung around as living fossils.
Think of it like this. Modern mammals mostly give live birth, but the platypus still lays eggs, retaining a trait from its ancient ancestors. “In the sense that Tanyka was a remaining member of the stem tetrapod lineage, even after newer, more modern tetrapods evolved, Tanyka is a little like a platypus. It was a living fossil in its time,” Pardo explains.
A Grinding Jaw Built for Plants
The most telling feature of Tanyka isn’t what we found, but what we didn’t find. Researchers recovered only jawbones, not complete skeletons. That limitation matters. Ken Angielczyk, a curator of paleomammalogy at the Field Museum and Pardo’s advisor, notes that without finding a jaw attached to a skull or other definitively associated bones, scientists can’t be entirely certain about the rest of the animal’s anatomy. “Until we find one of those jaws attached to a skull or other bones that are definitively associated with the jaw, we can’t say for sure that the other bones we find near it belong to Tanyka,” he says.
Still, based on comparisons with related species, researchers suspect Tanyka resembled a salamander with a slightly longer snout, possibly reaching up to three feet in length. The surrounding rock suggests it lived in freshwater lakes and rivers.
What the jaw does tell us is fascinating. Human teeth point upward toward the roof of the mouth, right? Tanyka’s lower jaw was twisted so its teeth pointed sideways instead. The inner surface of the jaw, which faces the tongue in humans, faced upward in Tanyka. This surface was covered with tiny teeth called denticles that worked like a cheese grater, grinding against similar teeth on the upper jaw. “The teeth would have been rasping against each other, in a way that’s going to create a relatively unique way of feeding,” Pardo says.
This grinding mechanism screams herbivore. Most stem tetrapods are thought to have been carnivorous, which makes Tanyka unusual. Juan Carlos Cisneros, an author of the paper at the Federal University of Piauí in Brazil, confirms the implication: “Based on its teeth, we think that Tanyka was a herbivore, and that it ate plants at least some of the time.”
A Window Into an Ancient World
The discovery matters beyond just adding another weird creature to the science record. Around 275 million years ago, Brazil was part of Gondwana, a vast supercontinent that included South America, Africa, Australia, and Antarctica. Fossils from this era and place are rare compared to finds from the Global North, making every discovery valuable.
“The Pedra de Fogo Formation in Brazil is one of the only windows we have into Gondwana’s animals during the early Permian Period of Earth history, and Tanyka is telling us about how this community actually worked, how it was structured, and who was eating what,” Angielczyk says.
This single species, known only from nine twisted jawbones, fills a gap in our understanding. It shows that ancient ecosystems included plant-eaters with bizarre feeding mechanisms, that lineages could persist for millions of years without evolving, and that life finds strange solutions to everyday problems like grinding up vegetation.
The real question now is what the rest of Tanyka looked like. A complete skeleton might revolutionize our understanding of this creature. Until then, we’re left with a twisted jaw and a lot of informed guesses about one of history’s strangest survivors.
