Dr Gess’ research has now been published, leading to a re-evaluation of scientists’ understanding of evolution. The fossils were of prehistoric Devonian Period amphibians believed to be the earliest known four-legged vertebrates. Described as resembling a cross between an alligator and a fish, these amphibians were the first to colonise the land and are therefore known as the ancestors of all vertebrates.
Until now, the consensus was that their evolution took place in warm tropical places, but the South African fossils indicate that they have also resided in colder environments, specifically within the Antarctic Circle, some 360 million years ago.
Devonian tetrapod fossils are found almost everywhere in the world. However, they were not found in ancient supercontinent Gondwana, which, in the present day, became Africa, South America, Australia, Antarctica, and India. The only fossil found of these amphibian tetrapods was a jaw and footprints in eastern Australia. Most of their fossils, were discovered on the ancient supercontinent called Laurussia, which includes today’s North America, Greenland, and Europe.
“Whereas all previously found Devonian tetrapods came from localities that were in tropical regions during the Devonian, these specimens lived within the Antarctic Circle,” the study states. The team therefore concluded that while tetrapods occurred in the world by the Late Devonian period, their evolution and migration to land could also have happened elsewhere in the world.
The fossils, named Tutusius umlambo (named after Archbishop Emeritus Desmond Tutu) and Umzantsia amazana, mean their terrestrialisation could have happened anywhere. In an interview, Gess explained that when naming the creature, Desmond Tutu came to mind because this was the type of creature that “ultimately pioneered the way for our ancestors up out of a somewhat anoxic, dangerous, swampy world into the sunshine and a bright new future”.
The two new species are Africa’s earliest known four-legged vertebrates, 120-million years older than the first dinosaur discoveries in the region. The 1m-long Tutusius, and the somewhat smaller Umzantsia are both incomplete fossils. Tutusius is represented by a single bone from the shoulder girdle, whereas Umzantsia is known from a greater number of bones, but they both appear similar to previously known Devonian tetrapods.
South Africa holds one of the most comprehensive databases of human evolutionary history in the world. This includes the Cradle of Humankind, the world’s richest early hominid site, which is home to around 40% of the world’s known human-ancestor fossils. This latest finding adds even more depth to the country’s history, making South Africa one of the most abundant archaeological sites in the world.