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 either in later fossil records, or as actual living organisms, and often in isolated, obscure, or otherwise very specialized habitats. Likewise in conservation biology and ecology, it can refer to species or populations that were mistakenly thought to be extinct, and are rediscovered to be still living. 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.
Potential explanations 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.
Related but distinct concepts
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 ghost lineage is a pronounced gap in time for the fossil record of a group, indicating that the group continued evolving throughout the gap, without direct fossil evidence from within the gap. Lazarus taxa are a type of ghost lineage where extinction was originally assumed to occur within the gap, only for younger fossils or surviving members of the group to indicate otherwise.
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.
In paleovirology, divergent clades of genomic elements from presumably extinct viruses are often known only from host genomes. However, in some cases extant viruses have later been associated with these "fossil" elements, indicating Lazarus-like taxa. For example, a clade of paleoviruses from presumed extinct filoviruses found in shrews was later found to contain an extant filovirus (Tapajós virus, TAPV).
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.
Reappearing fossil taxa From Quaternary (2.6 to 0 million years ago)
Two possum species, ring-tailed glider (Tous ayamaruensis) and pygmy long-fingered possum (Dactylonax kambuayai); originally described entirely based on fossils in the 1990s, were rediscovered in 2026 still alive by a collaboration of scientists, indigenous communities, and citizen scientists. 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.. Ben G Thomas. 25 February 2018; 0:32 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 (Pseudorca crassidens), 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.
From Neogene (23 to 2.6 million years ago)
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. Cuvier's beaked whale (Ziphius cavirostris), first described by French naturalist and zoologist Georges Cuvier based on a skull collected on the Mediterranean coast of France at Fos-sur-mer, Bouches-du-Rhône, in 1804. He believed this represented the remains of an extinct species. Later in 1850, paleontologist and zoologist Paul Geravis found the skull to be identical to that of a stranded whale carcass he had just examined. 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 gliroides), 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.
From Paleogene (66 to 23 million years ago)
Archaeidae, a family of spiders found in Madagascar, South Africa, and Australia, originally described from amber found in Europe, dating to the Eocene in the 1840. In 1881, the first living pelican spiders were discovered in Madagascar, and in 2003, Afarchaea grimaldii was described from Cretaceous Burmese amber aged between 88 and 95 million years. Lignobrycon, a characiform fish from southern Brazil, was originally described from well-preserved fossil remains from the late Oligocene in 1929. In 1998, the extant fish "Moojenichthys" myersi, described in 1956, was identified as belonging to the same genus as the fossil Lignobrycon. Juliidae, a family of small sea snails known only from Eocene fossil shells, and not surprisingly, these fossils were interpreted as being the shells of bivalves. Until the mid-20th century, these creatures were still considered to be bivalves. Then, in 1959, living individuals of one species were collected on the green alga, Caulerpa, in Japan. It was immediately clear that these animals were, in fact, unusual gastropods with a two-part shell. The first-discovered live species of bivalved gastropod was Tamanovalva limax, described by Kawaguti & Baba (1959). Once the habitat, appearance, and life habits of these very small and inconspicuous animals were understood, researchers in subsequent years were able to find a number of other species and genera in different parts of the world, also living on various species of Caulerpa.
From Cretaceous (145 to 66 million years ago)
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.
From Permian (299 to 252 million years ago)
Pozabudnutie, a genus of cockroach recorded from both late Permian sediments in Siberia and mid-Cretaceous Burmese amber
From Devonian (419 to 359 million years ago)
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.
From Cambrian (539 to 485 million years ago) 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. It was discovered that the living genus Rhabdopleura is an extant graptolite, which was previously known from the Middle Cambrian through the Lower Carboniferous.
Reappearing IUCN red list species
Plants Afrothismia pachyantha, in the family Burmanniaceae; first discovered in 1905, rediscovered in 1995. Ascension Island parsley fern (Anogramma ascensionis), last collected in 1958 and declared extinct in 2003, rediscovered in 2010. Asplundia clementinae, a species of plant in the family Cyclanthaceae. Astragalus nitidiflorus, rediscovered in 2004 after 100 years.