You could call it a “swamp thing.” About 280 million years ago, a giant creature that resembled a salamander but had fearsome pointed teeth roamed the swamps and lakes of what is now Namibia, ambushing prey as an apex predator in a cold ecosystem long before the dinosaurs.
The creature, called Gaeasia jennae, lived in the Permian period and was at least 8 feet (2.5 meters) long and possibly up to 13 feet (4 meters), according to the researchers who announced the discovery of its fossil remains. Its large, round, flat skull was more than 2 feet (60 cm) long, and it had a pair of pointed teeth that connected to each other at the front of its mouth.
“Broad and flat heads in modern animals are typically used to generate strong suction force to attack prey suddenly. Gaeasia had huge pointed teeth to capture and kill large prey,” said Jason Pardo, a postdoctoral fellow in paleontology at the Field Museum in Chicago and one of the leaders of the research published this week in the journal Nature.
The fossils were discovered in Namibia, a country in southwest Africa. Due to the gradual movement over time of the crustal plates that make up the Earth’s outer layer – called plate tectonics – this location was even further south when Gaeasia lived, roughly equivalent to the current northernmost point of Antarctica. The water body it lived in may have been located along with patches of ice and glaciers.
“In the far south, where Gaeasia lived, the Ice Age was ending, and it was still cold enough that there were large glaciers, even at low elevations,” Pardo said.
About 100 million years before Gaeasia came into existence, the first terrestrial vertebrates evolved from fleshy-finned fishes. These are called stem tetrapods. They lived amphibious lifestyles, although they were not true amphibians. The term tetrapod, meaning “four legs”, refers to all terrestrial vertebrates. At first, stem tetrapods gave rise to evolutionary lineages that produced true amphibians, reptiles, and mammals.
While all this was happening, some stem tetrapods survived, especially in remote areas such as Namibia at the time. Gaeasia was one of these.
“Most of what we know about terrestrial life at this time comes from the ancient equatorial zone, preserved in rocks from Europe and North America. Based on this, we thought that early tetrapods were trapped in the tropics because of their physiology,” said Pardo, until they disappeared amid competition from newly evolved competitors.
“Gaecia clearly shows that this is not true. Stem tetrapods were thriving at high latitudes in very cold environments, and those ecosystems were dominated by some very unexpectedly primitive animals. It forces us to rethink a lot about early tetrapod evolution,” Pardo said.
Gaeatia was thus a stubborn remnant.
“Gaecia is very different from other organisms we’ve seen, so it could be a stand-alone creature, but it could also be part of a vibrant ecosystem of similar animals that are no longer an important part of the ecosystem of the tropics,” Pardo said.
Evolution was proceeding at a rapid pace during the Permian period.
“At this time we’re seeing a flurry of evolution in the ancestors of mammals, such as Dimetrodon, an animal the size of a mountain lion, which resembled a large lizard with a huge sail on its back and was the top predator in most of these ecosystems. We’re also seeing the ancestors of reptiles diversify in interesting ways that mirror modern lizards and the first true amphibians,” Pardo said.
The Permian Period ended with Earth’s worst mass extinction, about 252 million years ago. The first dinosaurs appeared during the Triassic Period, about 230 million years ago.
The creature’s name Guyasia refers to the Guy-As rock formation in Namibia, where it was found, and Jennya honors the late British paleontologist Jenny Clack, who studied early tetrapods. But how about a catchy nickname for it?
“‘Swamp Thing’ is great,” Pardo said.
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