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A huge, fanged creature with a head shaped like a toilet seat lurked in swamps near the edge of the world 280 million years ago, long before the appearance of the first dinosaurs, new research has found.
Now, the scientists who made the surprising discovery of its fossils in Namibia and Brazil want to know why the ancient salamander predator seemed to thrive millions of years after its relatives near the equator expired.
They reported the results of their study, the result of work that began in 2018, on Wednesday in the journal Nature.
“Gaiasia jennyae was much larger than a person, and it was probably hanging out near the bottom of lakes and ponds,” said study co-author Jason Pardo, a National Science Foundation postdoctoral fellow at the Museum of Natural History Field in Chicago, in a statement. “It has a large, flat, toilet seat-shaped head, which allows it to open its mouth and suck its prey. It has these huge fangs, the whole face of the mouth is just huge teeth. It’s a big predator, but it can be quite a slow ambush predator.”
So far, paleontologists have found a well-preserved skull and spine, several partial skulls, vertebrae and pieces of jaw after two seasons of fieldwork. The largest skull is more than 2 feet (0.6 meters) long.
“When we found this huge specimen just lying on the outcrop as a giant concrete, it was a shock,” said study co-author Claudia Marsicano, a researcher and professor in the Department of Geology in University of Buenos Aires, in a. statement. “I knew from the moment I saw it that it was something completely different.”
Ancient Polar creatures
Together, the fossil pieces tell the story of a creature that defied all expectations based on the evolutionary paths of the more famous animals from the time, which lived mostly closer to the equator.
Creatures living farther south were harder to pin down, and less is known about the animals that lived closer to the poles.
Gaiasia lived in the middle of the Permian period, which lasted between 298.9 million years and 251.9 million years ago. It thrived as a top predator 40 million years before dinosaurs evolved to roam the Earth, according to the study.
At the time, the planet was dominated by an empire called Pangaea, which included a large landmass called Gondwana. The land that is now South America included Africa, Antarctica, Australia, New Zealand and the Indian subcontinent.
Currently, Namibia is north of South Africa. But 300 million years ago, where Namibia is now, it was much further south and located near the northernmost point of today’s Antarctica.
As the Permian period began, the planet was warming after the end of the ice age. While wetlands near the equator dried up and became forests, cold swamps remained closer to the poles and were framed by glaciers and ice.
New animals appeared in the warmer and drier regions near the equator as four-legged vertebrates called tetrapods evolved and split into groups that became the basis of modern animals. But that doesn’t seem to be the case at the poles, where ancient creatures were doing their own thing, Pardo said.
“Gaiasia is a stem tetrapod — it’s a holdover from that earlier group, before they evolved and split into groups that would make mammals and birds and reptiles and amphibians, called crown tetrapods,” Pardo said. “It’s surprising that Gaias is so archaic. It belonged to organisms that probably went extinct 40 million years earlier.”
An unrivaled predator
Part of the reason Gaiasia surprises researchers so much is that it was so large and dominant.
“There are some other ancient animals still hanging around from 300 million years ago, but they were rare, they were small, and they were doing their own thing,” Pardo said. “Gaiasia is big, and it’s abundant, and it seems to be the top predator in its ecosystem.”
While the creature’s contemporaries would have been about the size of modern eels or snakes, Gaiasia probably reached about 10 feet (3 meters) in length. But it could be twice that long, Pardo said.
Fossils of Ghaiasia’s limbs, if any, or its tail, have yet to be found, but researchers know where the creature fits in the tree of life, and Ghaiasia’s distant ancestors and relatives had limbs. . Finding more fossils during future fieldwork could help researchers improve estimates of body size, Pardo said.
What they have found so far is a portrait of a terrifying creature you don’t want to encounter, he said.
Gaiasia’s broad, flat skull was like two giant plates stacked on top of each other. As the creature opened its mouth, a natural suction would occur, drawing in fish, sharks or any other nearby prey. Inside, fangs 3 inches (7.6 centimeters) long were waiting to break prey so Gaiasia could swallow its meals whole, Pardo said.
“After examining the skull, the facial structure of the skull caught my attention,” Marsicano said. “It was the only part that was clearly visible at the time, and it showed that large claws were very unusually joined together, creating a unique grip for early tetrapods.”
The research team suspects that Gaiasia went extinct around 268 million years ago, but it is not clear what caused the tetrapod to disappear.
A mystery in the far south
The discovery of Gaia forces scientists to ask new questions, such as how it survived for so long in such a cold environment. Normally, such an animal would adapt to be an endothermic, a warm-blooded animal that can regulate its body temperature by producing its own heat.
But Gaiasia was an ectotherm, relying on its external environment to regulate its body temperature.
“It’s a large aquatic animal, basically something between a fish and an amphibian, and it’s reaching very large body sizes,” Pardo said. “If you’re cold-blooded, that’s very difficult because you have to eat a lot of food and live for a long time to grow.”
Gaiasia may have lived between 20 and 40 years old to reach such huge sizes, but researchers can’t be sure, Pardo said.
As well as looking for more fossil examples of the species, the researchers are also curious to find other animals that lived in this far south ecosystem.
“We are told that what was happening in the far south was very different from what was happening at the equator. And that’s very important because there were many groups of animals seen at this time that we don’t really know where they came from,” said Pardo.
“The fact that we found Gaiasia so far south tells us that there was a thriving ecosystem that could support these very large predators,” he said. “The more we look, we may find more answers about these large groups of animals we care about, like the ancestors of modern mammals and reptiles.”
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