 Philosophers of biology (in the so-called new mechanistic philosophy) have conceptualized mechanistic explanations in biology as the construction of models of mechanisms that connect parts of systems, located on one level of organization, with behaviors of the whole system, usually located on a higher level of organization (Machamer et al. 2000; Craver 2007; Illari &amp; Williamson 2012). In this framework, mechanistic models relate different compositional levels of organization, like genes and phenotypes or cells and tissues. These inter-level relations exist between causal capacities of parts of a system and their organization and the capacities of a system as a whole. Such relations are established following a procedure of decomposition and localization (Bechtel &amp; Richardson 1993; Craver 2007; Menzies 2012). This conceptual framework to describe biological mechanisms and mechanistic explanation has been developed based on case studies in molecular and cell biology. However, scholars have cast doubt on whether it is also useful to describe mechanistic explanations in studies of development and developmental evolution.