Thomas is (purportedly) a collection of the sayings of Jesus, and contains no dragons or giant crosses or the like. Plus, given the difficulty of dating early Christian works, as discussed below, the provenance of Thomas is, for the moment, about as good as it is for any of the canonical gospels. One may debate whether it is divinely inspired or not, but the historical and archaeological evidence does not resolve that debate in and of itself.
Finally, if we look at the history of New Testament development, we find that by about 160AD we have a copy of the New Testament that is essentially what we use today....
There is no real support for such precise dating in the archaelogical and historical record, and such a contention is almost purely a matter of opinion, rather than of fact. The written gospels almost certainly predate the second century, but by how much, no one can really say with any certainty.