Scientists have identified a new species of ancient animal, Tanyka amnicola, from fossils unearthed in a dry riverbed in Brazil. Dating back 275 million years, this stem tetrapod featured a highly unusual twisted jaw suggesting it ground plant material. The discovery sheds light on early Permian life in Gondwana.
In a dry riverbed within a forest near the Amazon in Brazil, paleontologists uncovered nine fossilized jawbones, each about six inches long, from an animal that lived around 275 million years ago. The team found no additional bones linked to a full skeleton. These jaws, described in a study published in Proceedings of the Royal Society B, belong to Tanyka amnicola—a name derived from the Indigenous Guaraní word for 'jaw' and Latin for 'living by the river.'The species represents a 'living fossil' from an ancient stem tetrapod lineage that persisted alongside more modern tetrapods, akin to the platypus among mammals. Lead author Jason Pardo, a research associate at the Field Museum, noted, 'Tanyka is from an ancient lineage that we didn't know survived to this time, and it's also just a really strange animal. The jaw has this weird twist that drove us crazy trying to figure it out.' He confirmed the twist was natural, as all nine specimens shared it, including well-preserved ones.The jaw's structure is distinctive: teeth pointed outward and sideways, with inner surfaces lined by small denticles forming a grinding area like a cheese grater. Researchers infer Tanyka was likely a herbivore, processing plants by rasping teeth together—a rarity among typically carnivorous stem tetrapods. 'Based on its teeth, we think that Tanyka was a herbivore, and that it ate plants at least some of the time,' said co-author Juan Carlos Cisneros of the Federal University of Piauí.From the Pedra de Fogo Formation, the fossils offer insights into early Permian ecosystems in Gondwana. Co-author Ken Angielczyk, a Field Museum curator, explained, 'Tanyka is telling us about how this community actually worked, how it was structured, and who was eating what.' The animal may have resembled a salamander up to three feet long, inhabiting freshwater environments.