A CLOSE LOOK AT HOW TWO FOSSIL GROUPS FARED OVER A SHORT INTERVAL OF TIME

A compilation of species abundances within a relatively consistent chronostratigraphic framework is used to examine Middle Devonian fossil groups through time. We chose to scrutinize predetermined, recurring biofacies that, in theory, inherently favor coordinated stasis. Fossil groups are predetermined from hierarchical clustering throughout within an 11-meter outcrop of Central New York. Five groups cluster out, two of which are brachiopod dominated and recur throughout the section (i.e., Devonochonetes cluster and Longispina cluster). Samples within these recurring groups are tested separately for taxonomic stability through time using ANOSIM -- analysis of similarity. When comparing samples within Devonochonetes cluster through time, results indicate younger samples differ significantly from older samples (p < 0.1). Likewise, when comparing Longispina cluster samples, results reflect taxonomic change through time (p < 0.1). Although the type of comparison used should produce evidence for coordinated stasis, we do not find evidence to suggest stability within these predetermined biofacies.