The fossil needed to support the phylogeny is a common ancestor of both the hippo and the whale and would consist of characteristics from both species. Specifically it would have the pulley shaped astragalus. The common ancestor of the whale and hippo diverged and created 2 seperate species, hippo and whale. This was done when the whale mutated and lost the oulley shaped astragulus, while the hippo still has that characteristic to this day. The common ancestor is an animal that consists of both whale and hippo characreristics, which characteristics other than the pulley shaped astragulus, we may never know. The requirement for the pulley shape because using the idea of maximum parsimony leads us to want the least amount of evolutionary changes. It would make much more sense and be much easier for the whale to lose the pulley shaped astragulus and the common ancestor of the whale and the hippo to have it, than for the common ancestor to lose the characteristic and for the hippo to independetly gain it back. It makes much more sense to say the common ancestor contained the pulley shaped astragalus, and had some whale characteristics.
Recent comments