"Archaeopteryx; bird or reptile, or both?"

The real question is whether archaeopteryx should be considered a transitional. Given that it is considered a basal or near basal member of aves surely that answer is yes. The basal members, by definition, must include some 'primitive' traits from the clade they are derived from which are replaced by derived traits in the crown group.

I recognise the limits of cladistics - although it seems to me that the reason behind it is a generalisation that is not always true. (That is there is a small proportion of cases where we can identify that one species did descend from another).Archaeopteryx ought to be considered more transitional than most species because birds are so greatly modified from their dinosaurian ancestors and because it shares such a mix of avian and dinosaurian features (and at least one feature - brain sixe - that appears to be intermediate in itself).