In the last 150 years, scientists have strongly argued on a mysterious creature that lived hundreds of millions of years ago, before dinosaurs walked the Earth. And now, with the discovery of stunning fossils in Morocco, paleontologists have noted the strange forms of life.
The creatures, known as stylophorans, looked like flat and flattered wall decorations that had a long arm pushed off their side. But although they were not blurred before they fit into the family tree, the new study revealed that they were echinoderms, ancient ancient animal relatives such as sea barrage, seabed star, fragile stars, sea lilies, feather stars and sea cucumbers.
The finding was made possible thanks to fossils with "unlikely evidence for extremely soft soft parts, in the appendix and the body of stylophorans," said lead researcher Bertrand Lefebvre, researcher of the National Research Research Research Center (CNRS) at the Laboratory of Lyon geology in France. [Photos: Trove of Marine Fossils Discovered in Morocco]
The incredible fossils were found during an excavation in 2014 in Fezouata Form, along the Sahara desert in southern Morocco. The excavation of fossil fossils, including about 450 stylophoran specimens, led to approximately 478 million years ago.
But the researchers did not realize immediately that some of the fossils contain soft tissues that have been saved. "Only when we have been unpacked and looked under the boxes [microscope], back at the laboratory in Lyon, we could see the soft parts, "Lefebvre told Live Science in an email." Their presence and identification were subsequently confirmed by SEM observations and analyzes (electron scanning microscope). "
The discovery of soft tissue was unprecedented. Stylophoran fossils have been found worldwide since the 1850s, allowing researchers to decide that these creatures live from the Cambrian center to late Carboniferous periods, or about 510 million to 310 million years ago. behind, when the creatures disappeared. But because soft tissue rarely fossil, the stylophorans were only known of hard skeletal parts, and not their wet holes.
"Their internal anatomy was not only completely unknown, but also – and mainly – very controversial," said Lefebvre.
What did they look like?
Stylophorans had two main parts: a core body and a curious attachment attached to it. The core body and the attachment were small, all about 1.2 inches (3 centimeters) long, Lefebvre said.
Previously, other researchers came up with all kinds of ideas about stylophorans.
From 1850s to 1950s, most researchers believed stylophorans were "normal" echinoderms. Its bizarre appendix was interpreted as one that is equivalent to the strands of the sea.
Common echinoderms have internal skeletons made of oxygen plates, calcic (although this is being significantly reduced in sea cucumbers) and water vascular systems known to help them move and breathe, says Peter Van Roy, paleobiologist at the University of Ghent in Belgium, who was not part of the study.
Most echinoderms, including sea star, have five-ray symmetry. They belong closely to another group of invertebrates, the oystice worms, and to vertebrates (animals with backstones). Together, echinoderms, worms and vertebrates form an overarching group of the deuterostomia, said Van Roy. [Deep-Sea Creepy-Crawlies: Images of Acorn Worms]
Then, in the early 1960s, the paleontologist of the Belgian Georges Ubaghs commented that the appendix was different from a leg but similar to a feeding arm, as seen in a modern sea star.
In the late 1960s, Richard Jefferies, British paleontologist, offered a completely different idea. It was of the opinion that the main body of the stylophoran was end (holding pharynx and brain) and that the muscles were kept in the appendix and chemistry (primitive vertebral type). Jefferies thought that the "missing loop" was stylophorans between echinoderms and chordates (a group that includes vertebrates).
In the 2000s, Andrew Smith, British paleontologist, suggested another interpretation again. He said that the stylophorans did not seem to be "missing contact" between echinoderms and vertebrates but were more likely to be primitive deuterostoms, filling the gap between acorns and echinoderms.
The new discovery of the fossil soft tissue, however, has changed everything. Researchers could prove, for the first time, whether the soft tissue corresponds to what you would expect from any of these different scenarios, Lefebvre said.
The new fossils fit closer to Ubaghs' interpretation. The flat bodies of the stylophorans contained bowels, and the appendix was not blocked as a gun rather than looked like a sea star arm. This arm contained a water vascular system that would have helped the creatures move and eat, just like serenfish arms, says Van Roy.
Because there are no five-ray symmetry on stylophorans, they are likely to lose that, making them more "advanced" in evolution than other ray-five echinoderms, Van Roy added.
"This discovery is of special importance, as it ends a 150-year-old debate about the situation of remarkable fossils in the tree of life," said Lefebvre.
The study is "very thorough," said Van Roy, "and I do not have any doubts about any of the methods used or collections." In addition, it highlights the importance of well-preserved fossils from the Fezouata Form, where Van Roy has discovered spectacular specimens of that and so on.
The study was published online in the February issue of the Geobios magazine.
Originally published on Living Science.