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Twisted-Jaw Fossil: Ancient 'Living Fossil' Found in Brazil
Paleontologists uncover a remarkable 275-million-year-old tetrapod with a uniquely twisted jaw and sideways-facing teeth.
Published on Mar. 4, 2026
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Paleontologists have discovered a previously unknown species of prehistoric tetrapod named Tanyka amnicola in Brazil. This ancient creature, dating back 275 million years to the Permian period, is distinguished by its bizarrely twisted jaw and sideways-facing teeth, offering a unique window into the evolution of four-limbed vertebrates.
Why it matters
The discovery of Tanyka amnicola challenges previous assumptions about the timeline of tetrapod evolution and highlights the diversity of life that existed during the Permian period. As a 'living fossil' from an older lineage that persisted even as more modern tetrapods diversified, Tanyka provides valuable insights into the evolutionary history of four-limbed vertebrates.
The details
The fossil was first discovered in a dry riverbed in northeastern Brazil, where researchers repeatedly found unusual, curved, and twisted jawbones. Initially, they suspected a deformity, but the consistent presence of this feature across nine fossilized lower jawbones confirmed it was a natural characteristic of the species. The twist in the jaw caused the teeth to point outwards, a unique trait not seen in other tetrapods. The inner surface of the lower jawbone was also rotated upwards and covered in compact, tooth-like structures called denticles, forming a grinding surface. Researchers hypothesize that Tanyka may have consumed small invertebrates or even plant material, a potentially unusual diet for stem tetrapods.
- The Tanyka amnicola fossil dates back approximately 275 million years, to the Permian period.
The players
Tanyka amnicola
A previously unknown species of prehistoric tetrapod discovered in Brazil, distinguished by its bizarrely twisted jaw and sideways-facing teeth.
Jason Pardo
A research associate at the Field Museum in Chicago and the lead author of the study on Tanyka amnicola.
Ken Angielczyk
A curator at the Field Museum and a co-author of the study on Tanyka amnicola.
What they’re saying
“Tanyka helps researchers understand how the ancient ecosystem functioned and how different species interacted.”
— Ken Angielczyk, Curator, Field Museum
What’s next
Future excavations in the same region of Brazil may yield additional Tanyka amnicola fossils, providing a more comprehensive picture of this ancient creature and its place in the Permian ecosystem. Researchers are also exploring the possibility that similar species may have existed in other parts of Gondwana, potentially rewriting our understanding of early tetrapod distribution.
The takeaway
The discovery of Tanyka amnicola, a 'living fossil' from the Permian period, challenges previous assumptions about the timeline of tetrapod evolution and highlights the diversity of life that existed during this ancient era. This unique fossil provides a crucial glimpse into the animals that inhabited the Gondwana supercontinent, offering valuable insights into the evolutionary history and ecosystem dynamics of early four-limbed vertebrates.
