Discover France and Explore the Fossils & Geodiversity of the Sansan Paleosite in Gascony
- Wayne Munday
- 10 minutes ago
- 5 min read
Sip back and discover France and explore the fossils and geodiversity of the Sansan Paleosite. Unassumingly located in the rolling hills of Gascony in south west France near Auch this is one of Europe’s most significant Middle Miocene fossil sites open to the public. Dating to the MN6 Mammal Neogene Zone roughly 13.7–12.75 million years ago during the Serravallian Stage. First explored by Édouard Lartet, Sansan preserves an ancient subtropical wetland and woodland ecosystem that supported an exceptional biodiversity of early primates like Pliopithecus antiquus, proboscideans such as Archaeobelodon, carnivores like Amphicyon major as well as bird and mustelid species. The fossil site’s fine-grained clays, marls and the overlying “Calcaire de Sansan” tells a story of deposition in a marshy lakes environment influenced by flooding rivers that transported and gently buried animal remains to ensure exceptional fossil preservation. Situated within a landscape shaped by tectonic uplift from the Alpine–Carpathian–Dinarides Mountains, Sansan also provides evidence of climatic shifts following the Middle Miocene Climatic Optimum to cooler and more seasonal conditions.
Located in the rolling hills of the Gers at the heart of Gascony in south west France the Sansan Paleosite is one of the most compelling fossil destinations for the Middle Miocene in Europe. Located just south of Auch on the slopes of Campané this landscape combines deep time with the rural charm of Occitanie. The wider Gers basin, shaped by long-term erosion at the foot of the mountains, has long been recognised as a major fossil region. Early finds by monks such as the “turquoises of Simorre” a fossilised ivory known as odontolite was later revealed to be fossilised mastodon teeth drew scientific interest and paved the way for Lartet’s later discoveries. The region’s global significance was further elevated by the 1988 discovery of the Montréal-du-Gers site a fossil bed preserving more than 20,000 bones from around 90 species.
Gascony is a distinctive wine region in southwestern France defined by a mosaic of AOC appellations and the widely recognised Côtes de Gascogne IGP. The region also produces Armagnac, France’s oldest brandy, and Floc de Gascogne, a traditional mistelle. Gascony’s wines have three geomorphic sub-regions in Bas-Armagnac, Ténarèze and Haut-Armagnac whose “tawny sand” and clay-limestone soils determine the vigour and wine style produced by each vineyard. Bas-Armagnac’s sandy matrices favour expressive, balanced whites, while Ténarèze and Haut-Armagnac’s clay-limestone promote deeper roots and fuller-bodied reds. These soil contrasts, combined with a temperate climate and historical resilience making the region a compelling destination to visit.
The Sansan Paleosite sits upon Campané Hill near the village of Sansan and offers the visitor a free, year-round introduction to Miocene palaeontology by undertaking a 3 Km self-guided trail that begins at the village church and explores Middle Miocene deposits, ancient lake environments, and the areas key vertebrate fossils. Its fossil assemblages has revealed more than 900 species of mammals, reptiles, birds, invertebrates, and plants. The site is a registered part of France's National Inventory of Geological Heritage (Inventaire national du Patrimoine Géologique) due to its international scientific importance.
The story of Sansan begins in 1834 when Édouard Lartet who trained initially as a lawyer but was driven by a passion for natural history made his first discoveries. Lartet quickly abandoned law for palaeontology and would later become a Professor at the National Museum of Natural History in Paris where his field work and discoveries at Sansan contributed towards the emerging science of vertebrate paleontology. Among those fossil finds in 1837 was the jaw of Pliopithecus antiquus an extinct species of ape that would start to shape the development of evolutionary theory long before Darwin published On the Origin of Species in late 1859.
The discovery of Pliopithecus antiquus by Édouard Lartet became a landmark moment in nineteenth-century science, directly challenging creationist “fixist” beliefs that species were divinely created in their present and unchanging forms. Rooted in literal interpretations of biblical scripture and championed by influential naturalists such as Linnaeus and Georges Cuvier, fixism maintained that life’s diversity had remained static since creation. Lartet’s identification of the first large fossil ape known to science overturned this assumption at a time when many insisted that no extinct primates related to modern apes or humans could exist in the geological record. By revealing a Miocene primate with clear anatomical significance, Lartet provided critical evidence for the deep evolutionary history of primates and helped give emerging evolutionary thought new scientific legitimacy.
The discovery of a Miocene ape with clear anatomical connections to modern primates demonstrated that primate lineages possessed deep and dynamic evolutionary histories, challenging the long-held belief that species were fixed and unchanging. This landmark fossil provided strong evidence supporting the evolutionary theories of Étienne and Isidore Geoffroy Saint-Hilaire, suggesting that fossil humans could eventually be found, and showing that apes, like other mammals, had diversified and gone extinct over time. Lartet’s research played a pivotal role in advancing an evidence-based understanding of human origins. As Isidore Geoffroy Saint-Hilaire observed, the Sansan fossil heralded “a new era in human knowledge,” firmly establishing the Gers region’s importance in the early development of paleoanthropology.
Following the landmark discovery of the Miocene ape Pliopithecus antiquus, Lartet unearthed a nearly complete skeleton of Archaeobelodon in 1852, a relative of the mastodon that became the first mounted mastodon skeleton in Europe. The Sansan fossil assemblage further includes the formidable “bear-dog” Amphicyon major, the rhinocerotid Anisodon grande, and several true rhinos such as Brachypotherium brachypus and Lartetotherium sansaniense. Avian fossils, including the parrot Pararallus dispar, mustelids like Martes sansaniensis, and small deer such as Micromeryx and smaller predators like the Lynx-like Styriofelis lorteti.
The Sansan Paleosite reflects a European Middle Miocene environment and specifically the MN6 Mammal Neogene Zone dating roughly to 13.7–12.75 million years ago during the Serravallian Stage. This was a time that immediately followed the warmth of the Middle Miocene Climatic Optimum and marked a major climatic transition, with cooler temperatures, stronger seasonality, and increasing aridity across Central and Eastern Europe, while Northwest Europe remained humid under the influence of the proto–North Atlantic Current. Tectonic uplift of the Alpine–Carpathian–Dinarides mountain system reshaped regional topography, altered atmospheric circulation, and contributed to the fragmentation of the Paratethys Sea into a dynamic archipelago reminiscent of a prehistoric Caribbean.
The Sansan Paleosite preserves a subtropical wetland where extensive woodlands, forest patches and open areas supported exceptional biodiversity within the archipelago. Its stratigraphy comprises fine-grained clays and marls capped by the distinctive “Calcaire de Sansan” indicating that deposition was in a marshy lake environment influenced by a larger river prone to episodic flooding that transported and repeatedly trapped and buried animal carcasses.
The calm waters of the Sansan Paleosite allowed bones to settle avoiding breakage or displacement, subsequent compaction and diagenesis cemented the sediments, preserving the fossils in exceptional detail. Many of these specimens are now exhibited at the Museum of Paleontology and Comparative Anatomy in Paris. Today, the Sansan Paleosite offers visitors a unique opportunity to explore the same landscape that captivated Édouard Lartet nearly two centuries ago. Through modern interpretive displays and an immersive self-guided trail, the ancient Miocene ecosystem comes alive, revealing a world where carnivores, herbivores, primates, rodents, and large proboscideans coexisted in a dynamic and biodiverse environment.
