The Cretaceous Terrestrial Revolution (abbreviated KTR), also known as the Angiosperm Terrestrial Revolution (ATR) by authors who consider it to have lasted into the Palaeogene,[1] describes the intense floral diversification of flowering plants (angiosperms) and the coevolution of pollinating insects, as well as the subsequent faunal radiation of frugivorous, nectarivorous and insectivorous avians, mammals, lissamphibians, squamate reptiles and web-spinning spiders during the Cretaceous period.
[4] The KTR was enabled by the dispersed positions of the continents and the formation of new oceans during the Cretaceous in the aftermath of Pangaea's breakup in the preceding Jurassic period, which enhanced the hydrological cycle and promoted the expansion of temperate climatic zones, fuelling radiations of angiosperms.
This enabled greater utilisation of CO2 and gave an evolutionary advantage to flowering plants over conifers because they could sequester more CO2 for the same amount of water.
[10] Although angiosperm diversity drastically grew over the Cretaceous, this did not necessarily translate to ecological dominance, which they only achieved in the Early Cenozoic.
[12] Before Lloyd et al.'s 2008 paper described the KTR, it had been widely accepted in paleontology that new families of dinosaurs evolved during the Middle to Late Cretaceous, including the euhadrosaurs, neoceratopsians, ankylosaurids, pachycephalosaurs, carcharodontosaurines, troodontids, dromaeosaurs and ornithomimosaurs.
[16] A comprehensive molecular study of evolution of mammals at the taxonomic level of family also showed important diversification during the KTR.
[34] The so-called "golden age" of neuropterans during the Middle Mesozoic, when gymnosperms dominated the flora, ended with the KTR and its reshaping of the terrestrial environment.
[35] The KTR may have supercharged the contemporary Mesozoic Marine Revolution (MMR) by enhancing weathering and erosion, accelerating the flow of limiting nutrients into the world’s oceans.