 Other discussions on the interface between development and evolution focus on the structure of explanations that address how developmental mechanisms evolve. Calcott (2009, 2013) has argues that Mayr’s distinction characterizes two kinds of explanation: developmental explanation that answers ‘How do individuals work at a time?’ and evolutionary explanation that answers ‘How do populations change over time?’ However, there is a third kind, called ‘lineage explanation’. Lineage explanation differs from the above by answering ‘How do individuals change over time?’ Therefore, they offer a series of mechanistic models, which trace differences between the developmental mechanisms of individuals that produce the relevant morphological structures at different times. Over evolutionary time, these relations undergo small modifications, which ultimately bring about novelties, like eyes and feathers, in the whole system. Thus, lineage explanation expands the standards philosophical framework from a single description of a mechanism into a series of mechanistic models.