Complex sentence: Oesch and his colleagues at Yale and the University of California Santa Cruz announced the find, which was named EGS-zs8-1, in May 2015 passing the previous record for oldest galaxy by about 30 million years.
Split into simpler sentences: Oesch and his colleagues at Yale and the University of California Santa Cruz announced the find, which was named EGS-zs8-1, in May 2015. It beat the previous record for oldest galaxy by about 30 million years.