I also have worked with a more obscure and entirely extinct group, the Rostroconchia . The primary purpose of this phylogenetic work is to provide a template for the macroevolutionary studies discussed below. However, it also has resulted in an extensive taxonomic revision of Early Paleozoic gastropods . The main macroevolutionary issues that I have studied concern rates of morphologic evolution. I have been particularly interested in how those rates might change over time, especially after the early Paleozoic.
Gastropods represent one such taxon.
The bulk of gastropod morphospace was produced very rapidly. Subsequent evolution in the major clades failed to produce the same range of variation even after the evolution of many more species over many tens of millions of years. When morphologic separations between ancestors and descendants were examined, a highly significant decrease over time was found. Intriguingly, the decrease focused on particular types of shell differences. Among modern snails, these types of differences are observed among taxa with very different soft anatomies.