What is Cambrian Mega Value

Shapeshifters were the first megafauna on earth

Cambridge / Tokyo - There are worlds between a 30 meter long blue whale and its preferred prey - crabs a few millimeters in size. Researchers at Cambridge University and the Tokyo Institute of Technology investigated the question of how and why the animal world produced giants by taking a look back in time: to the Ediacarium, which, as far as we know today, was the first age in which the multicellular organisms developed something like a megafauna.

In this age 635 to 541 million years ago, the Rangeomorpha were a formative phenomenon worldwide. They sat on the seabed with an adhesive disc and stretched their soft, fern-frond-like bodies upwards, with which they must have filtered food particles out of the water. Some of them were only a few centimeters tall - still considerable for the time - while others reached heights of almost two meters. They were the giants of their time. However, it is still a matter of dispute whether they were actually animals.

Complexity and flexibility

The structure of the Rangeomorpha was very interesting, report the researchers working with Jennifer Hoyal Cuthill from the University of Cambridge in the journal "Nature Ecology and Evolution". The branches of the fan-shaped body, in turn, had small side branches - a fractal structure.

The researchers were particularly interested in why organisms that cannot be compared to anything alive today entered the stage of life "with a bang": Even the oldest Rangeomorpha fossils found so far were much larger organisms than the other sea creatures of their time . Rangeomorpha fossils from Newfoundland, Great Britain and Australia were examined using X-ray microtomography to answer this question.

The researchers came to the conclusion that the Rangeomorpha could easily produce a complex body due to their special structure. Size and shape were variable - Cambridge University speaks of "shape-changing animals". And that gave them a high degree of flexibility in order to react to environmental conditions: for example, to grow rapidly in height if this enabled them to reach an oxygen-rich water layer.

Changing world

Hoyal Cuthill suspects that during the mega-ice age that preceded the Ediacarian, the bodies of animals were kept small because there was little oxygen and nutrients available in the water. In the Ediacarium itself there were then great changes of as yet unexplained origin. The climate and ocean chemistry changed and may have enabled the formation of large bodies for the first time. (red, July 15, 2017)