Ratan Kar

Oldest known non-marine diatoms (Aulacoseira) from the uppermost Cretaceous Deccan Intertrappean beds and Lameta Formation of India

Non-marine diatoms occur in the Deccan Intertrappean beds (Upper Cretaceous) of Mohgaon-Kalan, Chhindwara District, Madhya Pradesh and Pisdura, Lameta Formation (Upper Cretaceous), Maharashtra, India. This represents the oldest record of non-marine diatoms yet reported and the oldest from the Indian subcontinent. The diatoms were recovered from thin sections of chert and dinosaur coprolites by random fracturing. Solitary forms are the most common but colonial filaments up to five cells were also observed. Based on the morphological characters, the diatoms are identified as Aulacoseira Thwaites. The Lower Cretaceous marine diatom genus Archepyrgus Gersonde and Harwood also resembles Aulacoseira in general morphological characters and it seems that Aulacoseira evolved from Archepyrgus and migrated to the non-marine realm.

Modern pollen deposition in glacial settings in the Himalaya (India): abundance of Pinus pollen and its significance

abstract Thirty-five surface sediment samples from three glacial sites – [Chorabari Glacier (Kedarnath), Hamtah and Chhatru glaciers (Lahaul-Spiti)] – situated in the western Himalaya, India, were palynologically analysed to explore the relationship between the modern pollen assemblages and the extant vegetation. The Chorabari Glacier is located in the Greater Himalaya and influenced by the Southwest Summer Monsoon; whereas the Hamtah and Chhatru glaciers are located in the Trans-Himalaya and affected more by the Western Disturbances (winter precipitation). The area around Chorabari Glacier receives abundant rainfall, while the Hamtah and Chhatru glaciers are in a high-altitude cold desert. Palynological studies have revealed an overwhelming dominance of Pinus pollen in all the samples. Though the sampling sites are 2 to 8 km away from the treeline and characterised by herbaceous ground vegetation, the marked predominance of arboreal pollen (especially Pinus) in the sediments stresses the importance of a proper interpretation of modern pollen data, so as to have an appropriate standard for deciphering the pollen–vegetation relationship in the respective study areas.