I may be wrong but isn't the style and words used in the book Daniel an indication that parts of the book were written by writers of differnt periods?
The integrity of Daniel has been a subject of discussion for some time. It sure looks composite, being written in two different languages, and consisting of strictly narrative portions and other apocalyptic portions. But the linguistic cleavage does not correspond to the division by genre, and it is not clear how 2:4b to ch. 6 would be intelligible without 1:1-2:4a, while ch. 7 seems to be so connected with both ch. 2 and ch. 8-12 that it seems difficult to even split the Hebrew and Aramaic portions to different authors. I am still tempted to view 2:4b to ch. 6 as an older (say, 300-200 BC) Aramaic pseudegraph that was worked over by a later prophet. For instance, the story of Nebuchadnezzer's madness in ch. 4 is clearly related to the Prayer of Nabonidus (200 BC, and originally written around 400-300 BC) discovered in the Dead Sea Scrolls (i.e. 4Q242), and a comparison of the two stories indicates that the Nebuchadnezzer story is literarily dependent on the earlier Nabonidus story (which preserves some authentic historical details, including the king's residence in Teima, Arabia), and not vice versa. The Septuagint version of Daniel also has additional narratives tacked on at the end (ch. 13-14) which are missing in the Hebrew version; the text, like that of Esther, must have existed in different recensions in the Hebrew/Aramaic and Greek. Finally, the Dead Sea Scrolls contain additional visions of the prophet Daniel, including the Vision of Daniel in 4Q243-245, and possibly the Vision of the Four Trees in 4Q552-553 (thought to date to the first century BC).