The Contribution of Morphological Variation to Stratigraphic Longevity in Cambrian Trilobite Species
Despite the potential importance of morphological variation in structuring evolutionary patterns, spatially and temporally, little is known about how relative differences in variation across taxa contribute to differences in duration.
This gap in our understanding is ameliorated by comparing pairs of closely related trilobite species from the Steptoean (Furongian, Cambrian) of the Great Basin, USA. Relative durations are estimated using a composite section of continent-wide (Laurentian) occurrences of Steptoean taxa based on correlation using constrained optimization, but are not included in the correlation itself. Variation is assessed using geometric morphometric analysis of fossil material preserved in limestone, some silicified. Comparisons of cogeneric species with similar geographic range sizes but different durations (and vice versa) will allow an initial assessment of how morphological variation contributes to trilobite survivorship.