Diversity of coralline red algae: origination and extinction patterns fromthe Early Cretaceous to the Pleistocene

Data from a comprehensive literature survey for the first time provide stag e-level resolution of Early Cretaceous through Pleistocene species diversit y for nongeniculate coralline algae. Distributions of a total of 655 specie s in 23 genera were compiled from 222 publications. These represent three f amily-subfamily groupings each with distinctive present-day distributions: (1) Sporolithaceae low latitude mainly deep water; (2) Melobesioid corallin aceans, high latitude, shallow water, to low latitude, deep water; (3) Lith ophylloid/mastophoroid corallinaceans, mid- to low latitude, shallow water Raw data show overall Early Cretaceous-early Miocene increase to 245 specie s in the Aquitanian, followed by collapse to only 43 species in the late Pl iocene. Rarefaction analysis confirms the pat tern of increase but suggests that scarcity of publications exaggerates Neogene decline, which was actua lly relatively slight. Throughout the history of coralline species, species richness broadly corre lates with published global paleotemperatures based on benthic foraminifer delta O-18 values. The warm-water Sporolithaceae were most species-abundant during the Cretaceous, but they declined and were rapidly overtaken by the Corallinaceae as Cenozoic temperatures declined. Trends within the Corallinaceae during the Cenozoic appear to reflect envir onmental change and disturbance. Cool- and deep-water melobesioids rapidly expanded during the latest Cretaceous and Paleocene. Warmer-water lithophyl loid/mastophoroid species increased slowly during the same period but more quickly in the early Oligocene, possibly reflecting habitat partitioning as climatic belts differentiated and scleractinian reef development expanded near the Eocene/Oligocene boundary. Melobesioids abruptly declined in the l ate Pliocene-Pleistocene, while lithophylloid/mastophoroids increased again . possibly onset of glaciation in the Northern Hemisphere (similar to2.4 Ma ) sustained or accentuated latitudinal differentiation and global climatic deterioration, disrupting high-latitude melobesioid habitats. Simultaneousl y this could have caused moderate environmental disturbance in mid- to low- latitude ecosystems, promoting diversification of lithophylloids/mastophoro ids through the "fission effect." Extinction events that eliminated >20% of coralline species were most sever e (58-67% of species) during the Late Cretaceous and late Miocene-Pliocene. Each extinction was followed by substantial episodes of origination, parti cularly in the Danian and Pleistocene.