One of the world’s richest and most diverse fossil sites from the lower Ordovician period (488–444 million years ago) has been unearthed in southern France.
400 well-preserved fossils dating back 470 million years were found in Montagne Noire. The new fossils were analysed by scientists from the University of Lausanne and their colleagues at the CNRS (Centre National de la Recherche Scientifique) and internationally.
The results are detailed in a paper published in the journal Nature Ecology & Evolution.
Southern France was close to the south pole during the Ordovician, having moved north due to continental drift in the last few hundred million years. It gives a rare glimpse into the polar ecosystems of the Ordovician.
Shell-like components are accompanied by extremely rare soft tissue fossils such as digestive systems and cuticles. The fossils come from a time ‘only’ 70 million years after the so-called “Cambrian explosion” which saw the emergence of most of the major animal body plans.
The fauna present are arthropods (the group of animals which includes insects, spiders, scorpions and shrimp), cnidarians (which includes jellyfish and corals), algae and sponges.
High biodiversity suggests the area was an ancient refuge for species escaping hot conditions further north.
“At this time of intense global warming, animals were indeed living in high latitude refugia, escaping extreme equatorial temperatures,” says first author Farid Saleh.
Understanding how organisms responded to extreme climate conditions in the past could give us an insight into a possible future under climate change.
The two amateur palaeontologists who discovered the site are Eric Monceret and Sylvie Monceret-Goujon.
“We’ve been prospecting and searching for fossils since the age of twenty,” says Monceret. “When we came across this amazing biota, we understood the importance of the discovery and went from amazement to excitement,” adds Monceret-Goujon.