Types of organisms have arisen via natural selection and speciation. Within Primates newer forms are more neotonous. This trends probably arise via unequal speciation and extinction rates. A group is monophyletic if it includes a common ancester and ALL its descendent species. For example two members of Class Aves share an ancestral bird, and two members of Class Mammalia share an ancestral mammal, but as we move down the classification all for species share an ancestral invertebrate, and so are placed in the Phylum Chordata.
Homology is similarity by descend.
Begin by acting as if all traits are homologous. Cladistics or Phylogenetic Systematics. Only shared characters are important because if only one taxon has the character, the character says nothing about grouping. A worked example without conflicts. The order of the evolutionary appearance of traits.