2D spectra of our sample, flux-calibrated and corrected for telluric absorption. For display purposes only, these spectra were smoothed with a 70 Å boxcar filter in wavelength and 0.7′′ FWHM Gaussian along the slit. The galaxies are sorted by decreasing K-band continuum S/N. Top: galaxies with a spectroscopic redshift z_spec > 3, aligned on the same rest frame wavelength grid. The most prominent emission and absorption lines are labeled in blue and orange ticks, respectively. Galaxies with an uncertain redshift (see text) are marked with an asterisk. Middle: same as top but for z_spec < 3. Bottom: galaxies without spectroscopic redshift, aligned on the same observed wavelength grid. The average error spectrum is shown at the top, to illustrate the regions with the strongest atmospheric features (telluric absorption and OH lines).