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.

Contents

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.

Reappearing species

Cryptozoology

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

Reappearing fossil taxa

Reappearing IUCN red list species

Plants

Protostomes

Fish

Amphibians

Mammals

Reptiles

Birds

See also

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.