Monte San Giorgio
Since 2003 • Natural
The pyramid-shaped, wooded mountain of Monte San Giorgio beside Lake Lugano is regarded as the best fossil record of marine life from the Triassic Period (245–230 million years ago). The sequence records life in a tropical lagoon environment, sheltered and partially separated from the open sea by an offshore reef. Diverse marine life flourished within this lagoon, including reptiles, fish, bivalves, ammonites, echinoderms and crustaceans. Because the lagoon was near land, the remains also include land-based fossils of reptiles, insects and plants, resulting in an extremely rich source of fossils.
Monte San Giorgio is a pyramid-shaped, wooded mountain, which lies south of Lake Lugano in Ticino Canton. The site contains internationally important fossil remains from the Middle Triassic period. San Giorgio lies within an area identified as a Landscape Protection Zone under Swiss law.
The Mid Triassic rock succession rests on older, Permian volcanic rocks exposed on the north face of Monte San Giorgio. The Mid Triassic sequence consists of approximately 1,000 m of reef limestones, dolomites and bituminous shales which formed in marine conditions on the margins of the Triassic 'Tethys' Ocean. The exceptional fossil interest within the sequence arises because of the presence of five distinct, fossiliferous formations, the 'Grenzbitumenzone', the Cava Inferiore, Cava Superiore, Cassina Beds and the 'Kalkschieferzone'. The sequence records life in a tropical lagoon environment, sheltered and partially separated from the open sea by an offshore reef. A diversity of marine life flourished within this lagoon, including reptiles, fish, bivalves, ammonites, echinoderms and crustaceans. A stagnant and undisturbed seabed provided ideal conditions for the preservation of these animals, when they died and fell to the sea floor. Today, fossils are abundant and exceptionally detailed. Because the lagoon was near to land, the fossil remains also include some land-based fossils including reptiles, insects and plants. The fossiliferous rock succession is exposed in Switzerland on Monte San Giorgio as well as in the immediately adjacent area of Italy, in the area around Besano. Fossils from the mountain have been known to science for over 150 years. The vertebrate material includes particularly spectacular specimens, including large, articulated skeletons up to 6 m in length. Complete skeletons include ichthyosaurs, nothosaurs, placodonts, and the remarkable 'giraffe-necked' saurian, Tanystropheus. The land-based fauna is more restricted, but includes a significant and unique complete skeleton of the archosaur, Ticinosuchus, the first complete skeleton from this group to be discovered in the northern hemisphere.
Although it is primarily of geological significance, Monte San Giorgio also displays other natural values, as well as cultural links between the geology and the life of the local community. Noteworthy features include dry meadows on limestone subsoils that are home to plant populations not found elsewhere in Switzerland or in the entire southern Alpine zone of Italy. The site is rich in fungi and has 37 of the modern vertebrate species on the national Red List, 21 of which are protected under the Berne Convention.
Monte San Giorgio is unique in the world as the best single fossil record of Triassic marine life. The strict, systematic and continuous scientific research that has been carried out for over 75 years in Switzerland and Italy, almost exclusively by the universities of Zurich and Milan, have resulted in a remarkably complete and coordinated record of the site.
The site is in the ownership of three different local communes. Around 10% is cultivated, privately owned land, mostly near Meride and Riva San Vitale. The presence of five distinct fossiliferous levels provides the opportunity for comparative and evolutionary studies through time.
Other significant Triassic fossil sites of equivalent international importance provide evidence of terrestrial, rather than marine life.
The quantity and quality of fossil biota enables interpretation of species evolution, palaeo-environments and land-forming processes that existed 200 million years ago. The site provides a record of marine life during a critical period in vertebrate evolution on Earth, and has an importance that extends beyond representation of life in the Triassic 'Tethys' Ocean, to provide a global reference point for comparative studies of evolution.
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