A new species called Gondwanascorpio emzantsiensis is now the oldest known land-living animal discovered in Gondwana. Dr. Robert Gess, from the Evolutionary Studies Institute at Wits University, discovered the 350 million year old fossilized scorpion from rocks of the Devonian Witteberg Group near Grahamstown.

Explaining his discovery, Gess said that early life was confined to the sea and the process of terrestrialization - the movement of life onto land - began during the Silurian Period roughly 420 million years ago. The first wave of life to move out from water onto land consisted of plants, which gradually increased in size and complexity throughout the Devonian Period. 

This initial colonization of land was closely followed by plant and debris-eating invertebrate animals such as primitive insects and millipedes. By the end of the Silurian period about 416 million years ago, predatory invertebrates such as scorpions and spiders were feeding on the earlier colonists of land.

By the Carboniferous period (350 million years ago), early vertebrates had in turn left the water and were feeding on the invertebrates. Although we knew that Laurasia -the single northern landmass then comprising what is today North America and Asia - was inhabited by diverse invertebrates by the Late Silurian and during the Devonian, this supercontinent was at the time separated from the southerly positioned Gondwana by a deep ocean.

Fossil showing the sting of the scorpion.Credit: Wits University

"Evidence on the earliest colonization of land animals has up till now come only from the northern hemisphere continent of Laurasia, and there has been no evidence that Gondwana was inhabited by land living invertebrate animals at that time," explained Gess. "For the first time we know for certain that not just scorpions, but whatever they were preying on were already present in the Devonian. We now know that by the end the Devonian period Gondwana also, like Laurasia, had a complex terrestrial ecosystem, comprising invertebrates and plants which had all the elements to sustain terrestrial vertebrate life that emerged around this time or slightly later."

Fossil showing the pincers of the scorpion. Credit: Wits University

Citation: Robert Gess, 'The earliest record of terrestrial animals in Gondwana: A scorpion from the Famennian (Late Devonian) Witpoort Formation of South Africa',  African Invertebrates Vol. 54 (2): 373–379 Pietermaritzburg 28 August 2013 (upcoming)