The rangeomorphs were members of the strange soft-bodied Ediacaran biota, which had a global distribution and predated the appearance of the more familiar shelly fossils of Cambrian times such as trilobites, brachiopods and molluscan bivalves and cephalopods.

 A new study by Jennifer Hoyal Cuthill and Simon Conway Morris, scientists from the Tokyo Institute of Technology and University of Cambridge, suggests that rangeomorph biology was sufficiently ‘plastic’ to rapidly achieve this step-change in size. Detailed measurements of the frond indicate that growth in size and shape was highly responsive to increases in ocean nutrients. Thus the sudden boom in size was probably in response to a change in ocean chemistry – perhaps an increase in oxygen.

Although fossil rangeomorphs and the other members of the Ediacaran biota have been known about for decades, their exact biological affinities are still a matter of intense research by University of Cambridge scientists.

Douglas Palmer, Sedgwick Museum 

The research is published in the journal Nature Ecology and Evolution 

Big, shape-shifting animals from the dawn of time