Startling find: a prehistoric water-dwelling oddball with a twisted jaw and sideways teeth was already a true “living fossil” 275 million years ago.
Paleontologists have introduced a bizarre ancient creature, notable for its twisted jaw and teeth that faced outward to the sides. This aquatic oddity was already considered a living fossil during its time, about 275 million years in the past.
The newly described species, named Tanyka amnicola, belongs to an early lineage of tetrapods — the broad group that today encompasses reptiles, birds, mammals, and amphibians — according to a study published on March 4 in the journal Proceedings of the Royal Society B.
"Tanyka comes from an ancient lineage we didn’t know persisted this long, and it’s also a remarkably strange animal," says lead author Jason Pardo, a research associate at the Field Museum in Chicago. "As a surviving member of the stem tetrapod lineage even after newer, more modern tetrapods evolved, Tanyka is somewhat akin to a platypus. It was a living fossil in its era."
The team identified the new species from nine fossilized lower jawbones, each about 6 inches (15 centimeters) long, recovered from a dry riverbed in northeastern Brazil. Although the jawbones were distinctive enough to define a new species, the absence of additional fossils leaves many questions about the animal’s full appearance and lifestyle.
So, this is not a deformity; it’s just the creature’s natural construction.
Based on what’s known about close relatives, T. amnicola may have looked like a salamander with a slightly longer snout and could have reached roughly 3 feet (about 91 centimeters) in length, according to Pardo. The rock types where the fossils were found suggest the animal inhabited lake environments and likely led an aquatic lifestyle.
The jaw analysis revealed intriguing features — most notably, the jaw was twisted so the teeth pointed outward to the sides rather than upward, as seen in nearly all other tetrapods.
"The jaw twist was maddening at first," Pardo explained. "We spent years wondering if it was a deformation. But with nine jaws, including highly preserved specimens, the twist is consistently present, indicating it’s a natural feature of the animal."
In addition, the inner surface of the lower jaw — the tongue-facing side in humans — appears rotated upward and bears a remarkable array of small, tooth-like denticles forming a grinding surface. This combination hints at a unique feeding strategy, the researchers note.
The authors propose that T. amnicola fed on small invertebrates, and perhaps even some plant material. This would be unusual for close stem-tetrapod relatives, who are generally thought to have been carnivorous, adding a provocative twist to our understanding of early tetrapod diets.
Geologically, Tanyka lived when Brazil was part of the supercontinent Gondwana. The discovery sheds light on Gondwana’s animal communities during this period and helps scientists understand how these ecosystems were structured and who ate whom.
"Tanyka teaches us about the organization of this community, its interactions, and the feeding dynamics at play," says Ken Angielczyk, co-author and paleomammalogy curator at the Field Museum.
Article sources and credits are included in the study by Pardo and colleagues, published in 2026 in Proceedings of the Royal Society B. Aristos is a freelance science journalist known for coverage of archaeology and paleontology, among other topics.
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