26 April 2018 Photo Supplied
Pretzel-formed fossil of great evolutionary interest
Slab with holotype of Parapsammichnites pretzelifornic from the Urusis Formation, Namibia. Scale bar is 1cm.Picture was taken from Buatois et al., 2018.

The acclaimed scientific journal, Nature, recently published an article about a trace fossil in approximately 543-million-year-old rocks, which elucidates the evolution of the first animals that appeared on Earth and lived in the sea.  

Affiliated Professor in the Department of Geology at the University of the Free State (UFS) Prof Gerard Germs formed part of a team that conducted research with the aim of understanding how the evolution of the first multicellular animals came about and how the Cambrian explosion took place. Prof Germs is of great value to the team for his extended field geological knowledge.

An article which he co-authored was published in the Nature Scientific Reports. The title of the article is: “Sediment disturbance by Ediacaran bulldozers and the roots of the Cambrian explosion”. The international group of writers included authors from Canada, Spain and South Africa. 

Occurrence of the Cambrian explosion
Prof Germs explains the Cambrian explosion: “During the long (4.5-billion-year) history of the Earth, the first life originated and subsequently evolution of plants and animals took place from one-cellular organisms to multicellular vertebrate animals and seed plants. Approximately 573 million years ago the first multicellular animals appeared on the scene. Sometime afterwards, approximately 540 million years ago, a kind of explosion in the origin of many new animal species occurred. This explosion is known as the Cambrian explosion.”

The team studied Earth sediments which are somewhat older than the Cambrian explosion. Such sediments are approximately 573 to 541 million years old and form part of the Ediacaran (late Neoproterozoic) period.

“My discoveries of the past, of among others, the oldest animal with a carbonate skeleton (Cloudina) and of complex horizontal Cambrian-type “worm” tracks (treptichnids) in Ediacaran sediments of Namibia have demonstrated that the Cambrian explosion occurred more gradually than previously thought. This has recently been confirmed in the article that was published in the Nature Scientific Reports.”

Pretzeliformis bulldoze to search for food
According to the article there is evidence that   during the Ediacaran period   worm-like animals such as the Parasammichnites pretzeliformis were already so far developed that they, due to coelom development and size increase, for the first time in the history of the Earth, were able to disturb and bulldoze sediments.  In this way they were able to find a new food source in sea sediments. Bulldozing animals were previously thought to have originated only during and after the Cambrian explosion and not during the older Ediacaran.

“Another major aim of my cooperative research is to improve our knowledge of the geology of the Ediacaran to early Cambrian of South Africa and Namibia. We also intend to establish how the assembly of the supercontinent Gondwana took place. This improved knowledge can be of great future economic interest since large oil, gas and limestone sources occur in Ediacaran-age sediments outside South Africa”.

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