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A Canadian-led study aims to settle the controversy over extraordinary Arctic fossils that represent the oldest known sexually reproducing organism and the oldest multicellular organism that used photosynthesis. The fossil organism identified as a red algae called Bangiomorpha pubescensfound in rocks on Somerset Island and Baffin Island in Nunavut, was discovered more than two decades ago and estimated to be between million and 1.
But the fact that its age could have been anywhere in a million year span led to some controversy. Some scientists' calculations based on DNA evidence suggested red algae couldn't have existed 1. And being on the younger end of the range would have put its age as being similar to other fossils of recognizable complex organisms, making it nothing unusual.
Now researchers from McGill University, using a relatively new radiochemical dating technique, have estimated that the fossils are between 1.
The fact that they're ificantly less than 1. But the fact that it's more than a billion years old means that it's still by far the oldest recognizable multicellular complex organism.
Knowing precisely how old the fossil is also allowed the researchers to estimate that the very first plant likely evolved around 1. Bangiomorpha, a microscopic fossil organism just fractions of a millimetre long, was first discovered beautifully preserved in layers of chert — effectively, glass — in cliffs on Somerset Island in Nunavut. It was described by British scientist Nick Butterfield in He named it:.
The fossil was extraordinary because it was found in a rock formation up to 1.
Roger researches the diversification of life more than a billion years ago and the evolutionary rise of complex organisms. In anhe said people were skeptical that Bangiomorpha was really a red algae fossil because it was so old and there weren't any other eukaryotes similar to the ones who live today in the fossil record from that time. The reason it was so hard to tell how old Bangiomorpha was is that to measure the age of rocks, geologists typically rely on chemical techniques that can only be applied to layers of volcanic rock, Gibson said, and there wasn't much of that in the cliffs where the fossils were found.
So Gibson and his supervisor, Galen Halverson, decided to use a relatively new technique called Rhenium-Osmium dating that works well in rocks containing a lot of organic carbon, like the shale that the fossils were sandwiched between in cliffs on Baffin Island where they had also been found. Working up there was a "dream come true" for Gibson: "It's a magical place I've wanted to go for a long time. For four summers, he and a small team helicoptered in to sites between Pond Inlet and Arctic Bay.
They camped on the tundra in lightweight tents at the tops of sea cliffs to avoid polar bears, then scrambled down to collect samples with simple rock hammers. Once back at the lab, the researchers measured the amount of radioactive rhenium, a rare radioactive isotope found in seawater that accumulates in organic matter and decays to osmium Very little osmium is found naturally in rocks. So by measuring the ratio of rhenium to osmium, scientists can tell how long the rhenium has been decaying in the rock and therefore how long it's been since the rock formed.
The new, precise date estimate for Bangiomorpha can now be plugged into computer models of evolution that estimate when different species evolved based on mutation rates in their DNA called "molecular clocks. Gibson and his colleagues did that to estimate that the first photosynthetic eukaryote evolved around 1. Roger says the new, more precise age for Bangiomorpha measured by Gibson, Halverson and their colleagues is "definitely important — but it doesn't completely solve the problem.
He said he still Sex dating in Fossil it "very concerning" that no other fossils of recognizable complex organisms besides Bangiomorpha older than million years have been found to date. Molecular clock estimates of events in early evolution often have extremely large error bars — sometimes spanning hundreds of millions of years — partly because the fossil record from that time is so incomplete, he added. They'll only improve when more very ancient fossils are found.
A few years ago, Roger notes that he and some colleagues did their own molecular clock analysis that suggested plants emerged earlier than Gibson and his colleagues calculated. Science Fossils of earliest organisms that had sex are a billion years old A Canadian-led study aims to settle the controversy over extraordinary Arctic fossils that represent the oldest known sexually reproducing organism and the oldest multicellular organism that used photosynthesis.
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Flies having sex preserved in fossil dating back millions of years