STRATIGRAPHIC TESTS OF CLADISTIC HYPOTHESES

Cladograms predict the order in which fossil tara appeared and, thus, make predictions about general patterns in the stratigraphic record. I nconsistencies between cladistic predictions and the observed stratigr aphic record reflect either inadequate sampling of a clade's species, incomplete estimates of stratigraphic ranges, or homoplasy producing a n incorrect phylogenetic hypothesis. A method presented in this paper attempts to separate the effects of homoplasy from the effects of inad equate sampling. Sampling densities of individual species are used to calculate confidence intervals on their stratigraphic ranges. The meth od uses these confidence intervals to test the order of branching pred icted by a cladogram. The Lophospiridae (''Archaeogastropoda'') of the Ordovician provide a useful test group because the clade has a good f ossil record and it produced species over a long time. Confidence inte rvals reject several cladistic hypotheses that postulate improbable '' ghost lineages.'' Other hypotheses are acceptable only with explicit a ncestor-descendant relationships. The accepted cladogram is the shorte st one that stratigraphic data cannot reject. The results caution agai nst evaluating phylogenetic hypotheses of fossil taxa without consider ing both stratigraphic data and the possible presence of ancestral spe cies, as both factors can affect interpretations of a clade's evolutio nary dynamics and its patterns of morphologic evolution.