The fossil site reveals that giant arthropods dominated the seas 470 million years ago

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

Early evidence from the once-submarine but now deserted Taichoute site records 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 2 meters long.

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

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

“Everything is new in this locality – its sedimentology, paleontology and even the conservation of fossils – further highlighting the importance of the Fezouata Biota in complementing our understanding of past life on Earth,” said lead author Dr. Farid Saleh , the University of Lausanne and the University of Yunnan.

Dr Xiaoya Ma, from the University of Exeter and the University of Yunnan, added: ‘Although the giant arthropods we have discovered have not yet been fully identified, some may belong to previously described species from the Fezouata Biota, and some will definitely be new species.

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

The Fezouata Shale was recently selected as one of the world’s 100 most important geological sites due to its importance for understanding evolution during the Early Ordovician Period, approximately 470 million years ago.

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

The animals of the Fezouata Shale, in the Zagora region of Morocco, lived in a shallow sea that experienced repeated storm and wave activity, which buried the animal communities and preserved them in place as exceptional fossils.

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

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

“The hulks were carried into a relatively deep marine environment by underwater landslides, which contrasts with previous findings of the preservation of hulks in shallower environments, which were buried in place by storm surge deposits,” said Dr. Romain Vaucher, of the University of Lausanne.

Professor Allison Daley, also of the University of Lausanne, added: ‘Animals such as brachiopods are found attached to some arthropod fragments, indicating that these large carapaces served as nutrient depots for the community living on the seabed once once they were dead and lying on the seabed.”

Dr. Lukáš Laibl of the Czech Academy of Sciences, who had the opportunity to participate in the initial fieldwork, said: ‘Taichoute is not only important for the dominance of large nektonic arthropods.

“Even when it comes to trilobites, new species hitherto unknown from the Fezouata Biota are found in Taichoute.”

Dr Bertrand Lefebvre, of the University of Lyon, who is the lead author of the paper and who has been working on Fezouata Biota for the past two decades, concluded: ‘Fezouata Biota continues to surprise us with unexpected new discoveries.’

The document, published in the magazine Scientific reportsis titled: “New Fossil Assemblies from Early Ordovician Fezouata Biota.”