Dr Robert Gess, a South African scientist working in a remote part of the Eastern Cape has today unveiled ground-breaking research on fossils which represent the earliest record of a terrestrial (land living) animal in Gondwana. This is a 360 million year old scorpion from the Late Devonian, a time when the movement of life onto land was still occurring. Gondwana was a giant ancient continent made up of the land masses now known as South America, Australia, Antarctica, India and Madagascar.
The discovery, made during Wits University funded research, was published in the peer reviewed journal African Invertebrates, and consists of fragments of a new species of scorpion (the first Palaeozoic scorpion known from Gondwana).
Dr Robert Gess is excited and rightly so. The discovery comes from shale rocks at Waterloo Farm near Grahamstown in the Eastern Cape of South Africa, close to where he lives. This site has yielded many important fossils to Dr Gess’ painstaking excavations, including the world’s oldest fossil lamprey, which he discovered whilst doing his Phd, and which was published in 2006 in the journal Nature.
“Of course there must have been other terrestrial invertebrates around as scorpions are predatory” acknowledges Gess. “Scorpions, primitive insects and millipedes are known from older rocks in Europe and North America, but this is the oldest record from Gondwana - the first page in the story of terrestrial life in Gondwana”.
Devonian specimens from Australia (also once part of Gondwana) which were thought to be millipede remains were misidentified at the time by scientists and later found to be the remains of aquatic invertebrates.
Gondwanascorpio emzanziensis as the new species of scorpion is known, is therefore the oldest known terrestrial animal from Gondwana.
In his paper Gess refers to earlier described terrestrial invertebrates from lower Karoo Supergroup rocks, which were formerly Africa’s oldest terrestrial invertebrates, but which are a staggering 90 million years younger than this discovery.
Dr Gess says that although tetrapods (four legged vertebrates) were around in the water during the Late Devonian, they are believed to have only ventured onto land later (during the subsequent Carboniferous Period) to feed on terrestrial invertebrates that had already established themselves.
The unknown chapter which this discovery opens is an understanding of the land based invertebrates already living in Gondwana. The earliest land living tetrapods are as yet unknown from Gondwana but conditions were right for their being here.
“Until now we had no evidence that the early vegetation of Gondwana was also inhabited with invertebrate animals. For the first time we know for certain that not just scorpions, but whatever they were preying on, were already present during the Devonian. We now know that Gondwana, like Laurasia (the single landmass then comprised of North America, Europe and Asia), had a complex terrestrial ecosystem comprised of invertebrates and plants, by the end the Devonian. It too therefore had all the elements to sustain terrestrial vertebrate life (our four legged ancestors) that emerged around this time or slightly later.
Putting this all into perspective Dr Gess explains: “The first wave of life to come from the water onto land consisted of plants, which gradually increased in size and complexity throughout the Devonian Period. These were closely followed by plant- and debris-eating invertebrates such as primitive insects and millipedes. By the end of the Silurian, predatory invertebrates such as scorpions were feeding on the earlier colonists. In the earliest Carboniferous, early vertebrates had in turn left the water and were feeding on the invertebrates.”
*Fittingly, Dr Robert Gess, whose research now unveils for us the living world of hundreds of millions of years ago, dedicates this work to his father, Dr Fred Gess, one of South Africa’s leading entomologists who invested more than 50 years in the study of insect life as we know it in South Africa today. Formerly based at the South Africa’s oldest Natural History Museum Dr Fred Gess passed away on 6 August 2013.