Is there any manuscript or historical evidence to support the final 13 verses of Genesis 50 that appear in the Joseph Smith Translation? The Joseph Smith Translation of the Bible is unique in its listing of 13 verses at the end of the last chapter of Genesis--chapter 50.  These verses specifically name Moses, who would be born 400 years later.  They also contain a prophecy of a man named Joseph, which is believed by the LDS to be a reference to Joseph Smith, Jr, since his name, "Joseph", is "after the name of his father".


  And that seer will I bless, and they that seek to destroy him shall be confounded; for this promise I give unto you; for I will remember you from generation to generation; and his name shall be called Joseph, and it shall be after the name of his father; and he shall be like unto you; for the thing which the Lord shall bring forth by his hand shall bring my people unto salvation.  Genesis 50:33 Joseph Smith Translation


What is the manuscript evidence--that is, the evidence of ancient manuscripts in ancient languages (Hebrew, Greek, Latin, etc.)-- to support the existence of these verses in the original copies?  Is there any idea how they could have been lost?
To start with, it might be helpful to clarify the terms used here.

Manuscript Evidence

Manuscript Evidence is a term that is well defined outside of Christianity, in the field of Textual Criticism.


  Textual criticism (or lower criticism) is a branch of literary
  criticism that is concerned with the identification and removal of
  transcription errors in the texts of manuscripts. Ancient scribes made
  errors or alterations when copying manuscripts by hand. Given a
  manuscript copy, several or many copies, but not the original
  document, the textual critic seeks to reconstruct the original text
  (the archetype or autograph) as closely as possible. The same
  processes can be used to attempt to reconstruct intermediate editions,
  or recensions, of a document's transcription history. The ultimate
  objective of the textual critic's work is the production of a
  "critical edition" containing a text most closely approximating the
  original.


The basics are covered in another post on this site: What is “Manuscript Evidence” and how is it useful?, and it would be redundant cover the same ground here.  The short version is this:  


The more copies we have of a text the more confident we can be that our current translations are true to the original text.
Older copies are less likely to contain unintentional/copyist errors than newer ones, so the more old manuscripts we have, the better. 


Historical Evidence

This would be external evidence such as works written by historians of the time, or close to the time, corroborated by accepted historical evidence - documents recording the events at the time, archaeology, etc.

Answer, now that the terms have been clarified:

When it comes to the final verses of genesis, we have *no strong manuscript evidence*.  The evidence we do have is very weak, using the accepted forms of textual criticism.  It is all recent, and all stems from the translation of one author, and a translation of original brass plates that are not available to study.  We can only believe, with no external evidence, that they ever existed at all.  All that we have at this time is the translated verses.  We have no ancient copies of any texts that corroborate these verses.  All we really have is the word of the founder, and other believers within.

When it comes to historical evidence, we also have very little.  Before Joseph Smith, we have no historians referring to these verses, no Church sermons referring to them, nothing.



Of course, to the believer, lack of proof is not proof of lack.  It's impossible to prove the non-existence of something.  The answer to this question could, conceivably, be rendered null and void by the discovery of such manuscript or historical evidence.  The lack of external evidence doesn't constitute proof that the verses are invalid.  it just means that we have no corroborating evidence.  All we have is the word of Joseph Smith and a handful of witnesses, whose trustworthiness is affirmed in the LDS Church, but questioned outside it.