Prehistoric water-dwelling weirdo with sideways teeth and a twisted jaw was already a ‘living fossil’ 275 million years ago
Paleontologists have revealed a strange prehistoric creature with a twisted jaw and sideways-facing teeth, and this water-dwelling weirdo was already a “living fossil” when it existed 275 million years ago.
The newly described species, named Tanyka amnicolais an archaic member of the tetrapods – a large group of four-membered vertebrates that today includes reptiles, birds, mammals and amphibians, according to a study published Wednesday (March 4) in the journal Proceedings of the Royal Society B.
“Tanyka comes from an ancient lineage that we didn’t know had survived until now, and it’s also a really strange animal,” said the study’s lead author. Jason Pardoassociate researcher at the Field Museum in Chicago, said in a statement. “In the sense that Tanyka was a remaining member of the stem tetrapod lineage, even after the evolution of newer, more modern tetrapods, Tanyka is a bit like a platypus. It was a living fossil in his time.”
The researchers identified the new species from nine fossilized lower jaws, each about 15 centimeters long, recovered from a dried-up river bed in northeastern Brazil. Although the creature’s lower jaws were distinctive enough for the team to determine that the fossils represented a new species, the absence of other fossilized remains means that much about the animal remains unknown.
So it’s not a deformation, it’s just the way the animal was made.
Jason Pardo, research associate at the Field Museum
However, given what is known about his close relatives, T. amnicola might have looked like a salamander with a slightly longer snout. It may have measured up to about 36 inches in length, Pardo said. The type of rocks in which the fossils were found also indicate that the creature lived in lake environments and likely had “aquatic habits,” according to the newspaper.
Analysis of the lower jaws revealed some intriguing features, including the fact that they were twisted so that the creature’s teeth pointed outwards, rather than upwards, as is the case in virtually all other tetrapods.
“The jaw has this weird twist that drove us crazy trying to figure it out,” Pardo said. “We’ve been scratching our heads for years, wondering if this is some kind of deformation. But at this point, we have nine jaws from this animal, and they all have this twist, including the ones that are really, really well preserved. So it’s not a deformation, it’s just the way the animal was made.”
In addition, the inner surface of the lower jaw, which faces the tongue in humans, has been turned upward; it was covered with a “remarkable” array of small tooth-like structures, called denticles, which would have formed a grinding surface, according to the study. These features suggest the animal had a “relatively unique way” of feeding, Pardo said.
The authors suspect that T. amnicola was adapted for munching on small invertebrates or, potentially, plant material. This would be unusual, given the lack of evidence for a plant or omnivorous diet in other stem tetrapods, which would have been carnivores, the team said.
When T. amnicola lived, Brazil was part of the supercontinent Gondwana. According to the release, the discovery opens a window into the animals of Gondwana during this period. “Tanyka tells us how this community really worked, how it was structured and who ate what”, co-author of the study Ken Angielczykcurator of paleomammology at the Field Museum, said in the release.
Pardo, J., Marsicano, C., Smith, R., Cisneros, J., Angielczyk, K., Fröbisch, J., Kammerer, C. and Richter, M. (2026). An aberrant stem tetrapod from the early Permian of Brazil. Proceedings of the Royal Society B. https://doi.org/10.1098/rspb.2025.2106
