Scientists believe that they have found what represents Africa’s earliest known land ecosystem
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Johannesburg - They would have provided a splash of greenery in a somewhat barren landscape not unlike that of Mars.
These plant species would have hugged the water’s edge and the tallest of them would have only reached ankle height, that is if humans were around then.
But what these plants were, were pioneers from which the land flora we know today would spring. They lived in what is now the Humansdorp area in the Eastern Cape, 420 million years ago, when the earth was a harsh place, devoid of even soil.
It was a geological time known as the Devonian, when South Africa wasn’t where it is today, but sat close to the Antarctic circle. Temperatures, however, would have been warmer than today.
The imprints these plants left behind have survived and recently were discovered by Dr Rob Gess of the Albany Museum’s Devonian Lab, situated in Makhanda, in the Eastern Cape. The fossils were found at a new dig site, he had discovered.
Now scientists believe that this find represents Africa’s earliest known land ecosystem and provides a peek into a time when life was beginning its march from the briny oceans onto land.
In a recent article published in the journal Scientific Reports, Gess and co-author Dr Cyrille Prestianni, of the Royal Belgian Institute of Natural Sciences, were able to pick out 15 plant species, three of which were unknown before.
But these plants are very different from what we know today. At the time, leaves had yet to evolve and plants didn’t have deep complete root systems.
Instead these plants were branching stalks on which sat spore containers.
“Some resembled miniature vuvuzelas, balls, clubs and some were castanet shaped,” explains Gess.
What Gess hasn’t found as yet are any animals that might have lived amongst these plants. He suspects that small invertebrates were there and that it is a matter of time before he finds them in the fossil record.
The seas, however, would have teemed with life, including early fish that had only just evolved jaws and a host of invertebrates.
Until Gess’s discovery only one species of plant from this age had been discovered in South Africa, and that was nearly 90 years ago.
It is an indication of just how rare these fossils are.
There are only 23 fossil sites around the world that have produced plants from this time.
And most of the fossils found, says Gess, contain the imprints of individual plants.
What also makes the new find important is that here is an example of an ecosystem from a high latitude near polar zone. Previous finds came from what was then the tropics.
Two hundred kilometres away on the outskirts of Makhanda, Gess has another dig site that he has been working on for years.
Here he has found fossils that are 60 million years younger than the ones discovered near Humansdorp. They still fall within the Devonian, but in paleo terms 60 million years is a blink of an eye.
When Gess compared what he had found at the two sites, it revealed just how quickly life established itself on land.
“So we go from really primitive ankle high green fuzz around the edges of lakes, lagoons, and 60 million years later we have lovely cool shaded forests,” explains Gess.
By then the land had been populated by a host of invertebrate animals.
Tetrapods, that had crocodile-like heads with short legs and a broad flat tail, still largely lived in shallow water but may have ventured out from the water onto land to feed on insects and scorpions. It would only be in the future when they left the water’s edge for good.
Gess’s discovery is a boon for South Africa, explains retired palaeontologist Professor Bruce Rubridge.
“It's hugely exciting from a scientific perspective, and it puts South Africa on the map for what is happening four to 500 million years ago, on how plants developed on Earth,” says Rubridge.
“Rob is working in a time period which has been little worked on in South Africa.”
It is likely that in those oceans would have lurked an ancestor to humankind. Hundreds of millions of years in the deep past would have made in unrecognisable to humans today.
“At the beginning of the Devonian it would have been a really primitive fish, but 60 million years later it would have had legs with fingers and toes. And it would have lost the fin on its back and would have been wandering around the shallows, with eyes on the top of its head,” says Gess.
By understanding the ecosystems that were evolving on land at the time, it will help scientists to understand the steps those ancestors took from the water on that long march to becoming us.