For over a decade, between 2012 and 2023, fragments of these ancient lives were gathered from the Pedra de Fogo Formation. The creature’s name, Tanyka amnicola, honors this heritage, combining the Guaraní word for jaw with the Latin for river-dweller. It was a substantial animal, measuring roughly two metres in length, yet its mouth told a story that contradicted the known history of its kind. Unlike the vertical, needle-like teeth of its carnivorous relatives, this creature possessed large conical teeth that pointed sideways.
This peculiar anatomy led Cisneros and his international team to a startling hypothesis. In a lineage previously defined by predation, this animal appears to have been a grazer. These sideways teeth likely allowed it to scrape algae or aquatic plants from the riverbeds of the Permian period—the first evidence of such a diet in any fossil amphibian.
The discovery also rewrites the geography of the ancient world. These amphibians, known as baphtetids, were long thought to be confined to the coal swamps of the Northern Hemisphere. To find them in Brazil proves that the lineage had crossed into the southern supercontinent of Gondwana and persisted far longer than previously assumed. Furthermore, the environment where they were found was not a permanent wetland, but a warm, seasonally dry landscape.
This suggests a resilience that challenges the theory that these early tetrapods vanished because they were tethered to the water. By moving into the dry basins and perhaps turning to the greenery for sustenance, Tanyka amnicola found a way to endure. All one thousand fossils collected during the study remain under the care of the Universidade Federal do Piauí, a quiet record of a time when life first began to experiment with the possibilities of the land.