Discover France and Explore the Fossils and Geodiversity of Causses du Quercy in Occitanie
- Wayne Munday
- Oct 28
- 6 min read
Sip back and discover France and explore the Causses du Quercy located in south western France within the Lot and Tarn-et-Garonne departments between the Aquitaine Basin and the Massif Central covering 1,800 square kilometers of protected limestone plateaus formed during the Jurassic Period beneath a warm tropical sea. At its heart is the Causses du Quercy UNESCO Global Geopark. Over millions of years, tectonic uplift during the Alpine orogeny and subsequent karstic erosion sculpted cliffs, sinkholes, caves and underground rivers of crystal clear water to create a landscape that not only captivates visitors but also preserves an extraordinary fossil record. The Quercy Phosphorites Formation exposed at sites such as Pech Crabit, La Borie, Lavergne, Cloup d’Aural and many others documents vertebrate life from the late Eocene through to the Oligocene capturing critical events such as the Eocene–Oligocene Transition and the Grande Coupure. Fossils from small rodents, bats and primates to cat-like carnivores like Quercylurus major and early ruminants such as Mosaicomeryx quercyi tell a story of extinction and recovery. Exceptional phosphate-rich preservation even retains soft tissues and three-dimensional structures exemplified by Phosphotriton sigei a Salamander nicknamed the "Mummy". The Cloup d’Aural Phosphate Quarry now serves as a museum and research hub enabling visitors and scientists alike to explore the significance of this globally important Paleogene fossil landscape.
Causses du Quercy is located in south west of France within the Lot Department of the Occitanie region covering 1,800 square kilometers of protected countryside between the Aquitaine Basin and the Massif Central. Causses du Quercy forms vast karst plateaus of limestone called “Causses” shaped by millions of years of erosion. This landscape is characterised by steep cliffs, sinkholes, underground rivers, caves and crystal-clear springs revealing one of France’s most distinctive karst landscapes. At its heart are the Causse de Limogne, Causse de Saint-Chels and Causse de Gramat making up the Parc Naturel Régional des Causses du Quercy recognised as a UNESCO Global Geopark since 2017. Amidst the karst features is a rural community of stone-built villages, shepherds’ huts known as “caselles” and ancient dry-stone walls. Causses du Quercy is easily reached from Toulouse or Cahors to explore the Geopark's geotrails or visit the Cloup d’Aural Phosphate Mines.
The limestone Causses were formed around 170 to 145 million years ago when this region lay beneath a warm and shallow tropical epicontinental sea connected to the Tethys Ocean. As the supercontinent Pangaea began to break apart and the Atlantic Ocean opened, vast marine basins developed across what is now the Aquitaine region. In these tranquil seas, corals, molluscs, foraminifera, and coccoliths flourished and encouraged the accumulation of carbonate sediments that over millions of years these sediments compacted and lithified into limestone. Its rolling limestone Causses were formed during the Jurassic Period when tectonic activity opened the Atlantic Ocean.
During the Late Cretaceous around 65 million years ago and continuing through to 2.6 million years ago the collision between the African and Eurasian tectonic plates generated compressional forces that deformed much of southern Europe. This mountain-building event known as the Alpine orogeny was responsible for forming the Alpine-Himalayan orogenic belt of the Alps, the Pyrenees and the Himalayas mountain ranges. This tectonic activity caused the uplift of sedimentary basins including the limestone of Causses du Quercy above sea level during the Campanian–Maastrichtian stages.
Over millions of years the exposed limestone has been eroded and sculpted by groundwater dissolution into a spectacular karst landscape. Among the cracks and fissures of the soluble limestone bedrock is hidden a extraordinary Konzentrat-Lagerstätte fossil record of mammals, reptiles, amphibians, birds, insects and plants in remarkable three-dimensional detail. These cracks and fissures acted as sedimentary traps for the remains of animals washed in by floods, prey carried into dens, raptor pellets, cave dweller corpses and other remains were captured in the phosphate-bearing clay sediments called the phosphatières du Quercy. This is a network of phosphatic cave and fissure fillings that together make the longest continental paleokarst sequence known anywhere.
Interestingly, the phosphatières du Quercy tells a story about the life and environment from between 52 to 19 million years ago and importantly during the Eocene–Oligocene Transition (EOT) approximately 33.9 million years ago. This event marked one of the most transformative periods in Earth’s history when the planet shifted from a warm Greenhouse climate to a cooler Icehouse state. This transition, driven by declining atmospheric CO₂ and the growth of permanent Antarctic ice sheets had a dramatic impact across Europe triggering widespread cooling, aridification and significant drops in sea level.
These environmental stresses precipitated the "Grande Coupure" or "Great Break" where nearly half of Europe’s endemic Eocene mammals including primitive ungulates or hoofed animals, carnivores and other vertebrates became extinct and vanished. New species from Asia migrated across to Europe by the temporary drying of the Turgai Strait a shallow seaway between Europe and Asia located in what is now the Turgai Depression in modern-day Kazakhstan and western Siberia. This land bridge made it possible for Asian animals to migrate into Europe where they competed with native species, triggering widespread extinctions and fundamentally reshaped Europe's mammalian ecosystems.
The Causses du Quercy has nearly 200 fossil sites of which there are 48 geosites accessible to visitors. They preserve a remarkable diversity of nearly 700 vertebrate species including around 500 mammals. The Phosphatières du Quercy is part of the Quercy Phosphorites Formation and captures fifteen successive European Mammalian Paleogene (MP) reference levels from MP 16 to 30. Each reference levels represents a distinct evolutionary phase where the ecosystem can be reconstructed according to the influence of environmental change, extinction events and faunal turnovers all of which reshaped European mammalian ecosystems during the Paleogene including the "Grande Coupure".
During the Bartonian–Priabonian stages (MP 16–18) approximately 38 – 36 million years ago the Quercy Phosphorites Formation at fossil sites such as Pech Crabit, La Borie, La Boisserie, Pech Tarn, La Grive-St-Alban and Lavergne record a thriving biodiversity of a warm forested habitat. Small mammals including primitive rodents like Theridomys varians and Burgia marandati, insectivores, early bats and small placental mammals called amphilemurids dominate these assemblages alongside arboreal primates such as Pronycticebus, Pseudoloris and Protoadapis. These mammal communities represent the last predominantly European mammals before the onset of global cooling and ecological stress that culminated in the Grande Coupure.
By MP 19–20, approximately 35–34 million years ago during the Priabonian stage of the Late Eocene and the onset of the Oligocene the Quercy fossil sites of Pech Desse, Pech du Fraysse, Itardies, and La Débruge show the final appearances of classic Eocene hoofed animals. These include Palaeotherium medium, an early horse ancestor, Anoplotherium commune, a distant relative of camels, and the extinct rhinocerotid Cadurcotherium cayluxi. The Grande Coupure, recorded at MP 21 around 33.5 million years ago at fossil localities including Sainte-Néboule and Cloup d’Aural marks a major faunal turnover with the first appearance of Asian immigrant species. These include the gliding rodent Eomys quercyi, cricetid rodents such as Eucricetodon atavus, and nimravid carnivores including the large Quercylurus major and the smaller Eofelis edwardsi described as “false sabre-tooth cats”. This pivotal event reshaped European terrestrial ecosystems representing one of the most significant mammalian turnovers of the Paleogene.
Following the Grande Coupure and during the Rupelian–Chattian stages approximately 32 – 25 million years ago, the Quercy Phosphorites Formation documents a remarkable recovery and diversification of European mammals. Key fossil sites at Lavergne, Caylux, Pech Crabit, La Bouffie, Robiac, Saint-Lizier, Sainte-Néboule, Saint-Martin-de-Castillon and Cloup d’Aural reveal the stabilisation and radiation of mammal communities. Small rodents, particularly gliriforms and cricetids such as Issiodoromys, Eucricetodon, Tarnomys and Eomys, diversified alongside early bats like Hipposideros, while large cat-like carnivores including Dinailurictis bonali and much smaller Nimravus intermedius expanded their ecological roles as predators. Among the hoofed animals, specialised basal ruminants such as Mosaicomeryx quercyi appeared adapted to the changing Oligocene environment. Together, these fossil assemblages highlight ecosystem recovery after the Grande Coupure.
Central to this exceptional preservation are phosphate-rich sediments in Quercy’s paleokarst is thought to have been enabled by rapid “flash” fossilisation to capture the delicate three-dimensional features. Mummified amphibians, intact bat skulls, soft-bodied arthropods and phosphatised seeds, fruits and flowers survive with extraordinary detail. Among the best soft-tissue preservation is a Salamander, nicknamed "Mummy" called Phosphotriton sigei whose internal organs and its last meal of a frog still remain intact.
The Cloup d’Aural Phosphate Quarry has been transformed into a public museum and interpretive center within the Causses du Quercy UNESCO Global Geopark, offering visitors an immersive opportunity to explore the region’s distinctive karst landscapes and rich fossil heritage. Beyond its educational role, the site continues to serve as a hub for fossil research, shedding light on the evolution, ecology and diversity of late Eocene vertebrates in south west France.
