New fossil site of worldwide importance uncovered in southern France - UNIL L'ACTU
Artistic reconstruction of the Cabrières Biota.
Credit: Christian McCall (Prehistorica Art).
Today, it's the turn of palaeontologists from the Faculty of Geosciences and Environment at the University of Lausanne (UNIL), Switzerland, who, together with international colleagues, have just announced the discovery of a large collection of exceptionally well preserved fossils in the Lower Ordovician formation at Montagne Noire, in the Hérault department of France. The Lower Ordovician deposits were formed between about 485.4 and 470 million years before creationists believe Earth was magicked out of nothing.
Tell me all about the Lower Ordovician period particularly in the Montagne Noire, in the Hérault department of France, including how its age was determined. The Lower Ordovician period is a significant geological epoch characterized by a diversification of marine life, particularly marine invertebrates such as trilobites, brachiopods, and mollusks. It spans from approximately 485.4 to 470 million years ago. The Lower Ordovician is part of the larger Ordovician period, which is divided into three stages: Tremadocian, Floian, and Dapingian.Apart from the exceptional preservation of the fossils, the significance of this find is that when the Lower Ordovician deposits were forming, what is now southern France was located close to the South Pole, so the biota tells us a great deal about the climate and ecosystem at the South Pole 470 million years ago. The palaeontologisst have just published their findings, open access, in the journal Nature Ecology & Evolution. Their work is also described in a news release from the University of Lausanne:
Montagne Noire, located in the Hérault department of France, is a region renowned for its Lower Ordovician sedimentary rocks, which provide valuable insights into the Earth's geological history during this period. The geological formations in Montagne Noire contain a wealth of fossils and sedimentary structures that have been studied extensively by geologists and paleontologists.
Determining the age of rocks and geological formations is crucial for understanding Earth's history. In the case of the Lower Ordovician rocks in Montagne Noire, their age has been determined through various methods, including biostratigraphy and radiometric dating.
Through a combination of these methods, geologists have been able to establish the age of the Lower Ordovician rocks in Montagne Noire and gain insights into the geological processes and environmental conditions that prevailed during this period. This research contributes to our understanding of Earth's history and the evolution of life on our planet.
- Biostratigraphy: This method relies on the identification and correlation of fossil assemblages found within rock layers. Certain species of organisms existed only during specific periods of Earth's history, making them useful markers for dating rocks. By studying the fossil content of the Lower Ordovician rocks in Montagne Noire and comparing them to well-established fossil sequences from other regions, geologists can determine the relative age of the rocks.
- Radiometric dating: Radiometric dating techniques, such as uranium-lead dating or potassium-argon dating, can provide absolute ages for rocks by measuring the decay of radioactive isotopes within them. Although not all rocks are amenable to radiometric dating, certain minerals within sedimentary rocks can be dated using isotopic methods. By analyzing the age of specific minerals or volcanic layers within the Lower Ordovician formations in Montagne Noire, geologists can obtain precise numerical ages for these rocks.
Nearly 400 exceptionally well-preserved fossils dating back 470 million years have been discovered in the south of France by two amateur paleontologists. This new fossil site of worldwide importance has been analyzed by scientists from the University of Lausanne, in collaboration with the CNRS and international teams. This extraordinary discovery provides unprecedented information on the polar ecosystems of the Ordovician period.Technical details of the fossils and the background to their research is given in the team's paper in Nature Ecology & Evolution:
Paleontology enthusiasts have unearthed one of the world's richest and most diverse fossil sites from the Lower Ordovician period (around 470 million years ago). Located in Montagne Noire, in the Hérault department of France, this deposit of over 400 fossils is distinguished by an exceptionally well-preserved fauna. In addition to shelly components, it contains extremely rare soft elements, such as digestive systems and cuticles, in a remarkable state of preservation. Moreover, this biota was once located very close to the South Pole, revealing the composition of Ordovician southernmost ecosystems.
At the Faculty of Geosciences and Environment at the University of Lausanne (UNIL), scientists have collaborated with the CNRS (CNRS PR) and international teams to carry out the first analyses of this deposit, known as the Cabrières biota. The results are published in Nature Ecology & Evolution.
Ordovician climate refugia
Analyses of the new biota reveal the presence of arthropods (a group that includes millipedes and shrimps) and cnidarians (a group that includes jellyfish and corals), as well as a large number of algae and sponges. The site's high biodiversity suggests that this area served as a refuge for species that had escaped the high temperatures prevailing further north at the time.
"At this time of intense global warming, animals were indeed living in high latitude refugia, escaping extreme equatorial temperatures," points out Farid Saleh, researcher at the University of Lausanne, and first author of the study. "The distant past gives us a glimpse of our possible near future," adds Jonathan Antcliffe, researcher at the University of Lausanne and co-author of the study.
For their part, Eric Monceret and Sylvie Monceret-Goujon, the amateurs who discovered the site, add with enthusiasm: "We've been prospecting and searching for fossils since the age of twenty," says Eric Monceret. "When we came across this amazing biota, we understood the importance of the discovery and went from amazement to excitement," adds Sylvie Monceret-Goujon.
This first publication marks the start of a long research program involving large-scale excavations and in-depth fossil analyses. Using innovative methods and techniques, the aim is to reveal the internal and external anatomy of the organisms, as well as to deduce their phylogenetic relationships and modes of life.
Eric and Slyvie Monceret, who discovered the biota.Photo credit: Eric and Sylvie Monceret
Mollusc from the Cabrières Biota.Credit: Farid Saleh - UNIL
Lobopod from the Cabrières Biota.Credit: Farid Saleh - UNIL
AbstractThe compelling evidence is then, that in that long period of Earth's 'pre-Creation Week' history, 470 million years ago, multicellular life had evolved and diversified into the Cabrières Biota and was leaving fossilised remains in marine sediment being laid down in what is now part of southern France but which was then located near the south pole, from where plate tectonics was to move it to its present position.
Early Palaeozoic sites with soft-tissue preservation are predominantly found in Cambrian rocks and tend to capture past tropical and temperate ecosystems. In this study, we describe the diversity and preservation of the Cabrières Biota, a newly discovered Early Ordovician Lagerstätte from Montagne Noire, southern France. The Cabrières Biota showcases a diverse polar assemblage of both biomineralized and soft-bodied organisms predominantly preserved in iron oxides. Echinoderms are extremely scarce, while sponges and algae are abundantly represented. Non-biomineralized arthropod fragments are also preserved, along with faunal elements reminiscent of Cambrian Burgess Shale-type ecosystems, such as armoured lobopodians. The taxonomic diversity observed in the Cabrières Biota mixes Early Ordovician Lagerstätten taxa with Cambrian forms. By potentially being the closest Lagerstätte to the South Pole, the Cabrières Biota probably served as a biotic refuge amid the high-water temperatures of the Early Ordovician, and shows comparable ecological structuring to modern polar communities.
Main
Early Palaeozoic sites with soft-tissue preservation1 provide a wealth of information on the evolution of past life and enhance our understanding of previous ecosystems2,3, but are unequally distributed in time and space. While approximately 100 assemblages with soft-tissue preservation4 have been described from the Cambrian, around 30 are known from the Ordovician5,6,7,8,9,10,11,12,13,14,15,16,17, and only a few Lagerstätten are discovered in Early Ordovician rocks4.
The distribution of Early Palaeozoic Lagerstätten is also palaeogeographically skewed, as approximately 97% of discovered biotas represent tropical and temperate ecosystems within 65° north and south of the palaeoequator4. This pattern is particularly true for the Ordovician, where very few Lagerstätten are known from polar environments4. Among the most famous Ordovician Lagerstätten, the Soom Shale (Upper Ordovician, South Africa), Big Hill (Late Ordovician, United States) and Winneshiek (Middle Ordovician, United States) biotas are indicative of tropical ecosystems11,12,13 (Extended Data Fig. 1). The Liexi Fauna, along with the Fenxiang and Tonggao biotas from the Early Ordovician of China, represent tropical to warm temperate ecosystems5,6,7 (Extended Data Fig. 1). The Afon Gam (Early Ordovician, United Kingdom), Castle Bank (Middle Ordovician, United Kingdom) and Llanfawr (Middle Ordovician, United Kingdom) biotas provide valuable information on cold to temperate Ordovician communities near the polar circle8,9,10(Extended Data Fig. 1). The Early Ordovician Fezouata (Morocco) and Klabava (Czech Republic) biotas are the rare exceptions to this pattern, providing insights into strictly polar ecosystems15,16 (Extended Data Fig. 1). Taken together, all these sites exhibit a mix of typical Cambrian and later Palaeozoic taxa, and suggest that marine assemblages were in transition between two early biodiversification events, the Cambrian Explosion and the Great Ordovician Biodiversification Event18,19.
Considering the rarity of Ordovician Lagerstätten (Extended Data Fig. 1) and their skewed palaeogeographic distribution (Extended Data Fig. 1), the discovery of new biotas with soft-tissue preservation beyond the aforementioned palaeogeographic zones and environments is crucial for expanding our understanding of this time period and gaining better insights into the factors driving the rise of animal diversity on Earth. In this study, we describe a new fossil assemblage with soft-tissue preservation, the Cabrières Biota, from the Early Ordovician of southern Montagne Noire, France. The taxonomic diversity of this fossil biota is described, and the preservation of the fossils is investigated. The recent findings are then discussed in light of other Early Ordovician Lagerstätten. This newly discovered biota is of particular importance as it is a close Ordovician Lagerstätte to the contemporaneous South Pole (Extended Data Fig. 1), constituting a cornerstone for understanding ancient polar ecosystems and their evolution.Fig. 1: Biomineralized taxa of the Cabrières Biota.
a, Trilobite of the genus Ampyx (UCBL-FSL713598). b, Gastropods associated with a tube-like structure, probably the conulariid Sphenothallus (UCBL-FSL713599). c, Biomineralized conulariid cnidarian (UCBL-FSL713600). d, Articulated brachiopods attached to a possible leptomitid sponge (UCBL-FSL713601). e, Assemblage formed of articulated brachiopods (centre), flattened carapaces probably of bivalved arthropods (centre left and right) and a calymenine trilobite cranidium (left; UCBL-FSL713602). f, A hyolith with possible internal organs (UCBL-FSL713603). Scale bars represent 4 mm in a and e, 1 cm in b and d, 5 mm in c, and 2 mm in f.Fig. 2: Sponges, algae and possible hemichordates from the Cabrières Biota.
a, A large sponge from the Cabrières Biota, possibly a demosponge (UCBL-FSL713604). b, Sponge (UCBL-FSL713605). c, Same specimen showing clear differentiation between the soft tissues (pink) and the mineralized skeleton (green) under multispectral imaging. d, Thick branching algae (UCBL-FSL713606). e, Thin branching algae (UCBL-FSL713607). f, More complex algae (UCBL-FSL713608). g, Organic tube of an Oesia-like enteropneust hemichordate (=Margaretia; UCBL-FSL713609). Scale bars represent 1 cm in a and f, 5 mm in e, and 3 mm in b–d and g.Fig. 3: Non-biomineralized arthropods of the Cabrières Biota.
a, Phyllocarid carapace valves ornamented with very closely spaced, longitudinal striations and associated with abdominal segments (UCBL-FSL713609). b, Phyllocarid carapace valve with longitudinal striations preserved near a graptolite (UCBL-FSL713610). c, Possible chelicerate gnathobase (UCBL-FSL713611). d, Spiny arthropod appendage (UCBL-FSL713612). e, Segmented arthropod with chelicerate-like ornamentation and an eye (UCBL-FSL713613). f, Part of a segmented arthropod with chelicerate-like ornamentation and an appendage (UCBL-FSL713614). ap, appendage; co, chelicerate ornamentation; ey, eye; ls, longitudinal striations; sb, segmented body. Scale bars represent 2 mm in a; 8 mm in b, c and f; 5 mm in d and e; and 4 mm in j.Fig. 4: Vermiform organisms from the Cabrières Biota.
a, Unidentified vermiform organism UCBL-FSL713615, with possible remains of the gut and external ornamentation of tiny nodes. b,c, Incomplete armoured lobopodians UCBL-FSL713616 (b) and UCBL-FSL713617 (c) exhibiting two sclerite plates along an elongated soft body with annulations. A lateral extension in b possibly represents remains of the proximal part of a lobopod (?lo). d,e Close-up three-dimensional lateral (d) and top (e) views of part of UCBL-FSL713617, from the dotted box in c. Arrowheads point to lateral outgrowths associated with annulations that could represent spines or lobopod appendicules. an, annulations; gu, gut; lo, lobopod; otn, ornamentation of tiny nodes; ro, reticulate ornamentation; sp, sclerite plates. Scale bars represent 5 mm in a and c, and 1 mm in b and e; note that due to the three-dimensional rotation, no scale bar is given for d and the reader is instead invited to refer to scale bars in c and e.Fig. 5: Mode of fossil preservation.
a, Backscattered electron microscopy image revealing white iron oxide minerals and some limited black carbonaceous material within the fossils of the Cabrières Biota. b, The iron oxides appear shapeless, lacking distinct framboids or euhedral minerals. c, Semi-quantitative elemental proportions from SEM–EDX analyses indicate that the fossils exhibit a higher iron content compared with their surrounding aluminosilicate matrices. d, Fe K-edge XANES spectroscopy shows that the iron present in the Montagne Noire fossils exists in the form of oxides and hydroxides. e,f, Synchrotron µXRF major-to-trace elemental mapping shows that modern weathering elements such as manganese and arsenic are deposited on the surface of the samples. Scale bars represent 100 µm in a, 50 µm in b and 5 mm in e and f.Fig. 6: Artistic reconstruction of the Cabrières Biota.
In the foreground, a row of Ampyx (trilobites) and various shelly organisms, including brachiopods and a hyolith (bottom left corner). Behind the trilobites, a lobopodian, a chelicerate, cnidarians (blue), sponges (green), thin branching algae (red and green) and hemichordate tubes (purple), along with some molluscs. Bivalved arthropods inhabit the water column along with graptolites.Credit: Christian McCall (Prehistorica Art).Extended Data Fig. 2: Geographic and stratigraphic context.
(a) Geographic position of the Cabrières Biota in the Montagne Noire in southern France, (b) within a 1 km radius around the Cabrières village. Map data ©2022 Google. The Cabrières Biota is discovered in the late Floian (Fl3) Landeyran Formation (c). (d) Photograph of the outcrop that yielded most soft-tissue preservation. (e) Geological map of the Montagne Noire showing the position of the new Lagerstätte in the southern part of the complex.Extended Data Fig. 4: Additional views of the possible leptomitid sponge UCBL-FSL713601 shown in Fig. 1d.
(a) Optical photograph under polarised light of the entire specimen. (b) Close-up view under polarised light from the box in (a) showing projected longitudinal spicules. Scale bars represent 1 cm in (a), and 5 mm in (b).Extended Data Fig. 5: Another possible leptomitid sponge, associated to the thin branching algae UCBL-FSL713607.
(a) Optical photograph under polarised light of the entire specimen. (b) Close-up view under polarised light from the box in (a) showing longitudinal skeletal elements. Scale bars represent 1 cm in (a), and 1 mm in (b).Extended Data Fig. 6: Additional views of the large sponge UCBL-FSL713604 shown in Fig. 2a.
(a) Optical photograph of the entire organism. (b) Close-up view of one side of the organism, from the box in (a). (c) Close-up view of the osculum from the box in (b). (d, e) Close-up views under polarised light showing the skeletal framework, from the corresponding boxes in (c). Scale bars represent 1 cm in (a) and (b), 5 mm in (c), and 1 mm in (d) and (e).Extended Data Fig. 7: Additional views of the algae shown in Fig. 2.
(a) Optical photograph of the thick branching algae UCBL-FSL713606 shown in Fig. 2d. (b) Close-up view under polarised light of basal branches, from the box in (a). (c) Optical photograph under polarised light of the thin branching algae UCBL-FSL713607 shown in Fig. 2e. (d) Close-up view under polarised light from the box in (c) highlighting textural differences between algae (right) and sponges (left). (e) Optical photograph under low angle and polarised light of the more complex algae UCBL-FSL713608 shown in Fig. 2f. (f) Close-up view under polarised light from the box in (e) highlighting branched clumps of flat kidney-shaped segments. Scale bars represent 5 cm in (a), (b), (c) and (f), 1 mm in (d), and 1 cm in (e).Extended Data Fig. 8: Phyllocarid crustaceans from the Cabrières Biota.
(a, b) Optical photograph (a) and interpretative line drawing (b) of the counterpart of UCBL-FSL713609 shown in Fig. 3a. The specimen contains two left valves ornamented with very closely spaced, longitudinal striations. The bottom valve (white) is associated with a few abdominal segments. Fossil remains located anteriorly to the top valve (light blue) may represent a rostral plate. (c, d) Optical photograph (c) and interpretative line drawing (d) of the left valve UCBL-FSL713610 shown in Fig. 3b. Abbreviations: al, anterodorsal lobe; as, abdominal segments; cc, cephalic carina; co, carapace ornamentation; mdp, median dorsal plate; rp, rostral plate. Scale bars represent 5 mm.Extended Data Fig. 9: Additional images and interpretative drawings of the chelicerates in Fig. 3e, f.
(a, b) Optical photograph (a) and interpretative line drawing (b) of the chelicerate UCBL-FSL713613. The presence of a prosoma lacking enlarged axial nodes on opisthosomal tergites, reduced genal spines, and an opisthosoma that is largest at the third and fourth tergite, likely suggest chasmataspid affinities. (c) Close up of the eye and the ornamentation. (d–g) Optical photographs under polarised light of the part (d) and the counterpart (f), and corresponding interpretative line drawings (e, g) of the chelicerate UCBL-FSL713614. Green highlights ventral features. Pale purple shows dorsal features. The sample displays a carapace, three tergites, and a possible appendage. The presence of a possible metastoma suggest non-arachnid dekatriatan affinities. (h, i) Close-up photographs showing the ornamentation. Abbreviations: appendage (ap); (ax) axis; cardiac lobe (cdl); doublure (db); ornamentation (or); eye (ey); metastoma (m); and tergite (t). Scale bars represent 2 mm in (c)s and (i), 3 mm in (h), 5 mm in (a) and (b), and 8 mm in (d), (e), (f), and (g).Extended Data Fig. 10: Synchrotron-based X-ray fluorescence major-to-elemental mapping of the Cabrières Biota.
(a) Optical photograph under polarised light of the assemblage UCBL-FSL713602 shown in Fig. 1e. (b, c) False-colour overlays of manganese (red), iron (green) and potassium (blue) (b), and arsenic (red), iron (green) and potassium (blue) (c) distributions from the box in (a). Acquisition parameters: 200 μm steps, 80 ms dwell time, 51,100 pixels. (d) Optical photograph under polarised light of sponge UCBL-FSL713618. (e) Close-up view from the box in (d). (f, g) False-colour overlays of manganese (red), iron (green) and potassium (blue) distributions from the corresponding boxes in (e) and (f). Acquisition parameters: 200 μm steps, 60 ms dwell time, 6,150 pixels in (f); 100 μm steps, 60 ms dwell time, 4,800 pixels in (g). The white circle in (g) locates the XANES analysis shown in Fig. 4d. (h) Average µXRF spectra and main elemental contributions from the corresponding numbered boxes in c (156 pixels) and f (208 pixels). Scale bars represent 1 cm in (a), (b), (c) and (d), 5 mm in (e) and (f), and 1 mm in (g).
Saleh, F., Lustri, L., Gueriau, P. et al.
The Cabrières Biota (France) provides insights into Ordovician polar ecosystems. Nat Ecol Evol (2024). https://doi.org/10.1038/s41559-024-02331-w
Copyright: © 2024 The authors.
Published by Springer Nature Ltd. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)
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