Charnia masoni

Foreword by Dr Francis Dunn

Charnia masoni was first described in 1958 by Dr Trevor Ford (University of Leicester) who was our recent Life President. The fossil had been independently discovered by two school children – Tina Negus and Roger Mason – in Charnwood Forest, Leicester, England. Tina Negus had been met with denial by her education staff, as then the held belief was that no life existed before the Cambrian. Later, Roger Mason, through his father, was able to reach Trevor Ford. C. masoni remains one of the most significant fossils ever discovered because it validated Charles Darwin’s theory of Evolution by Natural Selection, resolving ‘Darwin’s dilemma’. At the time that Darwin was writing, Earth history was split into ‘Phanerozoic’ – meaning 'visible life'; and ‘Azoic’ – meaning 'without life', which encompassed the vast stretch of time from ~4500 million years ago to 500 million years ago. If Darwin’s theory was to be correct, he predicted the presence of animals, fungi and other organisms, stretching far back into the ‘Azoic’, as evolutionary change through Natural Selection, occurred gradually. After the description of C. masoni, scientists came to recognise that there existed a global Ediacaran biota (after the time period – Ediacaran – in which Charnia lived), with fossils from Namibia, South Australia and Russia, all being redescribed as Ediacaran in age. A lot of these other fossils were known before Charnia masoni, but the rocks could not then be precisely dated, and so, following the prevailing wisdom at the time, they had been described as Phanerozoic. It became clear that some other members of the Ediacaran biota had anatomies very similar to C. masoni, and today we call this group the rangeomorphs, after Rangea, which was originally described in 1933. The rangeomorphs are sometimes called the ‘fractal fronds’ because they are constructed of extremely intricate, and hierarchically repetitive, branches. They look like nothing alive today, and do not appear to have any direct, living descendants. Because of this, understanding where they sit in the tree of life, or how they fed, has proved to be challenging, with arguments in the scientific literature going back and forth since the discovery of C. masoni; with people suggesting that rangeomorphs could represent animals, algae, fungi, and giant single-celled organisms called protists. One of the most original – and controversial – suggestions came from the German palaeontologist Dolf Seilacher, who suggested that C. masoni, and its near kin, were more closely related to each other than to anything alive today, and erected a new, and totally extinct, Kingdom of Life to put them in. He called this Kingdom the Vendozoa – vendo for Vendian, another word for Ediacaran, and zoa meaning life. Today, there are hundreds of known specimens of Charnia, from Charnwood Forest, Canada, Australia, Namibia, Russia and China. These specimens are preserved, slightly differently, but often record the communities in which they lived. This means that researchers are able to access information about how they grew and interacted with other species. Recent work has shown that the Charnia grow in a way which is like living animals, to the exclusion of other possibilities, and we now think that Charnia was a distant ancestor to all animals with tissues (including corals, insects, starfish and us!), telling us about one of the earliest stages in animal evolution. There is still much to uncover about Charnia, and other rangeomorphs, but with a growing international group of researchers seeking to answer these questions, we are finally beginning to unravel the mystery of the Ediacaran biota.

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Bradgate Park, North Leicester. Memorial Crags, at extreme left, are where Charnia masoni can be seen