Arin, FYI the OU website posted some articles on the topic of what was written, by whom and when.   I posted the information on our General Judaism forum some time ago (link).

They state 

Daniel – Daniel (12 chapters) - Written by the Men of the Great Assembly circa 3450 (311 BCE);   Daniel in exile, the fiery furnace, the writing on the wall, the lion’s den, the Messianic era. Covers events from 3319-3392 (442-369 BCE)  *Daniel was a member of the Great Assembly.


סופי

And everything that Sarah tells you, listen to her voice. Bereshit (Genesis) 21:12