I thought that according to cladistics, only monophyletic groups were valid as species or any other taxa. But extinct species, like say H Erectus must be paraphyletic, as the common ancestor of H Erectus is also the common ancestor of modern man. So if species are frequently paraphyletic, how can cladistics be tenable?
Edit. Also, I'm new to this forum. The people responding here, I'm assuming are actually biologists with a specific knowledge of cladistics, right? I'm a post-grad (philosophy of biology rather than biology per se) so I'm not really looking for links which explain what cladistics is, and certainly not wikipedia. I can access most journals if there is a paper on this subject. I can't find anyone in our dept who can give me a steer on this. I realise thhis is a slightly unorthodox research method, but I'm at a bit of a dead end here!