An international team of palaeontologists has described a new species of early land vertebrate from Brazil. The species is named Tanyka amnicola. Researchers identified this unusual animal from fossils discovered in north-eastern Brazil. Their findings appear as an open access paper in the journal Proceedings of the Royal Society B. Importantly, the fossils reveal an amphibian with a very unusual jaw. The unique jaw morphology suggests adaptations to either specialised processing of small invertebrates or consumption of plants. This demonstrates that some stem tetrapods were exploring niches in ecosystems in the Southern Hemisphere during the Permian.
Fossils from the Pedra de Fogo Formation
The fossils come from the Pedra de Fogo Formation. This formation lies within the Parnaíba Basin of Brazil. Scientists recovered nine isolated lower jaws, each about fifteen centimetres long. Although researchers have not yet found other bones, these jaws reveal important clues. Professor Jörg Fröbisch from the Museum für Naturkunde Berlin played a key role in this study.
Professor Fröbisch commented that the discovery followed many years of work in the region. In fact, the first jaw was discovered during one of the earliest expeditions. For more than fifteen years, researchers have studied the fossils of the Parnaíba Basin. The project involves scientists from Brazil, Argentina, South Africa, the USA, the UK (London Natural History Museum) and Germany.
Life reconstruction of Tanyka amnicola grazing on some plants. Picture credit: Vitor Silva.
Picture credit: Vitor Silva
Tanyka amnicola An Ancient “Living Fossil”
Interestingly, Tanyka amnicola belonged to a very old lineage. As a result, the animal could already be considered a “living fossil” in its own time.
Professor Fröbisch explained:
“What is particularly exciting is that even during its lifetime around 275 million years ago, it could have been described as a living fossil, as it belongs to an archaic group that actually lived 30-50 million years earlier.”
During this period in Earth’s history Brazil was part of a supercontinent called Gondwana. This enormous landmass included South America, Africa, Antarctica and Australia.
A Remarkably Twisted Jaw
The lower jaw of Tanyka amnicola shows a very unusual structure. Lead author Jason Pardo explained that the twisted jaw initially puzzled the researchers. However, every fossil jaw shows the same shape. Therefore, the feature represents normal anatomy rather than damage or taphonomy.
The teeth point sideways rather than straight upwards. Meanwhile, the inner surface of the jaw tilts towards the palate. Furthermore, the jaw surface carries many small teeth. These teeth may have formed a rough grinding surface. When the mouth closed, the teeth probably rubbed against each other. Consequently, the animal could crush or shred food. Hence, the theory that this tetrapod may have been herbivorous, or at least plants made up a proportion of its diet.
Professor Juan Cisneros from the Federal University of Piauí, a co-author of the study believes the animal ate plants at least part of the time.
He stated:
“Based on the structure of its teeth, we assume that Tanyka ate plants at least some of the time. This is surprising, as most of its relatives were carnivores.”
Therefore, Tanyka amnicola may represent an early experiment in herbivory among early tetrapods.
A Window into Early Permian Ecosystems
Fossils from the early Permian are relatively rare. Consequently, every discovery provides valuable information. The Pedra de Fogo Formation offers one of the few windows into Gondwana’s ecosystems at that time.
Co-author Dr Kenneth Angielczyk commented:
“The Pedra de Fogo Formation offers one of the few windows into the animal world of Gondwana during the early Permian period. Tanyka shows us which animals lived there and what ecological roles they played.”
Fossils from this Formation also help scientists understand how early tetrapods interacted.
Tanyka amnicola probably lived close to rivers and lakes. The species name reflects its habitat, the word “amnicola” translates as “river dweller”. The genus name is derived from the local Guaraní language, it translates as “jaw”.
Researchers estimate that Tanyka amnicola may have reached around one metre in length.
More Discoveries May Follow
At present, scientists only know the animal from jawbones. However, future discoveries could change that. For example, researchers hope to find skulls or articulated skeletons. Such fossils would help reconstruct the entire animal.
Nevertheless, even these isolated jaws provide remarkable insight.
For now, Tanyka amnicola offers a fascinating glimpse into early tetrapod evolution. Moreover, it highlights the importance of the Pedra de Fogo Formation in revealing an ancient ecosystem from Gondwana.
Everything Dinosaur acknowledges the assistance of the Museum für Naturkunde Berlin in the compilation of this article.
The scientific paper: “An aberrant stem tetrapod from the early Permian of Brazil” by Jason D. Pardo, Claudia A. Marsicano, Roger Smith, Juan Carlos Cisneros, Kenneth D. Angielczyk, Jörg Fröbisch, Christian F. Kammerer and Martha Richter published in the Royal Society Proceedings B.
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