Giant swamp creature found in Namibia was an ambush predator 

After three years of meticulous research, an international team of researchers has discovered a fossilized giant basal tetrapod in Namibia’s arid region. 

Basal tetrapods are early four-legged vertebrates that lived during the crucial transition from water to land. 

This three-meter-long skeleton, found in the Ugab River valley, is the largest ever discovered and challenges the belief that such early vertebrates lived only in the northern hemisphere. 

Early evolution of terrestrial animals 

The discovery provides crucial insights into the early evolution of terrestrial animals, highlighting the importance of southern continents in future research.

Supported by PAST Africa and the National Geographic Society, the team of paleontologists from South Africa, Namibia, Argentina, and the US sought evidence of the earliest land-dwelling vertebrates in Gondwana. 

Existing from about 550 to 180 million years ago, Gondwana included parts of modern South America, Africa, Antarctica, Australia, and India.

Nearly complete tetrapod skeleton

While conducting fieldwork in Namibia, the team surveyed the rugged terrain when they made a significant find. 

Study co-author Roger Smith is a distinguished professor at the Evolutionary Studies Institute at Wits University and emeritus research associate at Iziko Museums, Cape Town.

“The nearly complete skeleton was preserved in mudstone from an ancient freshwater lake. As the soft tissue decomposed, gasses formed that caused calcium carbonate to crystallize around the bones, creating a hard crust that protected them from being crushed as they were buried deeper,” explained Smith.

Incredible skeleton discovery 

Mr. Sibusiso Mtungata, a skilled fossil technician from the Iziko Museum, recounts the moment of discovery. 

“We had found isolated vertebrae of something big, so we were looking for a more complete skeleton,” said Mtungata.

“I came across two round cylinders of rock with bone in the middle which fitted together – and then a third. I called Roger over to help me find more, and as we walked upslope, he spotted a large flat rock which he recognized as the head.” 

“When we looked along the edge and saw rows of teeth, we knew we had finally found what we had been searching for – a nearly complete skull and skeleton!”

Skull with large interlocking fangs 

“As soon as I saw this enormous animal, I knew it was a different species,” said lead author Claudia Marsicano, a paleontologist at the University of Buenos Aires, Argentina. 

“There is no record of giant basal tetrapods during the Carboniferous-Permian transition (approximately 299 million years ago) anywhere in the world, and certainly none from the southern continents that made up Gondwana.”

“What caught my attention next was the structure of the front part of the skull, which was sticking out of the ground. It showed unusually large interlocking fangs.” 

According to the experts, it was an ambush predator which ate the fish that lived in the same lake.

Collecting the tetrapod fossil

Collecting the fossil was a difficult process. “The skeleton had already weathered out of the rock, so there was no need for excavation, but the whole team spent hours searching for fragments that had fallen off the skull block and moved downslope,” noted Mtungata. 

The skeleton was then transported to the Iziko South African Museum in Cape Town for meticulous preparation in the Karoo Fossil Laboratory, a process that spanned two years. 

“Mechanical preparation was a challenge because it was too large to CT scan, so I didn’t know what to expect – especially in the palate where teeth of all different sizes were everywhere. And there was up to 10 cm of rock around the vertebrae that needed to be drilled away, creating so much red dust that we had to bring in a special extractor,” said Mtungata.

Distinctive skull structure 

The fossil preparation revealed that the large, flattened skull was adorned with unique patterns and had a distinctive palate structure, with enormous, backward-curved fangs in both the upper and lower jaws. 

Initially thought to be a large amphibian, further examination revealed that the skull had features of much older, less evolved four-legged animals, which were previously found only in older rocks in the northern hemisphere.

The early history of tetrapods 

“We named the new species Gaiasia jennyae. ‘Gaiasia’ is after Gaias, a nearby desert spring where the fossil was found. ‘Jennyae’ honors Professor Jennifer Clack, a world-renowned expert in early tetrapod evolution, who passed away in 2020,” said Smith.

The findings indicate that early tetrapods were well-established in Gondwana’s cold-temperate regions as early as the Carboniferous-Permian transition. 

“This discovery challenges previous beliefs about early tetrapod distribution and evolution, which were mostly based on fossils from the northern hemisphere,” Marsicano said. 

“Our research shows a well-established early Permian fauna, with Gaiasia as an apex predator, in rocks from high-latitude Gondwana, now located in central Namibia. This challenges previous ideas and proves that the early history of tetrapods in Pangea during the Palaeozoic was much more complex than we thought.”

The fossils have been returned to Windhoek, where they will soon be on display in the Geological Museum of Namibia.

Image Credit: Claudia Marsicano

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