Lazarus taxon

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The takahe is an example of a Lazarus taxon.

In paleontology, a Lazarus taxon (plural taxa) is a taxon that disappears from one or more periods of the fossil record, only to appear again later. The term refers to the account in the Gospel of John, in which Jesus raised Lazarus from the dead. Lazarus taxa are observational artifacts that appear to occur either because of (local) extinction, later resupplied, or as a sampling artifact. If the extinction is conclusively found to be total (global or worldwide) and the supplanting species is not a lookalike (an Elvis species), the observational artifact is overcome. The fossil record is inherently imperfect (only a very small fraction of organisms become fossilized) and contains gaps not necessarily caused by extinction, particularly when the number of individuals in a taxon becomes very low. If these gaps are filled by new fossil discoveries, a taxon will no longer be classified as a Lazarus taxon.

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[edit] Terminology

The terms "Lazarus effect" or "Lazarus species" have also found some acceptance in neontology — the study of extant organisms, as contrasted with paleontology — as an organism that is rediscovered alive after having been widely considered extinct for years (a recurring IUCN Red List species for example). Examples include Jerdon's courser, the ivory-billed woodpecker (disputed), the Mahogany Glider and the takahē, a flightless bird endemic to New Zealand.[1] However, in these cases being "extinct" strongly relates to the sampling intensity of the IUCN, and that such a period of apparent extinction is too short for species to be designated as "Lazarus taxa" (in its paleontological meaning).

Lazarus taxa that reappear in nature after being known only as old enough fossils can be seen as an informal subcategory of the journalist's "living fossils", because a taxon cannot become globally extinct and reappear. If the original taxon went globally extinct, the new taxon must be an Elvis taxon. On the other hand, all species "correctly considered living fossils" (with all conditions fulfilled, living and found through a considerable part of the geologic timescale) cannot be Lazarus taxa.

[edit] Reappearing species

[edit] Cryptozoology

Animals that are Lazarus taxa are often cited by Cryptozoologists as former Cryptids.[1][2]

[edit] Reappearing fossil taxa

Coelacanth Latimeria chalumnae.
  • Coelacanth (Latimeria), a member of a clade (Coelacanthimorpha) thought to have gone extinct 65 million years ago; found in 1938.
  • Monoplacophora, a class of molluscs believed to have gone extinct in the middle Devonian Period (c. 380 million years ago) until living members were discovered in deep water off Costa Rica in 1952.
  • Laotian Rock Rat (Laonastes aenigmamus), a member of a family (Diatomyidae) thought to have gone extinct 11 million years ago; found in 1996.
  • Monito del Monte (Dromiciops), a member of a clade (Microbiotheria) thought to have gone extinct 11 million years ago.
  • Lazarussuchus, an Oligocene member of a clade of freshwater reptiles (Choristodera) thought to have gone extinct at the end of the Mesozoic. As Lazarussuchus is thought to be outside the clade including other choristoderans, it may indicate a ghost lineage going back to the Late Triassic, a span of over 170 million years.
  • Majorcan midwife toad, an Amphibian, first described from the fossil record. Later the species was 'rediscovered' in 1979 when froglets and young frogs were discovered.
  • Gracilidris, a genus of dolichoderine ants thought to have gone extinct 15-20 million years ago was found in Paraguay, Brazil, and Argentina and described in 2006.
  • Dawn Redwood or Metasequoia, a genus of conifer, was first described as a fossil from the Mesozoic Era by Shigeru Miki in 1941, but in 1943 a small stand was discovered in China in Modaoxi by Zhan Wang.
  • Wollemi Pine (Wollemia), a species previously known only from fossils from 2 to 90 million years old representing a new genus of Araucariaceae, was discovered in 1994.
  • Nightcap Oak (Eidothea hardeniana and E. zoexylocarya), representing a genus previously known only from fossils 15 to 20 million years old, were recognized in 2000 and 1995, respectively.
  • Chacoan Peccary (Catagonus wagneri), known to scientists only from fossils before its discovery in 1975.[3]
  • Mountain Pygmy Possum (Burramys parvus), Australia's only truly hibernating marsupial, known originally from the fossil record and then discovered in 1966.

[edit] Reappearing IUCN red list species

[edit] Plants

Café marron Ramosmania rodriguesii.

[edit] Protostomes

[edit] Fish

  • black kokanee (Oncorhynchus nerka kawamurae) Believed extinct in 1940, rediscovered in 2010
    Atelopus nahumae.

[edit] Amphibians

[edit] Mammals

[edit] Reptiles

[edit] Birds

[edit] See also

[edit] References

  1. ^ a b Shuker, Karl P N (2002). The New Zoo: New and Rediscovered Animals of the Twentieth Century. House of Stratus. 
  2. ^ *Heuvelmans, Bernard. On The Track Of Unknown Animals. (New York: Hill and Wang, 1959.
  3. ^ Naish, Darren (2008-11-24). "New, obscure, and nearly extinct rodents of South America, and... when fossils come alive". Tetrapod Zoology. http://scienceblogs.com/tetrapodzoology/2008/11/new_obscure_and_nearly_extinct.php#more. Retrieved 2008-12-13. 
  4. ^ C.A. McGuinness (2004). Xylotoles costatus. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 17 March 2007.
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