Fig. 272: Early development in mammal groups based on the example of cotyledons and amnion development in diagrammatic cross-sections.
It is shown that in spite of similar class-typical principles of development, there are still individual differences between individual mammal groups. The hedgehog as a example of an insectivore, a mammal group considered primitive, demonstrates a more similar course of development to humans than for example prosimians, which - seen phylogenetically - are much closer to humans. As with many other examples, this proves that evolutionary relationships cannot be deduced on the basis of similarities in embryonic development.