Dr Robert Gess, a postdoctoral fellow from the Evolutionary Studies Institute at Wits University has discovered a 350-million-year-old fossilized scorpion from rocks of the Devonian Witteberg Group near Grahamstown, in South Africa's Eastern Cape.

Gess unearthed the fossilized pincer and the tail segment and sting when breaking small slabs of shale from the site. Both the fossils were found separately, and do not belong to the same individual. The small, predatory creatures were estimated to be the size of a modern-day pencil.

"They are very delicate, and silvery-white in colour against the dark background of the rock," Gess said.

The scorpion, named as Gondwanascorpio emzantsiensis, is considered to be the oldest known land animal to have lived on Gondwana during a geological period called the Devonian.

During the Devonian period, between 420 and 360 million years ago, the world comprised of two supercontinents: Laurasia - North America, Europe and Asia; and the Gondwana - Africa, South America, Australia, Antarctica and India. The two land mass were separated by a deep ocean.

"Evidence on the earliest colonisation 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,"said Gess.

"There has been no evidence that Gondwana was inhabited by land living invertebrate animals at that time," said Gess.

By the end of the Silurian period, about 416 million years ago, predatory invertebrates such as scorpions and spiders were feeding on primitive insects and millipedes.

Laurasia was also known to comprise of invertebrates by the late Silurian and during the Devonian period, when it separated from Gondwana.

"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," said Gess.

The discovery is published in the peer reviewed journal African Invertebrates.

Apart from the scorpion fossils, Gess also discovered 20 types of fish and a range of different land plants.