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Quick Take
The fossil of Tanyka amnicola was discovered at the edge of the Amazon rainforest in Brazil.
It has an unusual twisted jaw with denticles that it probably used to grind tough food.
It is a ‘living fossil’ because it lived alongside more modern tetrapods.
Tanyka amnicola survived the Carboniferous Rainforest Collapse despite the drastic change in climate.
An ancient species has had experts scratching their heads about its unusual jaw shape. The salamander-like creature had a highly unusual way of chewing its food. But this discovery was significant in other ways. Not only was it a ‘living fossil’, meaning that it was alive when most of its counterparts were extinct, but it also teaches us about the animals that survived the widespread extinction associated with the Carboniferous Rainforest Collapse.
Fossil With a Twisted Jaw
Scientists have recently published details about a new tetrapod fossil. Discovered at the edge of the Amazon rainforest in Brazil, the animal has been named Tanyka amnicola, which roughly means ‘jaw living next to the river’. It was its jawbone that triggered most interest, and there were initially doubts as to whether this was simply a deformation in one individual. But when experts examined nine jaws, all with the same shape, it was clear that this was how the species had looked.
Tetrapods (which include all extant and extinct amphibians and amniotes) usually have teeth facing each other. They use them to slice and grind food before swallowing. Tanyka, however, has a lower jaw that twists outward from back to front. This means that some of its teeth point out to the sides! On the inside of the jaw bones, there are tiny tooth-like projections called denticles, and these were likely used for grinding food. Scientists have not yet found any Tanyka upper jaws, but they suspect that the teeth and denticles would be arranged in the same way. Then, the upper and lower denticles would rub up against each other and grind tough food such as fibrous plant material and invertebrate exoskeletons. This also gives a clue about the animal’s diet.
How Was the Tetrapod Identified?
Tanyka amnicola is so unusual that experts initially thought it was a fish! However, when they compared it to many other species across hundreds of millions of years, they concluded that it was actually a primitive tetrapod.
Tanyka amnicola looked like a salamander but with a twisted jaw.
So, what did it look like? It probably resembled a salamander but with a longer snout. There were other bones found near the fossil, but scientists are not certain that they are from the same animal.
Why Is Tanyka Amnicola a Living Fossil?
Tanyka amnicola is a type of archaic stem tetrapod, typically referred to as ‘baphetids’. It lived 275 million years ago, but most other stem tetrapods had died out by then. They had been replaced by the ancestors of our modern amphibians, reptiles, birds, and mammals. So, it was living alongside the more modern tetrapods, which is unusual.
Animals that do this, such as the platypus, are often referred to as living fossils because they are almost living out of their time.
The Carboniferous Rainforest Collapse
305 million years ago, the Earth was warm and humid with waterlogged swamps and rainforests. Almost all of the world’s landmasses were united into one enormous supercontinent known as Pangaea. This was the late Carboniferous era, and giant insects and amphibians roamed the planet. Then, everything drastically changed.
An event called the Carboniferous Rainforest Collapse took place during the Late Moscovian to early Pennsylvanian period. The climate changed and became cooler and drier, so the plants and animals in the warm, moist rainforests struggled. The oxygen levels dropped, making it even harder for animals to survive. At the same time, there was likely intense glaciation, which would have led to lower sea levels.
The Carboniferous era was warm and wet.
©PhotoChur/Shutterstock.com
(PhotoChur/Shutterstock.com)
The early tetrapods were significantly affected by the resulting minor extinction event. They suffered from endemism, which is where different population groups become isolated from each other. The diversity of amphibian species, in particular, suffered greatly. Dry climates do not generally suit amphibians!
What Tanyka Tells Us About Tetrapod Survival
It was once assumed that most stem tetrapods died out during the Carboniferous Rainforest Collapse. However, the discovery of Tanyka shows that this was not the case.
Scientists do not yet know how they managed to survive against the odds with a backdrop of such significant environmental change. However, one theory is that they may have been more able to withstand colder temperatures. Also, they may have evolved a tolerance of drier conditions. Possibly, the areas where they lived, in the southern part of Pangea, may have been warmer than the rest of the supercontinent. Their unusual jaw shape also shows that this lineage was still evolving to exploit other food sources. It crushed them with its unusual jaws.
Ultimately, this shows that the stem tetrapods were not simply wiped out by the Carboniferous Rainforest Collapse and replaced by the pan-amphibians and amniotes. Instead, this was a complex and protracted process. It also shows that the ancient supercontinent of Gondwana (one half of Pangea) had a diverse animal population until the end of the early Permian. Tanyka did not simply survive the Carboniferous Rainforest Collapse; they thrived after it!
The post Scientists Found a “Living Fossil” with a Twisted Jaw—and Teeth That Point Sideways appeared first on A-Z Animals.