Organic microfossils from the Ediacaran of Estonia—behind the scenes

• When seeing a play, one easily gets caught by everything therein; the music, the dancing, and of course, the story. Still, most of the work took place before it even had its premiere. When the evolutionary curtain was lifted for most of the animals back in the beginning of the Cambrian, it had been preceded by many hundreds of millions of years of preparation. Still, as for any play, it was in the very last few moments that everything was coming together, that the scene became set. Hence, if we truly want to understand the events that was about to happen, we should peek behind the curtain before act one, into the Ediacaran Period and on its very busy little stage workers: the acritarchs. In order to better understand the dynamics of acritarch evolution at the Ediacaran-Cambrian transition two drill cores of allegedly Ediacaran age were studied. The drill cores had been taken in northern Estonia, and a total of 48 samples were prepared with the purpose of identifying the acritarchs and other organic microfossils using light microscopy. However, despite a relatively high taxonomic diversity, the recovered associations were strikingly different from other well-described Ediacaran acritarch faunas, most prominently by the absence of the large acanthomorphic acritarchs known from Australia, China and Siberia. Equally absent were the much smaller acanthomorphic acritarchs, characteristic of Cambrian sediments. Instead, a number of smooth-walled leiospheres was found to dominate the associations together with a variety of different types of filaments as well as unusually shaped fragments from yet unidentified organisms. It seems that the acritarchs were more than just stage workers: they had their own play going on, and this play appears to have been full of surprises.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Annan geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Other Earth and Related Environmental Sciences (hsv//eng)

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