From Lexicanum

Which source says that they were from the Second Founding? They are not listed in the Apocrypha of Davio (Codex: Space Marines (3rd Edition) p. 47, Codex: Space Marines (4th Edition) p. 8), which admittedly doesn't have all of them, but Chapter Approved 2001 p. 117 categorizes 'Original Legions', 'Second Founding', and 'Later Foundings', with the Mortifactors in the latter. "Index Astartes: Emperor's Shield" (WDUK249,US248) says they were founded in M40. —Archlords 16:57, 16 May 2007 (CEST)

The novel Warriors of Ultramar page 18: "Split from the Ultramarines during the Second Founding, nearly ten thousand years ago...". Games Workshop is rather infamous for constantly giving information which contradicts each other. Irulan 14:49, 17 May 2007 (CEST)