P. J. WILLIAMS: Questions about "First Century Mark." (ETC Blog). Good questions, all. It is difficult to imagine how exactly either paleography or C-14 dating could establish that a manuscript was written "during the first century - before the year 90." Neither is that precise, and normally such things are dated something like 100 CE plus or minus 50 years, or maybe 50 CE plus or minus 50 years. And even this level of precision is often not possible. I also wonder how soaking the manuscript with soapy water might corrupt the C-14 dating, but I don't know whether it does or not.
The bottom line is that we have reports of a very early manuscript fragment of the Gospel of Mark, but we are expected for now to take everything about it on faith. We don't know how extensive it is. We don't know if it has interesting textual variants. We don't have a photograph. We have not been presented with scientific data regarding any C-14 dating or paleographical arguments about the date of its script. Now it is certainly possible that this really is a roughly first-century manuscript of Mark. The consensus is that Mark was written around 70 CE, so there is no reason in principle why a fragment of a manuscript copied within twenty or thirty years of the composition of the book couldn't have survived. That would be very lucky indeed, but sometimes we are lucky. But until we have a full publication of the manuscript with all the information listed above, it's just unverified talk. Once we do, if specialists in the relevant areas come to a consensus that it really is a first-century manuscript, no one will be happier than I. But meanwhile I am ... you guessed it ... skeptical.
Just as I was about to press publish, I saw this blog post by Roberta Mazza, which raises additional concerns. Background to the story is here and links.