Fossils - A recent study by the Geological Society of America shows that Spiti houses various unique and rare fossils of marine life (Trilobites, of the Palaeozoic Era are some of the earliest legged creatures, relatives of crabs, centipedes and spiders). Portions of the Pin valley national Park lie in the Parahio Valley which is also regarded as the most fossilforous region in the world, dating back to over a billion years.
Ichnofossil assemblage recorded from the Spiti region suggests that the availability of nutrients strongly influenced their distribution, as well as abundance. The assemblage was also influenced by the presence of oxygen in both water columns as well as in unconsolidated sediments.
The typical Cambrian - Precambrian boundary marker, Trichophycus pedum has been recorded from the Kunzam La, Pin and Parahio sections. The Parahio formation of the Parahio valley in the Spiti region, in the Tethyan Himalaya of India is the best biostratigraphically resolved section of Cambrian strata in the entire Himalaya.