C. Marsicano
Gaiasia jennyae, a newly discovered freshwater apex predator with a body length of up to 4.5 meters, lurked in swamps and lakes about 280 million years ago. Its broad, flattened head had powerful jaws full of huge fangs, ready to catch any prey that was unfortunate enough to pass by.
The problem is, to the best of our knowledge, it shouldn’t have been that big, it should have gone extinct tens of millions of years before it apparently lived, and it shouldn’t have been found in northern Namibia. “Gaiasia is 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 is a co-author of a study by Gaiasia jennyae a discovery recently published in Nature.
Common ancestry
“Tetrapods were animals that came out of the water about 380 million years ago, maybe a little earlier,” explains Pardo. Also known as stem tetrapods, these ancient creatures were the common ancestors of modern reptiles, amphibians, mammals and birds. “These animals lived until what we call the end of the Carboniferous, about 370-300 million years ago. A few of them made it through and lasted longer, but most became extinct about 370 million ago,” he adds.
This is why the discovery Gaiasia jennyae in the 280 million year old rocks of Namibia was so surprising. Not only did it not become extinct when the rocks it was found in were laid down, it dominated its ecosystem as an apex predator. By today’s standards, it was like stumbling upon a remote island hosting animals that should have been dead for 70 million years, like a living breathing T-rex.
“Skull from gaiasia which we found is about 67 centimeters long. We also have the front of her upper body. We know it was at least 2.5 meters long, probably 3.5, 4.5 meters – a big head and a long, salamander body,” says Pardo. He told Ars gaiasia she was a suction feeder: she opened her jaws underwater, which created a vacuum that sucked her prey right in. But the large, interlocking fangs reveal that a strong bite was also one of her weapons, probably used to hunt larger animals. “We suspect gaiasia they feed on bony fish, freshwater sharks and possibly other smaller ones gaiasiaPardo says, suggesting it was a relatively slow, ambush-based predator.
But considering where it was found, the fact that it had enough prey to ambush is perhaps even more of a shock than the animal itself.
Location, location, location
“270-280 million years ago, the continents were organized differently,” says Pardo. At that time, one megacontinent called Pangea had already split into two supercontinents. The northern supercontinent called Laurasia included parts of modern North America, Russia, and China. Southern supercontinent, home gaiasia, was called Gondwana, which consisted of present-day India, Africa, South America, Australia, and Antarctica. And Gondwana was pretty cold back then.
“Some scientists hypothesize that the entire continent was covered in glacial ice, similar to what we saw in North America and Europe during the ice ages 10,000 years ago,” says Pardo. “Others say it was more patchy – there were these patches where there was no ice,” he adds. As recently as 280 million years ago, northern Namibia was around 60 degrees south latitude – roughly where the northernmost reaches of Antarctica are today.
“Historically, we thought of tetrapods. [of that time] they 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 a colder environment. Gaiasia shows that this is absolutely not the case,” says Pardo. And it turned a lot of what we knew about life on Earth upside down gaiasiait’s time.