As Venardi said, taxonomy is always in flux. While the basic classifications are still kingdom, phylum, class, order, family, genus, and species, our research into the evolutionary history of both humans and other organisms has shown that those clear lines are a lot fuzzier than we'd like, so we have other designations like "paraphylum," "superfamily," "subfamily," "superorder," etc. It's also worth remembering that these designations are arbitrary, though scientists do try to apply them consistently. It's just difficult because evolution hasn't followed a very specific, predictable pattern--not even among humans and our ancestors.