The two new species, named Tutusius umlambo, after Archbishop Emeritus Desmond Tutu, and Umzantsia amazana, are Africa's earliest known four-legged vertebrates at 360-million years old, 120-million years older than the first dinosaur discoveries in the region.
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. The researchers think they had heads like crocodiles and tails like fish.
Although Waterloo Farm wasn't frozen back in the ancient Devonian period-which stretched from 420 to 360 million years ago-it still faced nights that lasted for weeks in the dead of winter. The Tutusius reportedly named after Desmond Tutu, the Human Rights activist and South African Anglican cleric, measured near about one meter in length.
A reconstruction by the Centre of Excellence in Palaeosciences of the University of the Witwatersrand showing Tutusius and Umzantsia.
"So we now know that tetrapods, by the end of the Devonian, lived all over the world, from the tropics to the Antarctic circle", said paleontologist Robert Gess "So it's possible that they originated anywhere and that they could have moved onto land anywhere".
Artist’s illustration of the two newly discovered Tutusius and Umzantsia that lived about 360 million years ago
The Waterloo Farm fossil site was revealed in 1985 after controlled rock-cutting by the South African National Roads Agency (Sanral) along the N2 highway south of Grahamstown.
This cutting exposed dark grey mudstones of the Witpoort Formation that represent an ancient environment of a brackish, tidal river estuary and contain abundant animal and plant fossils.
At the same time, "Umzantsia" refers to the southern region where the species was found and "amazana" means "water ripples", pointing to the "very distinctive ornaments on the bone", says the paleontologist. Most were discovered in what was once Laurussia, which broke into North America, Greenland and Europe. Because Australia was the northernmost part of Gondwana, extending into the tropics, an assumption developed that tetrapods evolved in the tropics, most likely in Laurussia. Attempts to understand the causes of these major macroevolutionary steps therefore focussed on conditions prevalent in tropical water bodies.
However, a remarkable new finding shows that tetrapods were widespread, and even inhabited the Antarctic Circle. But in the late Devonian-early Carboniferous period, the climate became more severe and occurred in the past.
The newfound fossils are the first ones ever to emerge from the south of the Devonian world (not just the south of Africa) and bring up the total of known tetrapod species to 13.
"There is probably not another country that so fully documents the long and dramatic evolutionary history of our own lineage", Gess said.