The Early Ordovician Fezouata Biota of Morocco is an exceptionally preserved fossil collection containing a combination of non-mineralized extinct organisms. Pointing to a continuous evolutionary process between the Cambrian explosion and the Ordovician radiation, the finding of this biota fundamentally changed our understanding of the early diversification of Earth’s animals.

A new study reported the discovery of Taichoute, a new site of Fezouata shale fossils. Numerous huge “free-swimming” arthropods are documented in the earliest evidence of the Taichout site, which used to be submarine but is now a desert.

The research from an international research team, including the University of Exeter, suggests that giant arthropods – relatives of modern creatures such as shrimp, insects and spiders – dominated the seas 470 million years ago.

Scientists noted, “Tarthropods — relatives of modern creatures including shrimp, insects and spiders — dominated the seas 470 million years ago.”

Lead author Dr. Farid Saleh, from the University of Lausanne and the University of Yunnan, said: “Everything is new about this place — the sedimentology, paleontology, and even fossil preservation — further highlighting the importance of the Fezouata Biota for completing our understanding of past life on Earth.”

Dr. Xiaoya Ma, from the University of Exeter and the University of Yunnan, 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.”

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

In addition, the study also reports the discovery of the Taichout fossils. These fossils are preserved in sediments several million years younger than those from the Zagora area and are dominated by fragments of giant arthropods.

Because of its significance to understanding evolution during the early Ordovician period, some 470 million years ago, the Fezouata shale was recently chosen as one of the top 100 geological sites worldwide.

Some fossils in these rocks show excellent preservation of soft tissues, such as internal organs, allowing scientists to study the anatomy of early animal life on Earth. Mineralized materials, such as shells, are among the fossils found in these rocks.

Animals of the Fezouata shale, in the Zagora region of Morocco, lived in a shallow sea that often experienced storm and wave activity. The animal populations were buried as a result and are now preserved in situ as remarkable fossils. Nectonic (or free-swimming) animals, however, remain a minor part of the overall Fezouata Biota.

Dr. Romain Vaucher, from the University of Lausanne, said: “Carcasses were transported underwater to a relatively deep marine environment by landslides, which contrasts with previous discoveries of preservation of carcasses in shallower environments, which were buried in place by storm deposits.”

Professor Allison Daley, also from the University of Lausanne, added: “Animals such as brachiopods are attached to some arthropod fragments, indicating that these large shells acted as nutrient stores for the seafloor community once they were dead and on the seafloor.”

Dr. Lukáš Laibl, from the Czech Academy of Sciences, who had the chance to take part in the first fieldwork, said: “Taichoute is needed not only because of the dominance of large nektonic arthropods.”

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

Dr. Bertrand Lefebvre, of the University of Lyon, the paper’s senior author, who has worked on the Fezouata Biota for the past two decades, concluded: “The Fezouata Biota continues to surprise us with new, unexpected discoveries.”

Magazine reference:

  1. Saleh, F., Vaucher, R., Vidal, M. et al. New fossil assemblages from the early Ordovician Fezouata Biota. Sci Rep 12, 20773 (2022). DOI: 10.1038/s41598-022-25000-z