The De Geer, Thulean and Beringia routes: key concepts for understanding early Cenozoic biogeography

Abstract

Aim I re-evaluate the specific biogeographical significance of each of the land bridges (Beringia, Thulean and De Geer) in the Northern Hemisphere during the latest Cretaceous-early Cenozoic, showing that the Thulean and De Geer routes did not operate contemporaneously.Location Northern Hemisphere landmasses.Methods I review the recent climatic, sea-level, geotectonic, palaeofloristic, and marine and terrestrial faunal data that have emerged since the establishment in the 1980s of the biogeographical concepts of the early Cenozoic Northern Hemisphere land bridges and present a synthesis supporting a revised scenario for early Cenozoic biogeographical development.Results Palaeogeographical and geotectonic data, supported by strong floral and faunal evidence, suggest that the palaeogeographical and chronological frames for the formation of all three land bridges are different from those originally proposed. Dispersal events via the causeways seem to have taken place during specific time intervals resulting from fluctuations in sea level and climate.

Copepod Mandible Palynomorphs From the Nolichucky Shale (Cambrian, Tennessee): Implications for the Taphonomy and Recovery of Small Carbonaceous Fossils

“…The further we are from these continents the lower species richness can be observed: ten species live in the Western Palearctic, nine in Middle America, seven in Australia (five of those are recently moved to the genus Pescecyclops erected by Karanovic et al 2011), five in the Oriental region (India + SE Asia), four in East Asia (two of which are shared with the Oriental), two in Siberia (shared with western Palearctic), two in North America, and one in Madagascar (shared with Africa) (Dussart and Defaye 2006;Defaye and Por 2010;Mercado-Salas et al 2013 Van Damme and Sinev (2013). According to this scenario, the ancestor of Apocyclops could have originated in North America and/or Eastern Palearctic in the Paleocene-Eocene, when a much warmer climate allowed dispersal of the warm-temperate-tropical fauna between Siberia and Alaska across Beringia (Sanmartín et al 2001;Brikiatis 2014). In the early Cenozoic the Beringian land bridge was exposed in the early (66-65 mya) and late Paleocene (in a short period between 59 and 58 mya).…”

Amphibians crossing the Bering Land Bridge: Evidence from holarctic treefrogs (Hyla, Hylidae, Anura)

“…In the Northern Hemisphere, i.e., the Holarctic biogeographical realm, several subaerial dispersal routes have been discussed that potentially allowed Cenozoic faunal (and floral) exchange between North America, western Eurasia, and Eastern Eurasia: The Bering Land Bridge between East Asia and North America; the connection across Turgai Strait between western and eastern Eurasia; and two dispersal corridors from western Eurasia to North America, one connecting Greenland and Fennoscandia (the 'DeGeer route') and one connecting Western Europe with Greenland via what is now the Northeast Atlantic (the 'Thulean route'; see Brikiatis, 2014, and references therein). While the DeGeer and Thulean dispersal corridors operated as early as the Late Cretaceous/Early Paleocene and Late Paleocene/Early Eocene, respectively, a subaerial connection via the Bering Land Bridge occurred more frequently during the Cenozoic.…”

Worldwide long‐distance dispersal favored by epizoochorous traits in the biogeographic history of Omphalodeae (Boraginaceae)

“…In addition, the LDD between distant Mediterranean and Sierra Madre regions in more recent times (mainly Miocene) has been also hypothesized to explain this pattern (Raven & Axelrod, ). Given that the date of Madrean‐Thethyan disjunction in Omphalodeae (Oligocene‐Miocene boundary) is posterior to the disappearance of the North Atlantic Bridge (late Palaeocene; Tiffney, ; Brikiatis, ), the hypothesis of more recent LDD is more plausible. Indeed, there are other well‐known examples of LDD from Old to New World even during Quaternary, such as the species of genus Oligomeris (Martín‐Bravo et al, ).…”