{"id":3837,"date":"2022-03-09T10:00:00","date_gmt":"2022-03-09T10:00:00","guid":{"rendered":"https:\/\/modernsciences.org\/staging\/4414\/?p=3837"},"modified":"2022-02-22T09:05:46","modified_gmt":"2022-02-22T09:05:46","slug":"nerve-tissue-impressions-preserved-in-500-million-year-old-arthropod-fossils","status":"publish","type":"post","link":"https:\/\/modernsciences.org\/staging\/4414\/nerve-tissue-impressions-preserved-in-500-million-year-old-arthropod-fossils\/","title":{"rendered":"Nerve Tissue Impressions Preserved In 500-Million-Year-Old Arthropod Fossils"},"content":{"rendered":"\n

It\u2019s true that nature certainly seems relentless, in that it is only capable of preserving such a small slice of its otherwise vast amounts of life present at any given time as fossils; scientists must live with the fact that the animals and plants locked in stone that they find are just a handful compared to the rest that would have been around at the time.<\/p>\n\n\n\n

This, of course, doesn\u2019t discourage them from searching high and low for the remains of organisms that in some cases are hundreds of millions of years old. And, in rare cases, nature manages to preserve the organism in question in such fine detail that it\u2019s hard to imagine how it survived geological processes for so long for scientists to find it. You see this in remarkable fossil finds like ammonites with visible muscles<\/a> and ancient beetles with beautiful patterns still visible<\/a>.<\/p>\n\n\n\n

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One of the more stunning preserved invertebrate fossils is that of Aeger tipularius<\/em>, a fossil shrimp from the Jurassic Period. A. tipularius<\/em> was found within the limestone of Solnhofen\u2014the very same deposit that yielded the famous Archaeopteryx lithographica<\/em>.<\/figcaption><\/figure><\/div>\n\n\n\n

A remarkable find from reexamined fossil collections within Harvard University<\/a>\u2019s Museum of Comparative Zoology<\/a> (MCZ) and the Smithsonian Institution<\/a> had scientists study two tiny, unassuming fossils of 508 million-year-old ancient arthropods called Mollisonia symmetrica<\/em>, each one smaller than most medicine pills. The two ancient bugs, however, hid some startling detail: impressions of fossilized nerve tissue. The study detailing these findings were published in the journal Nature Communications<\/em><\/a>.<\/p>\n\n\n\n

\u201cIt is [\u2026] true that we do not have every single characteristic of the nervous system of this animal mapped out, because the fossils only tell us so much,\u201d said first author and curator of Harvard\u2019s MCZ Javier Ortega-Hern\u00e1ndez to LiveScience<\/a>. Additionally, they lament on the obfuscation of certain key features that, had they been clearer, would have helped Ortega-Hern\u00e1ndez and the team to locate M. symmetrica<\/em>\u2019s place in the tree of life.<\/p>\n\n\n\n

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The Smithsonian (a, b) and Harvard (c) specimens of Mollisonia symmetrica<\/em> reveal exquisite details about its nervous system\u2014parts of the body that are remarkably hard to find in fossils of this age and type. (Ortega-Hern\u00e1ndez et al, 2022)<\/figcaption><\/figure><\/div>\n\n\n\n

What remains remarkable, though, is the fact that these nerve impressions are actually still there, preserved despite the hundreds of millions of years since the animals died. These nerve tissue impressions included eyes and nerve cords.<\/p>\n\n\n\n

The two tiny fossils of M. symmetrica<\/em>, on the other hand, were actually obtained from the Burgess Shale<\/em><\/a>, a fossil deposit located in British Columbia that\u2019s known for its unique treasure trove of really ancient fossils from a time when life was locked in the seas. The Harvard fossil was locked in stone in such a way that you were viewing it from the top; the Smithsonian one, on the other hand, was fossilized lying on its side.<\/p>\n\n\n\n

Ortega-Hern\u00e1ndez recalls spotting something \u201cfunky\u201d while combing over the two M. symmetrica<\/em> specimens under a microscope, saying the nerve tissue impressions looked like \u201cblack splotches,\u201d in part due to the fossilization process transforming the tissue into films of organic carbon.<\/p>\n\n\n\n

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A closer inspection of the Harvard specimen of M. symmetrica<\/em> shows its distinct eye bulbs and part of its nerve cord. ((Ortega-Hern\u00e1ndez et al, 2022)<\/figcaption><\/figure><\/div>\n\n\n\n

The side-view Smithsonian fossil showed impressions of what was clearly an eye, while the Harvard specimen clearly shows both. Alongside it, the Harvard specimen apparently revealed a bit of its nerve cord; unfortunately, most of this cord was hidden within the predominant impression of its digestive tract.<\/p>\n\n\n\n

To Ortega-Hern\u00e1ndez and the team, these two stunning finds reveal partial details about M. symmetrica<\/em>\u2019s place in the family tree, specifically in the realm of the chelicerates<\/em>, a massive subdivision of the \u201cbug\u201d phylum Arthropoda<\/em>; modern-day chelicerates include scorpions, horseshoe crabs, ticks, and all living spiders.<\/p>\n\n\n\n

To them, while the details aren\u2019t enough to fully determine whether its branch in the tree of life brings it closer to more ancient or more modern chelicerates, the team believes that the discovery of even better-preserved specimens of Mollisonia<\/em> may finally reveal insights about its nervous system, and how that links to the condensed brains we see in modern-day chelicerates today.<\/p>\n\n\n\n

References<\/h2>\n\n\n\n