Data from: Environmental and scale-dependent evolutionary trends in the body size of crustaceans

The ecological and physiological significance of body size is well
recognized. However, key macroevolutionary questions regarding the
dependency of body size trends on the taxonomic scale of analysis and the
role of environment in controlling long-term evolution of body size are
largely unknown. Here, we evaluate these issues for decapod crustaceans, a
group that diversified in the Mesozoic. A compilation of body size data
for 792 brachyuran crab and lobster species reveals that their maximum,
mean and median body size increased, but no increase in minimum size was
observed. This increase is not expressed within lineages, but is rather a
product of the appearance and/or diversification of new clades of larger,
primarily burrowing to shelter-seeking decapods. This argues against
directional selective pressures within lineages. Rather, the trend is a
macroevolutionary consequence of species sorting: preferential origination
of new decapod clades with intrinsically larger body sizes. Furthermore,
body size evolution appears to have been habitat-controlled. In the
Cretaceous, reef-associated crabs became markedly smaller than those in
other habitats, a pattern that persists today. The long-term increase in
body size of crabs and lobsters, coupled with their increased diversity
and abundance, suggests that their ecological impact may have increased
over evolutionary time.