in new paper in diary natural ecology and evolution, paleontologists described the diversity of the Cabrières biota, a new Early Ordovician site in the Montagne Noire in southern France. During the Early Ordovician, this region was an open marine environment located in the southern hemisphere at high polar latitudes, on the margin of the Gondwana supercontinent.
Artistic reconstruction of Cabrière Biota: in the foreground, Unpix (trilobites) and various ostracods including brachiopods and cryoliths (bottom left corner). Behind the trilobites are lobopods, chelicerates, cnidarians (blue), sponges (green), thin branched algae (red and green), hemichordates (purple), and some soft bodies. There are animals. Bivalve arthropods live in the water column along with graptolites. Image credit: Christian McCall, Prehistorya Art.
“Early Paleozoic sites with preserved soft tissues provide a wealth of information about the evolution of past life and improve our understanding of earlier ecosystems, but they are unevenly distributed in time and space. ,” said paleontologist Farid Saleh of the University of Lausanne and his colleagues.
“About 100 soft-tissue preserved assemblages have been recorded from the Cambrian, while about 30 are known from the Ordovician, and only a few have been discovered in early Ordovician rocks. .”
“The distribution of early Paleozoic remains is also paleogeographically biased, as approximately 97% of the biota discovered represents tropical and temperate ecosystems within 65 degrees north and south of the paleoequator.”
“This pattern is especially true for the Ordovician, where very few sites are known to have polar environments.”
“Among the most famous Ordovician sites, Sumchere in South Africa, Big Hill in the United States, and Winneshiek exhibit tropical ecosystems.”
“Given the rarity of Ordovician sites and their lopsided paleogeographical distribution, discovering new biota with preserved soft tissues across the aforementioned paleogeographic zones and environments will deepen our understanding of this period and This is crucial for gaining better insight into the factors driving increases in animal diversity on Earth. ”
Biomineralized species of the Cabriere biota: (a) Trilobites of the genus Unpix(b) gastropods with tubular structures, probably conuraids Sphenothalas(c) biomineralized canine cnidarians; (d) Arthrobrachiopod attached to a spongiosa, probably of the leptomid family. (e) Assemblage formed by an articulated brachiopod (center), a flattened carapace of a probably bivalve arthropod (left and right of center), and the skull of a calimenin trilobite (left). (f) Possibly visceral cyst. Scale bars – (a) and (e) 4 mm, (b) and (d) 1 cm, (c) 5 mm, (f) 2 mm.Image credit: Saleh other., doi: 10.1038/s41559-024-02331-w.
In a new paper, paleontologists describe a group of 470-million-year-old (early Ordovician) fossils, named Cabrière Biota, discovered in southern France's Montagne Noire.
The fossil site was discovered by two French amateurs, Eric Montseret and Sylvie Montseret Goujon.
Saleh and his co-authors examined about 400 extremely well-preserved soft tissue fossils taken from the site.
Fossils typically exhibit shades of brown, red, or orange and are embedded within a siliciclastic matrix of mudstone and siltstone, and their colors range from blue to green to yellow.
The Cabriere biota is characterized by a prevalence of sponges and branched algae, which constitute 26% of all identified fossils.
Also included are molluscs (14%), trilobites (12%), brachiopods (9%), cystoliths (7%), and cnidarians (6%).
An interesting feature of this biota is its rarity, with echinoderms being represented by only three specimens.
The Cabrières biota also exhibits the shells of various bivalve arthropods, which constitute 16% of the fossils identified.
Some wormlike organisms are also present in the biota (approximately 1% of identified fossils).
“The Cabrière biota was once located in close proximity to Antarctica and reveals the composition of the southernmost Ordovician ecosystem,” Dr Saleh said.
“The high biodiversity of this site suggests that the area served as a refuge for species fleeing the high temperatures that were prevalent further north at the time.”
“During this period of global warming, animals were certainly living in high-latitude refuges, escaping the extreme temperatures at the equator.”
Dr Jonathan Antcliffe, a paleontologist at the University of Lausanne, said: “The distant past gives us a glimpse of the near future that could happen to us.''
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F. Saleh other. Cabrières Biota (France) provides insight into Ordovician polar ecosystems. Nat Ecole Evol, published online on February 9, 2024. doi: 10.1038/s41559-024-02331-w
Source: www.sci.news
