Maximum recorded size of recent and fossil brachiopods

Changes in predator-prey interactions are often implicated as drivers of
major evolutionary change. A prominent example is the dramatic changes in
shallow marine assemblages during the Mesozoic Marine Revolution (MMR)
when major clades, including rhynchonelliform brachiopods, became
restricted and less diverse. Currently, shallow water temperate and polar
brachiopods can be large, but in the tropics, they are all small. By
contrast, we demonstrate that throughout the Jurassic large brachiopods
occurred in shallow sites, from polar to tropical latitudes, but are
absent in later periods from tropical areas. These changes occurred in
parallel in both major orders (Rhynchonellida and Terebratulida) and also
independently within the two sub-ordinal lineages within the Terebratulida
(terebratulinids and terebratellinids). Increases in both grazing and
predation pressures associated with the MMR might account for this
pattern. However, we note that many current environments support both
large brachiopods and high densities of grazing species and suggest that
the pattern fits more closely to the intensification of durophagous
predation in shallow tropical waters.