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| Laurasian | |
|---|---|
| Name | Laurasia |
| Period | Mesozoic–Cenozoic |
| Status | Former supercontinent landmass |
| Caption | Reconstruction of northern hemisphere continents during the Late Jurassic |
| Major components | North America, Eurasia, Greenland, Iceland |
| Notable fossils | Archaeopteryx, Tyrannosaurus, Triceratops |
| Formed | After breakup of Pangaea |
| Separated from | Gondwana |
| Significance | Holarctic biogeographic province |
Laurasian
Laurasian denotes the northern supercontinental assemblage that dominated Northern Hemisphere continental configurations following the fragmentation of Pangaea in the Mesozoic. It underpins modern continental outlines including North America, parts of Eurasia, and Greenland, and is central to interpretations of Mesozoic–Cenozoic paleogeography, paleoclimate, and vertebrate dispersals across the Holarctic. Studies of Laurasian stratigraphy and tectonics draw on work from institutions such as the Smithsonian Institution, Natural History Museum, London, and research programs at University of Cambridge and University of California, Berkeley.
The term derives from the compound of the medieval toponym Laurasia as coined in 19th–20th century paleogeographic literature associated with scholars at University of Chicago and Columbia University. Early definitions contrasted Laurasia with Gondwana in syntheses by researchers linked to Geological Society of America, the Royal Society, and figures such as Alfred Wegener and later proponents in the tradition of Arthur Holmes. Modern usage in publications from American Museum of Natural History and the European Geosciences Union defines Laurasia as the northern continental block that resulted from the rift of Pangaea and which subsequently underwent fragmentation into constituent plates now recognized as parts of Laurentia, Baltica, and Siberia in plate reconstructions published by teams at ETH Zurich and Massachusetts Institute of Technology.
The geological history of the Laurasian assemblage is traced through stratigraphic columns, paleomagnetic data, and marine transgression records compiled by groups at United States Geological Survey, British Geological Survey, and Geological Survey of Canada. From Late Triassic rifting linked to Central Atlantic Magmatic Province, Laurasia occupied high northern latitudes through the Jurassic and Cretaceous, with seaways such as the Western Interior Seaway cutting across North America and epicontinental shelves forming along Europe and Asia Minor. Reconstructions by researchers at Caltech and Paleontological Society use fossil ranges from sites like the Dinosaur Provincial Park and Solnhofen Limestone to refine paleogeographic maps. Throughout the Paleogene and Neogene, tectonic processes involving the North American Plate, Eurasian Plate, and microplates such as the Iberian Plate and Adria reshaped coastlines, culminating in configurations documented by the International Union of Geological Sciences.
Fossil assemblages from Laurasian sediments show characteristic suites of plants and animals studied by museums including the Field Museum and the Royal Ontario Museum. Mesozoic Laurasia hosted gymnosperm-dominated floras with representatives preserved at Yixian Formation and Green River Formation, alongside early angiosperm radiations documented from Crato Formation and Cretaceous Research field sites. Vertebrate faunas include iconic genera such as Allosaurus, Stegosaurus, Velociraptor, and avian-like Archaeopteryx; Cenozoic successions record expansions of Equus, Mammuthus, and diverse carnivorans tracked by paleontologists at Natural History Museum, Vienna and American Museum of Natural History. Paleobotanical and palynological studies conducted at Smithsonian Institution and Royal Botanic Gardens, Kew contribute to reconstructions of Laurasian vegetation shifts.
Plate-tectonic models describing Laurasia’s breakup rely on paleomagnetic poles, seafloor spreading chronologies from the Mid-Atlantic Ridge, and tomographic imaging produced by collaborations including IRIS and NOAA. Key events include the opening of the North Atlantic Ocean between Laurentia and Baltica and the eventual isolation of Greenland and Iceland via rifting episodes recorded in the Cenozoic magnetic anomaly record. The collision of terranes such as the Taconic and Alleghanian orogens with the North American margin, and the accretion of the Ural Mountains to form parts of Eurasia, are central in syntheses from University of Oxford and Seismological Society of America publications. Plate reconstructions by teams at NOAA and Lamont–Doherty Earth Observatory illustrate sequential fragmentation into plates recognized today.
Laurasian climate history is reconstructed from isotope stratigraphy, leaf physiognomy, and sedimentological evidence published in journals supported by European Geosciences Union and American Geophysical Union. The Mesozoic greenhouse conditions recorded in Laurasian basins contrast with Paleogene cooling tied to events like the Paleocene–Eocene Thermal Maximum and later Neogene cooling trends associated with southern ocean gateways studied by researchers at Scripps Institution of Oceanography and University of Cambridge. Regional climate drivers include the development of the Jet Stream pattern over northern continents and changing oceanic gateways such as the Bering Strait and Tethys Ocean margins, with proxy records curated by the PAGES community.
Laurasia functioned as the principal arena for Holarctic biogeographic exchanges analyzed in frameworks advanced by the International Biogeography Society and authors publishing in Journal of Biogeography. Over the Mesozoic–Cenozoic interval, corridors and barriers—such as the Bering Land Bridge, the North Atlantic Land Bridge, and temporary Arctic gateways—mediated dispersal events involving lineages documented in studies from Smithsonian Institution, Natural History Museum, London, and Canadian Museum of Nature. Paleontological evidence shows interchange between Laurasian and Gondwanan lineages through episodic dispersal via microplates and island chains implicated in scenarios proposed by researchers at University of Toronto and Monash University. Patterns of endemism across modern North America and Eurasia reflect the legacy of Laurasian vicariance, as synthesized by global inventories compiled by institutions like IUCN and the World Wildlife Fund.
Category:Prehistoric continents