Fossil site reveals giant arthropods that ruled the seas 470 million years ago

Fossil site reveals giant arthropods that ruled the seas 470 million years ago

Fossils from the Fezouata Shale. From left to right, an unmineralized arthropod (Marrellomorpha), a paleoscolecid worm, and a trilobite. Photo credit: Emmanuel Martin

Discoveries at a major new fossil site in Morocco suggest that giant arthropods — relatives of modern creatures like shrimp, insects and spiders — ruled the seas 470 million years ago.

Early evidence from the Taichoute site, once submerged but now a desert, shows numerous large “free-swimming” arthropods.

More research is needed to analyze these fragments, but based on previously described specimens, the giant arthropods could be up to 2m long.

An international research team says the site and its fossil record are very different from other previously described and studied Fezouata shale sites from 80km away.

They say that Taichoute (considered part of the broader “Fezouata Biota”) opens new avenues for paleontological and ecological research.

“Everything is new about this site – its sedimentology, paleontology, and even the preservation of fossils – further underscoring the importance of the Fezouata biota in completing our understanding of past life on Earth,” said lead author Dr. Farid Saleh from the University of Lausanne and the University of Yunnan.

dr Xiaoya Ma from the University of Exeter and Yunnan University added: “While the giant arthropods we discovered have not yet been fully identified, some may belong to previously described species of the Fezouata biota, and some will certainly be new species.”

Fossil site reveals giant arthropods that ruled the seas 470 million years ago

Large fragments of nectonic arthropods. Photo credit: Bertrand Lefebvre

“Nonetheless, their large size and free-swimming lifestyle suggest they played a unique role in these ecosystems.”

The Fezouata Shale was recently selected as one of the top 100 geological sites in the world for its importance in understanding evolution during the Early Ordovician, approximately 470 million years ago.

Fossils discovered in these rocks include mineralized elements (such as shells), but some also show exceptional preservation of soft tissues such as internal organs, allowing scientists to study the anatomy of early animal life on Earth .

Animals of the Fezouata Shale in Morocco’s Zagora region lived in a shallow sea subjected to repeated storm and wave activity that buried the animal communities and preserved them in place as extraordinary fossils.

However, nectonic (or free-swimming) animals remain a relatively minor component in the Fezouata biota overall.

The new study reports the discovery of the Taichoute fossils, preserved in sediments several million years younger than those from the Zagora area and dominated by fragments of giant arthropods.

Fossil site reveals giant arthropods that ruled the seas 470 million years ago

The newly discovered site from the Fezouata Shale. Photo credit: Bertrand Lefebvre

“Carcasses were transported to a relatively deep ocean environment by underwater landslides, which is in contrast to previous discoveries of carcass preservation in shallower environments that were buried in place by storm debris,” said Dr. Romain Vaucher from the University of Lausanne.

Professor Allison Daley, also from the University of Lausanne, added: “Animals such as brachiopods have been found on some arthropod fragments, suggesting that these large shells acted as nutrient reservoirs for the seabed-dwelling community once dead and on the seabed . “

dr Lukáš Laibl from the Czech Academy of Sciences, who had the opportunity to participate in the initial fieldwork, said: “Taichoute is important not only because of the dominance of large nectonic arthropods.

“New trilobite species are also being found in Taichoute that were previously unknown from the Fezouata biota.”

dr Bertrand Lefebvre from the University of Lyon, who is the lead author of the article and has been working on the fezouata biota for two decades, concluded: “The fezouata biota keeps surprising us with new unexpected discoveries.”

The paper published in the journal Scientific Reportsis entitled: “New Fossil Assemblages from the Early Ordovician Fezouata Biota”.

More information:
New fossil assemblages from the Early Ordovician Fezouata Biota, Scientific Reports (2022). DOI: 10.1038/s41598-022-25000-z

Provided by the University of Exeter

Citation: Fossil site reveals that giant arthropods dominated the oceans 470 million years ago (2022, December 13), retrieved December 13, 2022 from -arthropods.html

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