Really? What is the reason for knowing a priori that scleromochlids
could not possibly be paraphyletic with respect to pterosaurs?
There is only one known scleromochlid, *Scleromochlus* itself, and it has
autapomorphies, so the most parsimonious assumption is that it's not an
ancestor of anything else we know -- never mind its geological age, which
IIRC isn't older than the oldest known pterosaurs.
And then there's the widely acknowledged principle that only monophyletic
taxa should be named above the species level. If there were two
scleromochlids known, and the group as a whole turned out to be
paraphyletic, that would mean one of the scleromochlids had turned out not
to be a scleromochlid.