Is 7Q5 a Fragment of Mark?

I came across reference to 7Q5 at this blog (originally from here).

7Q5 is a fragment of a scroll found at Qumran - part of the famous Dead Sea Scrolls. If the fragment really is part of Mark, specifically Mark 6:52-53, that would date Mark to around AD 50, significantly earlier than the usual dating of AD 70.

From the blog:

"A final piece of evidence comes from the Dead Sea Scrolls Cave 7. Jose Callahan discovered a fragment of the Gospel of Mark and dated it to have been written in A.D. 50. He also discovered fragments of Acts and other epistles and dated them to have been written slightly after A.D. 50."

This is what the fragment looks like (image is from Wiki commons), so you can see how small it is and how many letters are present:

There is an excellent web pages on this topic at Bible.org, which is a nondenominational Christian web site that appears to be well respected. From the conclusion:

First, what is the hard evidence on which O’Callaghan’s identification is based? A scrap of papyrus smaller than a man’s thumb with only one unambiguous word—και. Only six other letters are undisputed: τω (line 2), τ (line 3, immediately after the και), νη (line 4), η (line 5). To build a case on such slender evidence would seem almost impossible even if all other conditions were favorable to it. But to identify this as Mark 6:52-53 requires (1) two significant textual emendations (tau for delta in a manner which is unparalleled; and the dropping of ἐπὶ τὴν γῆν even though no other MSS omit this phrase); and (2) unlikely reconstructions of several other letters. Add to this that the MS is from a Qumran cave and that it is to be dated no later than 50 CE and the case against the Marcan proposal seems overwhelming. If it were not for the fact that José O’Callaghan is a reputable papyrologist and that C. P. Thiede is a German scholar, one has to wonder whether this hypothesis would ever have gotten more than an amused glance from the scholarly community.