Glossopteris

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Glossopteris
Glossopteris sp.
Scientific classification Edit this classification
Kingdom: Plantae
Order: †Glossopteridales
Family: †
Glossopteridaceae
Genus: †Glossopteris
Brongniart 1828 ex Brongniart 1831
Species
  • G. angustifolia
  • G. brasiliensis
  • G. browniana
  • G. communis
  • G. indica
  • G. occidentalis
Fossils of the gymnosperm Glossopteris (dark green) found in all of the southern continents provide strong evidence that the continents were once amalgamated into a supercontinent Gondwana

Glossopteris (etymology: from Ancient Greek γλῶσσα (glôssa, " tongue ") + πτερίς (pterís, " fern ")) is the largest and best-known

seed plants known as Glossopteridales (also known as Arberiales, Ottokariales, or Dictyopteridiales). The genus Glossopteris refers only to leaves, within a framework of form genera used in paleobotany. Species of Glossopteris were the dominant trees of the middle to high-latitude lowland vegetation across the supercontinent Gondwana
during the Permian Period. Glossopteris fossils were critical in recognizing former connections between the various fragments of Gondwana: South America, Africa, India, Australia, New Zealand, and Antarctica.

Description

The leaves of Glossopteris are characteristed by their distinctive tongue shape that gives them their name, as well as their

dioecious, the fact that only pollen organ bearing leaves and not ovules were found in some layers suggest that at least some species were the latter.[12]

Distribution

More than 70

gymnosperms such as Pursongia.[23] Confident assignment of fossil leaves to Glossopteris normally requires their co-preservation with the distinctive segmented roots of this group (called Vertebraria) or with the distinctive fertile organs.[24] In 2018, Glossopteris leaves were reported from mid-Permian (Roadian – early Wordian) deposits in Mongolia, then located at high latitudes in the Northern Hemisphere, but these fossils were not found in association with other typical glossopterid organs, such as chambered roots or reproductive structures, so the phylogenetic affinities of these leaves remain uncertain.[25]

Chronology

The Glossopteridales arose in the Southern Hemisphere around the beginning of the

end-Permian mass extinction event.[29]

Taxonomy

Long considered a

Spermatophyta). The genus is in the order Glossopteridales, which is placed in the division Pteridospermatophyta (often informally called "seed ferns"). In reality, many of the plant groups included within this division are only distantly related to one another, and the relationships of Glossopteridales to other seed plant groups is unclear. Some authors have suggested that the Glossopteridales are closely related to flowering plants, though the evidence for such a relationship is weak.[36]

Glossopteris should strictly be used to refer to the distinctive

reticulate venation, however, the term has also been used to refer to the parent plant as a whole.[37] Leaves of Glossopteris are associated with reproductive structures belonging to the family Dictyopteridiaceae within the Glossopteridales.[38]

The name comes from Ancient Greek γλώσσα (glṓssa 'tongue'), because the leaves were tongue-shaped, and πτέρις (pteris 'fern, feathery').[citation needed]

Paleoecology

Reconstruction of trees of Glossopteris at the Middle Permian Onder Karoo locality in South Africa with male (ai) and female (aii) reproductive organs inset

They are interpreted to have grown in very wet soil conditions,[39][40] similar to the modern Bald Cypress. The leaves ranged from about 2 cm to over 30 cm in length.

The profile of glossopterid trees is largely speculative as complete trees have not been preserved. However, based on analogies with modern high-latitude plants, polar-latitude Glossopteris trees have been suggested to have had a tapered, conical profile like that of a Christmas tree and to have been relatively widely spaced to take advantage of the low-angle sunlight at high latitudes,[3] instead of needles, they had large, broad lance- or tongue-shaped leaves commonly with well differentiated palisade and spongy mesophyll layers.

Glossopteris trees are assumed to have been deciduous, as fossil leaves are commonly found as dense accumulations representing autumnal leaf banks.[41][42] The broad fossilized growth rings in Glossopteris woods from Antarctica, then part of Gondwana, reveal that the plants experienced strong growth spurts each spring-summer but underwent the abrupt cessation of growth before each following winter, a transition that could take as little as a month.[43][44] The idea that all Glossopteris species are deciduous has been challenged, with an isotopic study finding that Antarctic Glossopteris forests were mixed evergreen-deciduous.[45]

The Glossopteris bearing plants are likely to have primarily been

wind dispersed. One species Choanostoma verruculosum, may have been adapted to being dispersed by water.[46]

Glossopteris leaves are morphologically simple so there are few characters that can be used to differentiate species.

Gondwanaland (named after the district in India where the plant Glossopteris was found). These same observations would also lend support to Alfred Wegener's Continental drift
theory.

The first Antarctic specimens of Glossopteris were discovered by members of Robert Scott's doomed Terra Nova expedition. The expedition members abandoned much of their gear in an effort to reduce their load, but kept 35 pounds of Glossopteris fossils; these were found alongside their bodies.[48]

See also

  • Dicroidium an extinct corystosperm tree that was widespread and dominant over Gondwana during the Triassic

References

  1. ^ "PBDB". paleobiodb.org.
  2. ^
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  3. ^ a b S. McLoughlin Glossopteris — insights into the architecture and relationships of an iconic Permian Gondwanan plant J. Bot. Soc. Bengal, 65 (2011), pp. 93-106
  4. ^ Weaver, L.; McLoughlin, S.; Drinnan, A.N. (1997). "Fossil woods from the Upper Permian Bainmedart Coal Measures, northern Prince Charles Mountains, East Antarctica". AGSO Journal of Australian Geology and Geophysics. 16: 655–676.
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  7. ^ McLoughlin, S. 1995 Bergiopteris and glossopterid fructifications from the Permian of Western Australia and Queensland. Alcheringa, 19: 175-192.
  8. ^ Adendorff, R., McLoughlin, S. & Bamford, M.K. 2002. A new genus of ovuliferous glossopterid fruits from South Africa. Palaeontologia africana, 38: 1-17.
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  13. ^ Chandra, S. & Surange, K.R. 1979. "Revision of the Indian species of Glossopteris". Monograph 2. Birbal Sahni Institute of Palaeobotany, Lucknow. 301 pp.
  14. ^ McLoughlin, S (1994). "Late Permian plant megafossils from the Bowen Basin, Queensland, Australia: Part 2". Palaeontographica. 231B: 1–29.
  15. ^ McLoughlin, S. 1994. "Late Permian plant megafossils from the Bowen Basin, Queensland, Australia: Part 3. Palaeontographica 231B: 31-62".
  16. ^ Appert, O (1977). "Die Glossopterisflora der Sakoa in südwest Madagaskar". Palaeontographica. 162B (1): 50.
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  21. ^ a b McLoughlin, S (2012). "Glossopteris – insights into the architecture and relationships of an iconic Permian Gondwanan plant". Journal of the Botanical Society of Bengal. 65 (2): 1–14.
  22. ^ Meyen, S.V., 1987. Fundamentals of palaeobotany Chapman and Hall, London. 432 pp.
  23. ^ Zimina, V.G. (1967). "On Glossopteris and Gangamopteris in Permian deposits of the Southern Maratime Territory". Paleontological Journal. 2: 98–106.
  24. ^ McLoughlin, S., 2012." Glossopteris – insights into the architecture and relationships of an iconic Permian Gondwanan plant". Journal of the Botanical Society of Bengal 65(2), 1–14.
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  32. ^ Pant, D.D.; Pant, R. (1987). "Some Glossopteris leaves from Indian Triassic beds". Palaeontographica. 205B: 165–178.
  33. ^ Anderson, J. M. & Anderson, H. M., 1985. "Palaeoflora of southern Africa. Prodomus of southern African megafloras Devonian to Lower Cretaceous". A.A. Balkema, Rotterdam. 423 pp.
  34. ^ Delevoryas, T. & Person, C.P. 1975. "Mexiglossa varia gen. et sp. nov., a new genus of glossopteroid leaves from the Jurassic of Oaxaca, Mexico". Palaeontographica A 154, 114-120.
  35. ^ Brongniart, A., 1828a-38: Histoire des végétaux fossiles on researches botaniques et géologiques sur les végétaux renfermés dans les diverses couches du globe. G. Dufour & Ed. D'Ocagne, Paris. XII+488 pp. (Vol. I) / Crochard et Compagnie, Paris. 72 pp. (Vol. II).
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  43. ^ Ryberg, P.E., & Taylor, E.L., 2007. Silicified wood from the Permian and Triassic of Antarctica: Tree rings from polar paleolatitudes. In Antarctica: A Keystone in a changing world; proceedings of the 10th International Symposium on Antarctic Earth Sciences, A. K. Cooper, P. J. Barrett, H. Stagg, B. Storey, E. Stump, W. Wise, and the 10th ISAES editorial team [eds.], U.S. Geological Survey Open-File Report 2007-1047, Short Research Paper 080. National Academies Press, Washington, D.C., USA.
  44. ^ UWM geologists uncover Antarctica's fossil forests
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  48. Jerry A. Coyne, 2009, Penguin Books
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Sources

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