To the above we have a good parallel in the Book of Daniel; for the variations of its two chief Greek Versions - that of the Septuagint and of Theodotion - go back to variations in the Semitic.
The accounts given of Theodotion are somewhat conflicting.
In the case of the book of Daniel, as we learn from Jerome (praefatio in Dan.), the translation of Theodotion was definitely adopted by the Church, and is accordingly found in the place of the original Septuagint in all MSS.
The most probable explanation of this phenomenon is that these renderings are derived from an early Greek translation, differing from the Septuagint proper, but closely allied to that which Theodotion used as the basis of his revision.
P. 324) argues very plausibly for his priority to Aquila on the grounds, (1) that Irenaeus mentions him before Aquila, and (2) that, after Aquila's version had boen adopted by the Greek Jews, a work such as that of Theodotion would have been somewhat superfluous.
As in the case of Aquila, our knowledge of the works of Theodotion and Symmachus is practically limited to the fragments that have been preserved through the labours of Origen.
In the Septuagint column he drew attention to those passages for which there was no Hebrew equivalent by prefixing an obelus; but where the Septuagint had nothing corresponding to the Hebrew text he supplied the omissions, chiefly but not entirely from the translation of Theodotion, placing an asterisk at the beginning of the interpolation; the close of the passage to which the obelus or the asterisk was prefixed was denoted by the metobelus.
This addition was placed by Theodotion before chap. i., and Bel and the Dragon at its close, whereas by the Septuagint and the Vulgate it was reckoned as chap. xiii.