The Ediacaran enters the tree of lifeThis is a fossil of Dickinsonia, one of the more iconic members

The Ediacaran enters the tree of lifeThis is a fossil of Dickinsonia, one of the more iconic members of what is known as the Ediacaran fauna. The Ediacaran is the time period in Earth’s history from 634 to 542 million years ago, after the breakup of the possible snowball Earth events but prior to the start of the Cambrian, where organisms developed the use of hard parts and shells. Sedimentary layers from the Ediacaran don’t contain shells, but they do contain fossils like this bizarre creature; a mostly flat, segmented organism that has been found in samples up to 1.5 meters in diameter. Although there are many different organisms represented in the Ediacaran, there have been very few links uncovered between Ediacaran organisms and modern clades. These organisms are poorly enough understood that literally within the last few years scientists have argued whether they represent animals, plants, or fungi. A paper published last year argued that this specific organism grew by gradually adding segments and that behavior was characteristic of animals, but that classification still left its position on the tree of life uncertain. A new study finally may give this organism and other members of the Ediacaran biota a proper home.The key to solving the mystery of Ediacaran life is the Chengjiang lagerstaate (More here: https://tmblr.co/Zyv2Js23LRNr9). A lagerstaate is a unit of exceptional preservation where, due to sedimentary settings such as a lack of current and nothing in the soil eating dead organisms, even the soft tissues of organisms can be fossilized and preserved.A pair of scientists led by a researcher at the Tokyo Institute of Technology’s Earth-Life Science Institute examined 206 fossils of an organism called Stromatoveris psygmoglena from the Chengjiang Lagerstaate. Previous work has characterized this organism as an early metazoan – one of the main groups in the animal kingdom and a group including, well, us. By comparing morphological and growth features between this organism and several groups of related Ediacaran fossils, they argue that the organisms represent a single clade on the tree of life. The organisms have commonalities between their branch points, symmetries, body cavities, and stems – all suggesting the organisms share a common ancestor. This classification extends to a variety of Ediacaran fossil body types, including Dickinsonia.This work, therefore, not only places fossils like Dickinsonia into the animal kingdom, it gives them a proper location as a clade developing alongside others such as corals, it pushes the date for development of metazoans all the way back into the Ediacaran, and it verifies that some groups of Ediacaran organisms were able to continue thriving for tens of millions of years after the start of the Cambrian. Really cool stuff!-JBBImage credit:https://en.wikipedia.org/wiki/Dickinsonia#/media/File:DickinsoniaCostata.jpgOriginal paper:https://onlinelibrary.wiley.com/doi/full/10.1111/pala.12393References:https://www.paleowire.com/just-out-cambrian-petalonamid-stromatoveris-phylogenetically-links-ediacaran-biota-to-later-animals-palaeontology/https://blogs.scientificamerican.com/artful-amoeba/were-weirdo-ediacarans-really-lichens-fungi-and-slime-molds/http://www.ucmp.berkeley.edu/vendian/ediacaran.phphttp://www.ucmp.berkeley.edu/phyla/phyla.html -- source link

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