Discovery
Paleontologists have identified a prehistoric creature with a twisted jaw and sideways-facing teeth, which existed 275 million years ago. This species was considered a "living fossil" during its time.
The new species, Tanyka amnicola, is an archaic member of the tetrapod group, including modern reptiles, birds, mammals, and amphibians. The findings were published in the journal Proceedings of the Royal Society B. Researchers identified the species from nine fossilized lower jawbones, each approximately 6 inches (15 centimeters) long, found in a dry riverbed in northeastern Brazil.
Description of Tanyka Amnicola
T. amnicola existed during the Permian period, predating dinosaurs, and represented an "evolutionary relic." Many early stem tetrapod lineages had disappeared by this time, but the lineage of T. amnicola persisted as tetrapods diversified.
Jason Pardo, lead study author, described Tanyka as a "living fossil during its time, similar to a platypus," noting it remained a member of the stem tetrapod lineage even after more modern tetrapods evolved.
Based on its close relatives, T. amnicola may have resembled a salamander with a longer snout and possibly measured up to 3 feet (91 centimeters) in length. The fossil's geological context suggests the creature lived in lake environments and had aquatic habits.
Unique Features and Diet
Analysis of the lower jawbones indicated features where the creature's teeth pointed outward to the sides, a departure from the upward orientation typically observed in other tetrapods. Pardo stated that the consistent presence of this twist across nine well-preserved jawbones confirmed it as an inherent anatomical feature.
The inner surface of the lower jawbone was rotated upward and covered in denticles, small teeth-like structures that formed a grinding surface. These features suggest a unique feeding mechanism.
The authors hypothesize that T. amnicola consumed small invertebrates or potentially plant material, a dietary habit that would be notable as other stem tetrapods are generally considered carnivorous.
Paleontological Significance
During the time T. amnicola existed, Brazil was part of the supercontinent Gondwana. The discovery offers insights into the animal communities of Gondwana during this period.
Ken Angielczyk, a curator of paleomammalogy at the Field Museum and study co-author, stated that Tanyka "provides information on the structure and feeding habits within this ancient community."