Quantifying morphological change during an evolutionary radiation of Devonian trilobites

The fossil record provides an important source of data on adaptive radiations, and indeed some of the earliest theoretical insights on the nature of these radiations were made by paleontologists. Here we focus on the diverse Devonian Metacryphaeus group calmoniid trilobites, known from the Malvinokaffric Realm; these have been considered a classic example of an adaptive radiation preserved in the fossil record. A geometric morphometric analysis is used in conjunction with phylogenetic and biogeographic patterns and data on speciation rates. Patterns of morphological change are quantified using ancestral character state reconstruction during speciation events in order to assess the role ecological and geographical factors may have played in mediating this radiation. No significant differences were found between the amount of morphological change that occurred during speciation events when ancestors and descendents were in the same area as opposed to when they occupied different areas. Fu...