18 JUL 2011 by ideonexus

 Evolution Works With Existing Structures

Ontogeny Recapitulates Phylogeny > Example/Illustration > Skeletal Similarities in Mammals
Evolution adds modifications onto existing structures rather than rewriting organs from scratch. An example of this is in skeletal evolution, where all mammals have the same bones, only in different proportions so that they produce wings, hooves, and other specifically adapted structures.