Paleobiogeography of Mesozoic high-latitude radiolarians: Progress and problems

Abstract Radiolarians of the Mesozoic display strong provincialism. High-latitude assemblages differ from the low-latitude ones by low taxonomic diversity, the presence of characteristic taxa that are common only in high-latitude regions (as Glomeropyle for the Middle Triassic, Parvicingula with apical horn, Praeparvicingula and Echinocampidae ( Echinocampe , Nordvikella and Arctocapsula ) for the Late Jurassic–earliest Cretaceous, and Prunobrachiidae ( Prunobrachium and Pseudobrachium ) for the Late Cretaceous), and by domination of certain morphotypes such as pylomate spheres for the Middle Triassic or spongy discoids and spongy prunoids for the Late Cretaceous. Paleobiochores for some intervals of the Mesozoic (Middle and Late Triassic, Late Jurassic and Late Cretaceous) are proposed. The main problem of the Mesozoic radiolarian paleobiogeography is insufficient knowledge of high-latitude radiolarian assemblages, especially those of the Early Jurassic, and Early Cretaceous.