C. Marsicano
Gaiasia jennyae, a newly discovered freshwater apex predator with a body length of up to 4.5 meters, lurked in marshes and lakes about 280 million years ago. Its broad, flattened head had powerful jaws full of large fangs, ready to seize any prey unfortunate enough to swim past.
The problem is, as far as we know, it shouldn’t have been that big, it should have gone extinct tens of millions of years before the time it apparently lived, and it shouldn’t have been found in northern Namibia. “Gaiasia it’s the first really good look we have at a completely different ecosystem that we didn’t expect to find,” says Jason Pardo, a postdoctoral fellow at the Field Museum of Natural History in Chicago. Pardo co-authored a study on Gaiasia jennyae The discovery was recently published in Nature.
Common ancestry
“Tetrapods were the animals that crawled out of the water about 380 million years ago, maybe a little earlier,” explains Pardo. These ancient creatures, also known as stem tetrapods, were the common ancestors of modern reptiles, amphibians, mammals and birds. “Those animals lived until what we call the end of the Carboniferous, about 370-300 million years ago. A few made it and lasted longer, but mostly they disappeared about 370 million ago,” he adds.
This is why the discovery of Gaiasia jennyae in the 280 million year old rocks of Namibia was so surprising. Not only was it not extinct when the rocks where it was found were laid bare, but it was dominating its ecosystem as an apex predator. By today’s standards, it was like being stranded on an isolated island waiting for animals that should have been dead for 70 million years, like a living, breathing T-rex.
“Skull of Gaiasia we found it to be about 67 centimeters long. We also have a front end of her upper body. We know she was at least 2.5 meters long, maybe 3.5, 4.5 meters – big head and a long body, like a salamander,” says Pardo. He told Ars that Gaiasia was a suction feeder: it opened its jaws underwater, which created a vacuum that sucked in its prey. But the large, interlocking fangs reveal that a powerful bite was also one of its weapons, perhaps used to hunt larger animals. “We doubt it Gaiasia they feed on bony fish, freshwater sharks and possibly other, smaller ones Gaiasia,” Pardo says, suggesting it was a fairly slow, ambush predator.
But considering where it was found, the fact that there was plenty of prey to ambush is perhaps even more shocking than the animal itself.
Location, location, location
“The continents were organized differently 270-280 million years ago,” says Pardo. At that time, a megacontinent called Pangea had already split into two supercontinents. The northern supercontinent called Laurasia included parts of modern North America, Russia, and China. The southern supercontinent, home of gaiasia, was called Gondwana, which consisted of present-day India, Africa, South America, Australia and Antarctica. And Gondwana at that time was very cold.
“Some researchers assume that the entire continent was covered in glacial ice, just as we saw in North America and Europe during the ice ages 10,000 years ago,” says Pardo. “Others claim it was more patchy – there were spots where the ice was not present,” he adds. Still, 280 million years ago, northern Namibia was about 60 degrees south latitude – roughly where the northernmost reaches of Antarctica are today.
“Historically, we thought tetrapods [of that time] lived much like modern crocodiles. They were cold-blooded, and if you’re cold-blooded the only way to get bigger and stay active would be to be in a very hot environment. We believed that such animals could not live in colder environments. Gaiasia it shows that this is absolutely not the case”, asserts Pardo. And it overturned much of what we knew about life on Earth Gaiasiatime for.