Spectroscopic confirmation of an extreme starburst at redshift 4.547

We report the spectroscopic confirmation of a submillimeter galaxy (SMG) at z = 4.547 with an estimated L(IR) = (0.5-2.0) x 10(13) L(circle dot). The spectra, mid-IR, and X-ray properties indicate the bolometric luminosity is dominated by star formation at a rate of >1000 M(circle dot) yr(-1). Multiple, spatially separated components are visible in the Ly alpha line with an observed velocity difference of up to 380 km s(-1) and the object morphology indicates a merger. The best-fit spectral energy distribution and spectral line indicators suggest the object is 2-8 Myr old and contains >10(10) M(circle dot) of stellar mass. This object is a likely progenitor for the massive early-type systems seen at. z similar to 2.