Could you provide actual citations of works by these authors, with standard items like book name, chapter, and verse? Thanks!
Go to http://www.earlychristianwritings.com
There you will find all of the information concerning the quotes which I gave and the information dealing with 1 Clement, chap 25 verses 1-5, which deal with "pope" Clement's belief in the mythical phoenix being a literal creature.
For more on this, I would also recommend the book, "The Lost Books of the Bible," William Hone, Rev. Jeremiah Jones, and Wiliam Wake, Archbishop of Canterbury.