A groundbreaking discovery in paleontology has unveiled a new genus and species of Permian archaic tetrapods, identified from fossilized jawbones found in Brazil. Named Tanika amnicola, this intriguing amphibian relative showcases unique horizontal teeth and abrasive, file-like surfaces. This suggests that ancient tetrapod vertebrates may have begun experimenting with plant consumption much earlier than previously thought.

Tanika amnicola thrived in the southern regions of the Gondwana supercontinent during the early Permian period, approximately 275 million years ago.

“Tanika amnicola has captivated researchers,” says Dr. Jason Pardo, a paleontologist at the Field Museum.

“We were intrigued by an unusual twist in its jaw that we were determined to understand.”

“For years, we speculated whether this was a variant, but with nine jaw samples now extracted, all exhibiting this distinctive twist—some exceptionally well preserved—it’s clear this was characteristic of the species, not a deformity,” he added.

Tanika amnicola represents a pedunculated tetrapod lineage, the oldest subset of tetrapods that eventually diversified into two major groups: those laying eggs outside of aquatic environments and those that lay eggs in water.

Modern reptiles, birds, and mammals descend from the branches that evolved to lay watertight eggs on land, while contemporary amphibians, like frogs and salamanders, represent tetrapod relatives that require moist environments for their eggs.

Nonetheless, some pedunculated tetrapods persisted even after more modern variations evolved, with Tanika amnicola being a notable example.

“In essence, Tanika amnicola survived as a remnant of the pedunculated tetrapod lineage long after newer tetrapods emerged. Its appearance is somewhat akin to that of a platypus—a true living fossil,” remarked Dr. Pardo.

Many aspects of Tanika amnicola‘s anatomy still puzzle scientists.

“The isolated jawbones we’ve discovered are remarkably unique and distinctive,” stated Dr. Ken Angielczyk, curator of paleomammalogy at the Field Museum.

“However, until we find a skull or additional bones definitively connected to these jaw samples, we cannot conclusively ascribe other nearby bone fragments to Tanika amnicola.”

Yet, the jawbone alone is revealing, demonstrating the rarity of this creature.

“Run your tongue across your lower teeth. Do you feel the tops pointing towards the roof of your mouth?” they explained.

“In Tanika amnicola, the lower jaw twists, with teeth projected sideways rather than upwards.”

“Conversely, the portion of the jaw facing the tongue in Tanika amnicola angles upward, towards the roof of the mouth.”

“The jawbone is adorned with numerous small teeth, known as denticles, creating a grinding surface akin to a cheese grater.”

Scientists hypothesize that the teeth and dental arrangements in the upper jaw harmonized with those in the lower jaw.

“We theorize that the lower jaw’s teeth would rub against similar teeth in the upper mouth,” Pardo explained.

“This grinding action suggests a distinctive feeding method predominantly aimed at plant material.”

“Based on dental morphology, we believe Tanika amnicola was likely an herbivore, consuming plants at least occasionally,” remarked Dr. Juan Carlos Cisneros from the Federal University of Piauí.

“It’s astonishing that a quadrupedal creature like Tanika amnicola existed, especially considering most of its tetrapod relatives primarily consumed meat, indicating an evolved adaptation to a plant-based diet.”

The peer-reviewed findings are published in the journal Proceedings of the Royal Society B.

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Jason D. Pardo et al.. 2026. A quadrupedal organism with an anomalous jaw structure living during the early Permian period in Brazil. Proc Biol Sci 293 (2066): 20252106; doi: 10.1098/rspb.2025.2106