Our entire history of evolution is being rewritten with the discovery of Africa’s fish-with-legs.
Based at the Albany Museum in Grahamstown, paleo scientist Dr. Robert Gess made the groundbreaking discovery of one of Africa’s earliest four-legged creatures.
He discovered the remains of two tetrapods in the Devonian Waterloo Farm near Grahamstown University in South Africa.
The first discovery is a tetrapod represented by a single bone from the shoulder girdle named Umzantsia Amazana. Zantsia, meaning south or South Africa is fitting considering it was found in South Africa and it is from the very south (or late) portion of Devonian period. Amazana, meaning water ripples refers to its distinctive ornaments on its bone.
For reference, the Devonian period is categorized as being approximately 420 to 359 million years ago; all of today’s land vertebrates are descendants from Devonian tetrapods, like fish with legs.
The second discovery is called Tutusius Umlambo, named after Archbishop Desmond Tutu because it “led the way into the sunshine” from the cold waters. Umlambo has a greater number of bones, which indicates that it is younger than the aforementioned tetrapod and it evolved to better maneuver on land or shallow waters.
“When I was thinking about names for them, it occurred to me that these tetrapods led the way from these rather anoxic swamps out into the sunshine,” Gess says, “And it seems to me that in many ways, that was a metaphor for what Desmond Tutu had done.”
What Does This Mean For The Study of Evolution?
One of the most beautiful things about science is that it is constantly changing. What scientists originally thought was fact is being contradicted, and that is actually really exciting. There is still so much to learn as our knowledge of the world and universe is constantly expanding.
For the study of evolution, the discovery of these two ancient ancestors rewrites our entire history. Our understanding of the evolution of water organisms to land organisms is just now being fully realized.
The first appearance of tetrapods was nearly 70 million years than what scientists originally thought!
Not only that, but before Dr. Gess’s discovery, it was believed that fish with legs were solely found in the tropic.
“Whereas all previously found Devonian tetrapods came from localities which were in tropical regions during the Devonian‚ these specimens lived within the Antarctic circle‚” Dr. Gess explained
South Africa 400 million years ago was much like the Arctic and the grasslands that the nation is now famous for did not even exist yet.
As previously mentioned, Devonian tetrapods like Umzantisa Amazana and Tutusius Umlambo are the early ancestors of all land vertebrates. These old descendants are the direct link between fishes and animals, and they evolved in the fashion that they did to match the shifting environment.
Amidst a rather wet environment, fish and fish-like animals thrived. With the emergence of grasslands, an animal that appeared to be a mix between a crocodile and a fish appeared to sustain life in the shallow waters.
They had a crocodile-esque head, stubby legs and tail with a fish-like fin.
This is arguably the most important macroevolutionary changes in vertebrate history.
How Were These Discovered?
“I’ve slowly chiselled through 20 tons of that in the last 20 years. I have another 80 tons, and I’m almost certain there will be more [discoveries] as we go through the rocks.” Gess said in reference to the process he took on finding his discoveries.
When Gess was splitting rocks at Waterloo farm one day, he split open a rock that had a bit bone showing. Upon this realization, he met with other skeletal experts and found that that particular bone was the top of the shoulder girdle of a tetrapod; this truly distinctive bone is known as the cleithrum.
In celebration of Gess’s remarkable work, the Minister of Science and Technology, Mmamoloko Kubayi-Ngubane congratulated the professor for putting South Africa at the forefront of evolutionary studies.
Featured Image via Wikimedia Commons