Cheilostome cyclostome assemblage 2020

Examining the supposition that local-scale competition drives
macroevolutionary patterns has become a familiar goal in fossil
biodiversity studies. But it is an elusive goal, hampered by inadequate
confirmation of ecological equivalence and interactive processes between
clades, patchy sampling, few comparative analyses of local species
assemblages over long geologic intervals, and a dearth of appropriate
statistical tools. We address these concerns by reevaluating one of the
classic examples of clade displacement in the fossil record, in which
cheilostome bryozoans surpass the once dominant cyclostomes. Here, we
analyze a newly expanded and vetted compilation of 40,190 fossil species
occurrences to estimate cheilostome and cyclostome patterns of species
proportions within assemblages, global genus richness, and genus
origination and extinction rates while accounting for sampling. Comparison
of time series models using linear stochastic differential equations
suggests that inter-clade genus origination and extinction rates are
causally linked to each other in a complex feedback relationship rather
than by simple correlations or unidirectional relationships, and that
these rates are not causally linked to changing within-assemblage
proportions of cheilostome versus cyclostome species.