Arcto-Tertiary Geoflora

From Wikipedia, the free encyclopedia

The Arcto-Tertiary Geoflora is a hypothesized floral assemblage that once covered the Northern Hemisphere, from roughly the late Mesozoic to mid Cenozoic Eras.

[edit] Origins

First proposed by the paleobotanists J.S. Gardner and C. Ettinghausen in 1879, the concept was intended to answer questions about the disjunct distribution of identical or closely-related plant species: for instance, magnolia and tulip trees are native to both the Southeast United States and southern China and Indochina.[1], [2]

As envisioned, the ATG had a wide distribution when the global climate was much warmer than it is currently, a situation strengthed by the closer position of some of the continents in late Mesozoic to early Cenozic times.[3],[4] With the onset of global cooling and the Ice Ages, the ranges of these tropical to subtropical species were left in isolated pockets of warmer climates.[5]

The southern, more tropical equivalent of the ATG was the Neotropical Tertiary Geoflora.[6]

[edit] Footnotes:

  1. ^ Delcourt, Hazel, Forests in Peril, (Blacksburg: The McDonald and Woodward Publishing Company, 2002), 31-2.
  2. ^ Dougal Dixon et al., The Atlas of Life on Earth, (New York: Barnes & Noble Books, 2001), 334-5.
  3. ^ Delcourt, 31.
  4. ^ Dixon et al., 334.
  5. ^ Delcourt, 32.
  6. ^ Ibid.

[edit] External links:

http://www.radford.edu/~swoodwar/CLASSES/GEOG235/biomes/tbdf/arcto.html