The Indian rupee tumbled by 57 paise to 48 Rupees 90 paise against the US dollar in early trade on Thursday, on persistent dollar demand from banks and importers, amid strengthening of the American currency overseas and a sharp fall in the domestic equity market.In the previous session on Wednesday, the rupee fell by 28 paise to close at a fresh two-year low of 48.33 rupees against the US currency. The domestic currency moved in a range between 48.68 and 48.90 rupees in morning deals today.