Қайта тірілген таксондар: Қазба жазбаларындағы үзілістер мен жаңадан табылулар

Taxon that disappears from the fossil record, only to reappear later
the music album by Tortoise

In paleontology, a Lazarus taxon (plural taxa) is a taxon that disappears for one or more periods from the fossil record, only to appear again later. Likewise in conservation biology and ecology, it can refer to species or populations that were thought to be extinct, and are rediscovered. The term Lazarus taxon was coined by Karl W. Flessa and David Jablonski in 1983 and was then expanded by Jablonski in 1986. Paul Wignall and Michael Benton defined Lazarus taxa as, "At times of biotic crisis many taxa go extinct, but others only temporarily disappeared from the fossil record, often for intervals measured in millions of years, before reappearing unchanged". Earlier work also supports the concept though without using the name Lazarus taxon, like work by Christopher R. C. Paul. The term refers to the story in the Christian biblical Gospel of John, in which Jesus Christ 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. The fossil record is inherently sporadic (only a very small fraction of organisms become fossilized, and an even smaller fraction are discovered before destruction) and contains gaps not necessarily caused by extinction, particularly when the number of individuals in a taxon is very low. After mass extinctions, such as the Permian–Triassic extinction event, the Lazarus effect occurred for many taxa. However, there appears to be no link with the abundance of fossiliferous sites and the proportion of Lazarus taxa, and no missing taxa have been found in potential refuges. Therefore, reappearance of Lazarus taxa probably reflects the rebound after a period of extreme rarity during the aftermath of such extinctions.

An Elvis taxon is a look alike that has supplanted an extinct taxon through convergent evolution. A zombie taxon is a taxon that contains specimens that have been collected from strata younger than the extinction of the taxon. Later such fossils turn out to be freed from the original seam and refossilized in a younger sediment. For example, a trilobite that gets eroded out of its Cambrian aged limestone matrix, and reworked into Miocene aged siltstone. A living fossil is an extant taxon that appears to have changed so little compared with fossil remains, that it is considered identical. Living fossils may occur regularly in the fossil record, such as the lampshell Lingula, though the living species in this genus are not identical to fossil brachiopods. Other living fossils however are also Lazarus taxa if these have been missing from the fossil record for substantial periods of time, such as applies for coelacanths. Finally, the term "Lazarus species" is applied to organisms that have been rediscovered as being still alive after having been widely considered extinct for years, without ever having appeared in the fossil record. In this last case, the term Lazarus taxon is applied in neontology.

Bush dog (Speothos venaticus), last surviving species of the genus Speothos; first described as an extinct taxon in 1842 by Peter Wilhelm Lund, based on fossils uncovered from Brazilian caves; Lund found and described living specimens in 1843 without realizing they were of the same species as the fossils, dubbing the living bush dogs as members of the genus "Icticyon"; this was not corrected until some time in the 20th century. Chacoan peccary (Catagonus wagneri), last surviving species of the genus Catagonus; believed to be the closest living relative to the extinct genus Platygonus. First described as extinct in 1930 as fossils; live specimens found in 1974. False killer whale, first described by the British paleontologist and biologist Richard Owen based on a skull discovered in 1843 found in Stamford, Lincolnshire in England and dated to the Middle Pleistocene around 126,000 years ago. The first carcasses washed up on the shores of Kiel Bay in Denmark in 1861; until this point the species was thought to be extinct. Bulmer's fruit bat (Aproteles bulmerae), originally described from a Pleistocene garbage pile, it was subsequently discovered alive elsewhere in its native New Guinea. The arboreal chinchilla rats (Cuscomys spp. ), which were originally described based on a single species (Cuscomys oblativus) known only from archaeological remains discovered in ancient Inca tombs described in 1912 and believed to be extinct for almost a century. A second species (Cuscomys ashaninka) was discovered alive in Peru in 1999, and photographs taken at Machu Picchu in 2009 suggest that C. oblativus is still alive as well. Majorcan midwife toad (Alytes muletensis), in the family Alytidae, described from fossil remains in 1977, discovered alive in 1979. Cymatioa cookae, a small bivalve mollusk of family Galeommatidae; originally documented in 1937 from Pleistocene fossil specimens near Los Angeles, then living specimens discovered in 2018 on the coast of Santa Barbara. Mountain pygmy possum (Burramys parvus), first discovered in the fossil record in 1895; rediscovered alive in 1966. Calliostoma bullatum, a species of deepwater sea snail; originally described in 1844 from fossil specimens in deep water coral related sediments from southern Italy, until extant individuals were described in 2019 from deep water coral reefs off the coast of Mauritania.

Nightcap oak (Eidothea hardeniana and Eidothea zoexylocarya), representing a genus previously known only from fossils 15 to 20 million years old, were recognized in 2000 and 1995, respectively. Gracilidris, a genus of dolichoderine ants thought to have gone extinct 15–20 million years ago was found in Paraguay, Brazil, and Argentina and redescribed in 2006. 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), sole surviving member of the order Microbiotheria; first described in 1894, thought to have gone extinct 11 million years ago. Submyotodon, a genus of bat originally known from a single fossil species (S. petersbuchensis) described in 2003 from the Miocene of Germany, about 11 to 16 million years ago. In 2015, a phylogenetic analysis of bats from Taiwan and China found three species previously classified in Myotis (M. caliginosus, M. latirostris, and M. moupinensis) to be wholly distinct from any other member of Myotis, and instead more closely allied to the fossil Submyotodon, and thus reclassified them in Submyotodon, making the genus extant once more. Dawn redwood (Metasequoia), a genus of conifer, described as a fossil in 1941, rediscovered alive in 1944. Wollemi pine (Wollemia), a genus of coniferous tree in the family Araucariaceae; previously known only from fossils from 2 to 90 million years ago, rediscovered in 1994.

Coelacanth (Latimeria), a member of a subclass (Actinistia) thought to have gone extinct 66 million years ago; live specimens found in 1938. Alavesia, a genus of Atelestid fly, originally discovered as a fossil in amber over 100 million years old in 1999, living species found in Namibia in 2010.

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.

Schinderhannes bartelsi, an extinct Devonian member of the order Radiodonta. The discovery of its fossils in Devonian was astonishing because previously, radiodonts were known only from the Cambrian, 100 million years earlier.

Judean date palm, found as a seed dated from between 155 BC to 64 AD, replanted in 2005. Montreal melon, a common plant in the 19th century that disappeared, but was rediscovered after a couple of generations in 1996.

Neptune's Cup (Cliona patera), a species of demosponge in the family Clionaidae; thought to be extinct from overharvesting in 1908, rediscovered in 2011.

Giant Palouse earthworm (Driloleirus americanus), a species of earthworm belonging to the genus Driloleirus; thought extinct in the 1980s, but found again in 2006.

Lord Howe Island stick insect (Dryococelus australis); a species of stick insect in the family Phasmatodae; thought to be extinct by 1920, rediscovered in 2001. Canterbury knobbed weevil (Hadramphus tuberculatus), in the family Curculionidae; first discovered in 1877, last seen in 1922 until it was rediscovered in 2004. The cloaked bee (Pharohylaeus lactiferus); a bee in the subfamily Hylaeinae which had not been found since 1923 and was rediscovered in 2018. Lestes patricia, a species of damselfly discovered in 1924. Only a single male specimen was collected during the discovery. The species was left unseen until 2020 where a colony of them was rediscovered. Megachile pluto, the world's largest bee. Not seen after 1858, when it was first collected, until it was rediscovered in 1981. Dinosaur ant (Nothomyrmecia macrops), a rare genus of ants consisting of a single species, discovered in 1931, not seen again until 1977. Petasida ephippigera, a species of grasshopper in the family Pyrgomorphidae; thought to be extinct from 1900 until 1971, when a single male specimen was spotted, followed by a breeding pair shortly afterwards. Schizodactylus inexspectatus, a dune inhabiting cricket from Turkey, known from a single specimen seen in 1901 and presumed extinct until it was found again in 2005. Bone skipper fly (Thyreophora cynophila), in the family Piophilidae; first described (1794) and last seen in Central Europe (1850), before being photographed in Spain in 2009. Pitt Island longhorn beetle (Xylotoles costatus), is a species of beetle in the family Cerambycidae; last seen on Pitt Island in 1910, and found again on a nearby island in the Chatham Islands in 1987.

Batman River Loach, a loach species not seen since 1970s. Rediscovered in 2021. Black kokanee (Oncorhynchus nerka kawamurae), a Japanese species of salmon in the family Salmonidae; believed extinct in 1940 after attempts at conservation seemingly failed. The species was rediscovered in Lake Saiko in 2010, having survived after prior conservation efforts had introduced it there.

Because its definition is ambiguous, some, like R. B. Rickards and A. J. Wright, reject the very concept of the Lazarus taxon. Rickards and Wright have questioned the usefulness of the concept, writing in "Lazarus taxa, refugia and relict faunas: evidence from graptolites" that anyone could argue that any gap in the fossil record could potentially be considered a Lazarus effect because the duration required for the Lazarus effect is not defined. They have argued that accurate plotting of biodiversity changes and species abundance through time, coupled with an appraisal of their palaeobiogeography, is more important than using this title to categorize species. One conservation outreach project that has focused exclusively on species rediscoveries is the Lost & Found project which aims to tell the stories of species once thought extinct but that were subsequently rediscovered.