Page "Targum" Paragraph 16

The Talmud explicitly states that no official targumim were composed besides these two on Torah and Nevi ' im alone, and that there is no official targum to Ketuvim (" The Writings ").

An official targum was in fact unnecessary for Ketuvim because its books played no fixed liturgical role.

The Talmud ( Megilah 3a ) states  The Targum of the Pentateuch was composed by Onkelos the proselyte under the from the mouths of R. Eleazar and R. Joshua.

The Targum of the Prophets was composed by Jonathan ben Uzziel under the guidance of Haggai, Zechariah and Malachi ( Jonathan b. Uzziel was a disciple of Hillel, so he had traditions handed down from them-Maharsha ), and the land of Israel quaked over an area of four hundred parasangs by four hundred parasangs, and a Bath Kol ( heavenly voice ) came forth and exclaimed, Who is this that has revealed My secrets to mankind?

Jonathan b. Uzziel thereupon arose and said, It is I who have revealed Thy secrets to mankind.

It is fully known to Thee that I have not done this for my own honour or for the honour of my father's house, but for Thy honour l have done it, that dissension may not increase in Israel.

He further sought to reveal a targum inner meaning of the Hagiographa, but a Bath Kol went forth and said, Enough!

What was the reason?

Because the date of the Messiah is foretold in it ".

 But did Onkelos the proselyte compose the targum to the Pentateuch?

Has not R. Ika said, in the name of R. Hananel who had it from Rab: What is meant by the text , Neh.

VIII, 8 " And they read in the book, in the law of God, with an interpretation.

and they gave the sense, and caused them to understand the reading?

And they read in the book, in the law of God: this indicates the text ; with an interpretation: this indicates the targum ,..." ( which shows that the targum dates back to the time of Ezra ).