CONCLUSIONS

  1. Paleocommunity analysis at the family, species, and abundance levels yielded different patterns of paleoecological information.
  2. Among populations that are closely spaced stratigraphically, significant differences in shape and growth patterns were detected in "P." thompsoni using landmark morphometrics. These differences are consistent with changes in paleoenvironmental conditions.
  3. Simple morphological analysis (for example, size only) would not have been sufficient to detect the morphological differences documented between samples.
  4. Paleocommunity analysis complements morphological studies of microevolutionary processes by (a) providing a context for evolutionary change and (b) indicating species that are ideal candidates for examining how paleoecological changes may be reflected in morphology.