Reconstruction of Upper Siwalik palaeoecology and palaeoclimatology using microfossil palaeocommunities

摘要: Upper Siwalik sediments, exposed in the vicinity of Chandigarh, have yielded microvertebrates addition to large vertebrates, invertebrates (molluscs, ostracods and decapods), charophytes, pollen spores. These assemblages derive from at least four horizons Tatrot Pinjor Formations (spanning period between V4 1.8 Ma). Among microvertebrates, a diverse assemblage micromammals, including rodents, insectivores lagomorphs, has been recovered these deposits. accumulations found be primarily scatological origin. The most common microfossil communities belonged pond, pond bank, wooded grassland, sandy plain, bushland temperate montane habitats. Presence gerbil rodents such as Tatera associated with lizards (e.g. Uromastyx, Calotes scincid) some deposits might indicate semi-arid conditions or intermittent dry periods. replacement survival-oriented cricetids by reproduction-oriented murid Late Miocene is indicative inter-annual seasonal variations (intensification monsoons). Across Mio^Pliocene boundary change dietary habits among also observed. Mid-Miocene nongrazers Antemus Progonomys gave way (Parapelomys Karnimata) Pliocene forms (Dilatomys, Bandicota, Nesokia, Hadromys, Golunda), which were predominantly grazers. An increase body size inferred their first upper molars. Within Pliocene, across Tatrot^Pinjor (around 2.5 Ma), significant generic level, leading appearance modern Rhizomys, Tatera, This (V2.5 Ma) marked great diversification species, probably indicating an intensification monsoons. interpretation further strengthened occurrence palynological reflecting alternately wet conditions. 7 2003 Elsevier Science B.V. All rights reserved.