Spectral evolution of iPTF13bvn in the wavelength range 4000−8000 Å (top panel). Comparison of the visible spectra of iPTF13bvn to those of other SNe Ib at approximately 35 d past the explosion (bottom panel). Thick dashed lines mark the central wavelength of the marked emission lines at rest. Thin dashed lines mark the absorption minima associated with the emission lines derived from Gaussian fits to the absorption features. The spectra up to 16 d past the explosion have been selected from the early spectral sequence presented by Cao et al. (2013).