Abstract: I use 16,000 galaxy spectra from the Sloan Digital Sky Survey to probe the varying stellar populations of early type galaxies throughout the Fundamental Plane. Not only do early type galaxies span a 2 - dimensional family in the Fundamental Plane, but they appear to span a 2-dimensional family in star formation histories. In addition to known variations with galaxy mass, I present evidence that stellar populations in these galaxies are intimately linked with their central dark matter fractions, revealing a connection between star formation history and structural evolution. I discuss these results in the context of different models for galaxy evolution in a hierarchical universe.