Palaeobiogeography and the Ordovician and Mesozoic-Cenozoic biotic radiations

Abstract

Curves of taxonomic diversity through geological time consistently show major evolutionary radiations during the Ordovician Period and from the mid-Mesozoic to the present day. Both intervals were characterized by marked biotic provincialism, reflecting episodes of major continental break-up and global tectonism, and their later histories featured steep global climatic gradients. The Ordovician radiation can be recognized at a wide spectrum of taxonomic levels from species to class, and the biogeographical patterns associated with the radiation of individual clades reflect a complex combination of plate distribution, tectonic activity, sedimentary environment, sea-level rise and, ultimately, glaciation. The true scale of the mid-Mesozoic-Cenozoic biotic radiation is currently a topic of intense debate but there is no doubt that it affected plants and animals in both the marine and terrestrial realms. The role of land bridges and ocean gateways in controlling the formation of biodiversity patterns has been a persistent theme in Mesozoic-Cenozoic biogeography, and a complex set of Neogene tectonic events probably aided the development of both latitudinal and longitudinal provinces during the Cenozoic. The present volume highlights some of the successes across a spectrum of approaches to unravelling the Ordovician and Mesozoic-Cenozoic radiations within the context of palaeobiogeography.'... geologic history is the pacemaker of biologic diversity' (Schopf 1979, p.454) Post-Cambrian curves of taxonomic diversity through geological time consistently show a major evolutionary radiation during the Ordovician Period, and a second, larger one from the mid-Mesozoic to the present day. Between these steep upward slopes the Silurian-Jurassic interval usually appears as a distinct plateau punctuated by mass extinctions and their recovery

Plate tectonic regulation of global marine animal diversity

“…The specific Phanerozoic trajectory of marine animal genus richness remains contested (11,13,(15)(16)(17)21), but analyses consistently reproduce several long-term patterns. A quick rise to a volatile Paleozoic plateau (19), a drop during the end-Permian, a prolonged Early Mesozoic recovery, and a subsequent rise (9,(20)(21)(22) that eventually exceeded the Paleozoic maximum in the Late Mesozoic or Early Cenozoic ( Fig. 2 A and B) are all consistent features of the paleontological literature.…”

“…The correlation improves if the Cambrian-Ordovician, which witnessed the initial evolution and diversification of marine animal communities, is removed from the analysis (range-through ρ = 0.64; in-bin ρ = 0.57). The improvement in correlation is not because the Cambrian-Ordovician exhibits a pattern contrary to the hypothesis; it is an interval of rising biodiversity coincident with supercontinent breakup (20,37,38). However, the Cambrian-Ordovician deviates from the overall pattern in that the magnitude of fragmentation is relatively small (Fig.…”

“…Similarities are particularly well expressed during intervals of increasing continental fragmentation and increasing biodiversity. Continental fragmentation-forced increases in biodiversity have been posited in one form or another for several different times in Earth history (20,37,38). The Cambrian-Ordovician is coincident with the final fragmentation of Rodinia, and the Late Mesozoic increase in biodiversity is concurrent with peak-Phanerozoic fragmentation following the breakup of Pangaea.…”

“…Nevertheless, many major features in the fossil record of biodiversity are consistently reproducible, although not all have universally accepted explanations. In particular, the reasons for a long Paleozoic plateau in marine richness and a steady rise in biodiversity during the Late Mesozoic-Cenozoic remain contentious (11,12,14,(19)(20)(21)(22).…”

Systematic Review of the Flabellidae Family (Scleractinia) of the Pirabas Formation (Lower Miocene), Pará State, Brazil

“…Durante o Oligoceno ocorreram bioeventos de radiação e expansão biogeográfica de formas hermatípicas, trazendo um importante pulso de desenvolvimento de recifes, enquanto que no Mioceno inferior a coralinofauna tornou-se reduzida e tendendo a endêmica (Crame & Rosen, 2002, Owen & Crame, 2002. Observa-se uma marcada diminuição na composição genérica do grupo do Neógeno em direção ao Recente, onde os corais atuais do Pacífico leste e Brasil podem ser considerados como elementos relíquias da associação neogênica da região caribeana (Budd et.…”