In particular, the clade arising from the ancestral population at node B originated later than the one arising from the original ancestral population at node A . The clade arising from the ancestral population at node B is hierarchically nested within the clade arising from node A . To use an example, mammals are nested hierarchically within the clade of all vertebrate animals. The common ancestor of all vertebrates lived before the common ancestor for all mammals. There are vertebrates that are not mammals, but all mammals are vertebrates.
Mammals are a particular subgroup or part of the whole vertebrate clade.
There are four terminal nodes in this example. The clade arising from node B includes all three ingroup taxa. The purpose of a cladogram is to express a particular hypothesis for the relative branching order of the ingroup taxa. This cladogram example suggests that Taxon 2 and Taxon 3 more recently shared a common ancestor than either does with Taxon 1 . While this hypothesis implies that the ancestral population at node B lived before the ancestral population at node C , it does not stipulate how much earlier it lived.