A living fossil is an

extant taxon Neontology is a part of biology that, in contrast to paleontology, deals with living (or, more generally, '' recent'') organisms. It is the study of extant taxa (singular: extant taxon): taxa (such as species, genera and families) with member ...

that cosmetically resembles related species known only from the fossil record. To be considered a living fossil, the fossil species must be old relative to the time of origin of the extant

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English ter ...

. Living fossils commonly are of species-poor lineages, but they need not be. While the body plan of a living fossil remains superficially similar, it is never the same species as the remote relatives it resembles, because genetic drift would inevitably change its chromosomal structure. Living fossils exhibit

stasis Stasis (from Greek στάσις "a standing still") may refer to: * A state in stability theory, in which all forces are equal and opposing, therefore they cancel out each other * Stasis (political history), a period of civil war within an ancient ...

(also called "bradytely") over geologically long time scales. Popular literature may wrongly claim that a "living fossil" has undergone no significant evolution since fossil times, with practically no

molecular evolution Molecular evolution is the process of change in the sequence composition of cellular molecules such as DNA, RNA, and proteins across generations. The field of molecular evolution uses principles of evolutionary biology and population genet ...

or morphological changes. Scientific investigations have repeatedly discredited such claims. The minimal superficial changes to living fossils are mistakenly declared as an absence of evolution, but they are examples of stabilizing selection, which is an evolutionary process—and perhaps the dominant process of morphological evolution.

Characteristics

Living fossils have two main characteristics, although some have a third: # Living organisms that are members of a

taxon In biology, a taxon ( back-formation from '' taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular n ...

that has remained recognisable in the fossil record over an unusually long time span. # They show little morphological divergence, whether from early members of the lineage, or among

extant species Neontology is a part of biology that, in contrast to paleontology, deals with living (or, more generally, ''recent'') organisms. It is the study of extant taxa (singular: extant taxon): taxa (such as species, genera and families) with members sti ...

. # They tend to have little taxonomic diversity. The first two are required for recognition as a ''living fossil'' status; some authors also require the third, others merely note it as a frequent trait. Such criteria are neither well-defined nor clearly quantifiable, but modern methods for analyzing evolutionary dynamics can document the distinctive tempo of stasis. Lineages that exhibit stasis over very short time scales are not considered living fossils; what is poorly-defined is the time scale over which the morphology must persist for that lineage to be recognized as a living fossil. The term "living fossil" is much misunderstood in popular media in particular, in which it often is used meaninglessly. In professional literature the expression seldom appears and must be used with far more caution, although it has been used inconsistently. One example of a concept that could be confused with "living fossil" is that of a "

Lazarus taxon 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 tha ...

", but the two are not equivalent; a Lazarus taxon (whether a single species or a group of related species) is one that suddenly reappears, either in the fossil record or in nature, as if the fossil had "come to life again". In contrast to "Lazarus taxa", a living fossil in most senses is a species or lineage that has undergone exceptionally little change throughout a long fossil record, giving the impression that the extant taxon had remained identical through the entire fossil and modern period. Because of the mathematical inevitability of genetic drift, though, the DNA of the modern species is necessarily different from that of its distant, similar-looking ancestor. They almost certainly would not be able to cross-reproduce, and are not the same species. The average species turnover time, meaning the time between when a species first is established and when it finally disappears, varies widely among

phyla Phyla, the plural of ''phylum'', may refer to: * Phylum, a biological taxon between Kingdom and Class * by analogy, in linguistics, a large division of possibly related languages, or a major language family which is not subordinate to another Phy ...

, but averages about 2–3 million years. A living taxon that had long been thought to be extinct could be called a Lazarus taxon once it was discovered to be still extant. A dramatic example was the order

Coelacanthiformes The coelacanths ( ) are fish belonging to the order Actinistia that includes two extant species in the genus ''Latimeria'': the West Indian Ocean coelacanth (''Latimeria chalumnae''), primarily found near the Comoro Islands off the east coast ...

, of which the genus ''

Latimeria ''Latimeria'' is a rare genus of fish which contains the only living species of coelacanth. It includes two extant species: the West Indian Ocean coelacanth (''Latimeria chalumnae'') and the Indonesian coelacanth (''Latimeria menadoensis''). T ...

'' was found to be extant in 1938. About that there is little debate — however, whether ''Latimeria'' resembles early members of its lineage sufficiently closely to be considered a living fossil as well as a Lazarus taxon has been denied by some authors in recent years. Coelacanths disappeared from the fossil record some 80 million years ago (upper

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

) and, to the extent that they exhibit low rates of morphological evolution, extant species qualify as living fossils. It must be emphasised that this criterion reflects fossil evidence, and is totally independent of whether the taxa had been subject to selection at all, which all living populations continuously are, whether they remain genetically unchanged or not. This apparent stasis, in turn, gives rise to a great deal of confusion — for one thing, the fossil record seldom preserves much more than the general morphology of a specimen. To determine much about its physiology is seldom possible; not even the most dramatic examples of living fossils can be expected to be without changes, no matter how persistently constant their fossils and the extant specimens might seem. To determine much about

noncoding DNA Non-coding DNA (ncDNA) sequences are components of an organism's DNA that do not encode protein sequences. Some non-coding DNA is transcribed into functional non-coding RNA molecules (e.g. transfer RNA, microRNA, piRNA, ribosomal RNA, and r ...

is hardly ever possible, but even if a species were hypothetically unchanged in its physiology, it is to be expected from the very nature of the reproductive processes, that its non-functional

genomic Genomics is an interdisciplinary field of biology focusing on the structure, function, evolution, mapping, and editing of genomes. A genome is an organism's complete set of DNA, including all of its genes as well as its hierarchical, three-dim ...

changes would continue at more-or-less standard rates. Hence, a fossil lineage with apparently constant ''morphology'' need not imply equally constant ''physiology'', and certainly neither implies any cessation of the basic evolutionary processes such as natural selection, nor reduction in the usual rate of change of the noncoding DNA. Some living fossils are taxa that were known from palaeontological fossils before living representatives were discovered. The most famous examples of this are: *

Coelacanth The coelacanths ( ) are fish belonging to the order Actinistia that includes two extant species in the genus ''Latimeria'': the West Indian Ocean coelacanth (''Latimeria chalumnae''), primarily found near the Comoro Islands off the east coast ...

iform fishes (2 species) * ''Metasequoia'', the

dawn redwood ''Metasequoia glyptostroboides'', the dawn redwood, is a fast-growing, endangered deciduous conifer. It is the sole living species of the genus ''Metasequoia'', one of three genera in the subfamily Sequoioideae of the family Cupressaceae. It now ...

discovered in a remote Chinese valley (1 species) * glypheoid lobsters (2 species) * mymarommatid wasps (10 species) * eomeropid scorpionflies (1 species) * jurodid beetles (1 species) * soft sea urchins (59 species) All the above include taxa that originally were described as fossils but now are known to include still-extant species. Other examples of living fossils are single living species that have no close living relatives, but are survivors of large and widespread groups in the fossil record. For example: * ''

Ginkgo biloba ''Ginkgo biloba'', commonly known as ginkgo or gingko ( ), also known as the maidenhair tree, is a species of tree native to China. It is the last living species in the order Ginkgoales, which first appeared over 290 million years ago. Fossils ...

'' * ''

Syntexis libocedrii ''Syntexis libocedrii'', (also called the cedar wood wasp or incense-cedar wood wasp) is the only living species in the wood wasp family Anaxyelidae, within the Symphyta, though the family has an extensive Mesozoic fossil record. This species i ...

'', the cedar wood wasp *

Dinoflagellates The dinoflagellates ( Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates ...

(typified on coccoid

dinocysts Dinocysts or dinoflagellate cysts are typically 15 to 100 µm in diameter and produced by around 15–20% of living dinoflagellates as a dormant, zygotic stage of their lifecycle, which can accumulate in the sediments as microfossils. Organic- ...

: occasionally calcareous cell remnants) All of these were described from fossils before later being found alive. The fact that a living fossil is a surviving representative of an archaic lineage does not imply that it must retain all the "primitive" features ( plesiomorphies) of its ancestral lineage. Although it is common to say that living fossils exhibit "morphological stasis", stasis, in the scientific literature, does not mean that any species is strictly identical to its ancestor, much less remote ancestors. Some living fossils are relicts of formerly diverse and morphologically varied lineages, but not all survivors of ancient lineages necessarily are regarded as living fossils. See for example the uniquely and highly autapomorphic oxpeckers, which appear to be the only survivors of an ancient lineage related to

starling Starlings are small to medium-sized passerine birds in the family Sturnidae. The Sturnidae are named for the genus '' Sturnus'', which in turn comes from the Latin word for starling, ''sturnus''. Many Asian species, particularly the larger ones, ...

s and mockingbirds.

Evolution and living fossils

The term ''living fossil'' is usually reserved for species or larger clades that are exceptional for their lack of morphological diversity and their exceptional conservatism, and several hypotheses could explain morphological stasis on a geologically long time-scale. Early analyses of evolutionary rates emphasized the persistence of a taxon rather than rates of evolutionary change. Contemporary studies instead analyze rates and modes of phenotypic evolution, but most have focused on clades that are thought to be adaptive radiations rather than on those thought to be living fossils. Thus, very little is presently known about the evolutionary mechanisms that produce living fossils or how common they might be. Some recent studies have documented exceptionally low rates of ecological and phenotypic evolution despite rapid speciation. This has been termed a "non-adaptive radiation" referring to diversification not accompanied by adaptation into various significantly different niches. Such radiations are explanation for groups that are morphologically conservative. Persistent adaptation within an adaptive zone is a common explanation for morphological stasis. The subject of very low evolutionary rates, however, has received much less attention in the recent literature than that of high rates Living fossils are not expected to exhibit exceptionally low rates of molecular evolution, and some studies have shown that they do not. For example, on tadpole shrimp (''

Triops ''Triops'' is a genus of small crustaceans in the order Notostraca (tadpole shrimp). The long-lasting resting eggs of several species of ''Triops'' are commonly sold in kits as a pet. The animals hatch upon contact with fresh water. Most adult-st ...

''), one article notes, "Our work shows that organisms with conservative body plans are constantly radiating, and presumably, adapting to novel conditions.... I would favor retiring the term ‘living fossil’ altogether, as it is generally misleading." Some scientists instead prefer a new term stabilomorph, being defined as "an effect of a specific formula of adaptative strategy among organisms whose taxonomic status does not exceed genus-level. A high effectiveness of adaptation significantly reduces the need for differentiated phenotypic variants in response to environmental changes and provides for long-term evolutionary success." The question posed by several recent studies pointed out that the morphological conservatism of coelacanths is not supported by paleontological data. In addition, it was shown recently that studies concluding that a slow rate of molecular evolution is linked to morphological conservatism in coelacanths are biased by the ''

a priori ("from the earlier") and ("from the later") are Latin phrases used in philosophy to distinguish types of knowledge, justification, or argument by their reliance on empirical evidence or experience. knowledge is independent from current ex ...

'' hypothesis that these species are ‘living fossils’. Accordingly, the genome stasis hypothesis is challenged by the recent finding that the genome of the two extant coelacanth species ''L. chalumnae'' and ''L. menadoensis'' contain multiple species-specific insertions, indicating transposable element recent activity and contribution to post-speciation genome divergence. Such studies, however, challenge only a genome stasis hypothesis, not the hypothesis of exceptionally low rates of phenotypic evolution.

History

The term was coined by

Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended ...

in his ''

On the Origin of Species ''On the Origin of Species'' (or, more completely, ''On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life''),The book's full original title was ''On the Origin of Species by Me ...

'' from 1859, when discussing ''

Ornithorhynchus The platypus (''Ornithorhynchus anatinus''), sometimes referred to as the duck-billed platypus, is a semiaquatic, egg-laying mammal endemic to eastern Australia, including Tasmania. The platypus is the sole living representative or monotypi ...

'' (the platypus) and ''

Lepidosiren The South American lungfish (''Lepidosiren paradoxa'') is the single species of lungfish found in swamps and slow-moving waters of the Amazon, Paraguay, and lower Paraná River basins in South America. Notable as an obligate air-breather, it is t ...

'' (the South American lungfish):

Other definitions

Long-enduring

A living taxon that lived through a large portion of

geologic time The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochro ...

. The

Australian lungfish The Australian lungfish (''Neoceratodus forsteri''), also known as the Queensland lungfish, Burnett salmon and barramunda, is the only surviving member of the family Neoceratodontidae. It is one of only six extant lungfish species in the world. ...

(''Neoceratodus fosteri''), also known as the Queensland lungfish, is an example of an organism that meets this criterion. Fossils identical to modern specimens have been dated at over 100 million years old. Modern Queensland lungfish have existed as a species for almost 30 million years. The contemporary

nurse shark The nurse shark (''Ginglymostoma cirratum'') is an elasmobranch fish in the family Ginglymostomatidae. The conservation status of the nurse shark is globally assessed as Vulnerable in the IUCN List of Threatened Species. They are considered t ...

has existed for more than 112 million years, making this species one of the oldest, if not actually the oldest extant vertebrate species.

Resembles ancient species

A living taxon morphologically and/or

physiologically Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical a ...

resembling a fossil taxon through a large portion of geologic time (morphological stasis).

Retains many ancient traits

A living taxon with many characteristics believed to be primitive. This is a more neutral definition. However, it does not make it clear whether the taxon is truly old, or it simply has many plesiomorphies. Note that, as mentioned above, the converse may hold for true living fossil taxa; that is, they may possess a great many derived features (

autapomorphies In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to t ...

), and not be particularly "primitive" in appearance.

Relict population

Any one of the above three definitions, but also with a

relict distribution In biogeography and paleontology, a relict is a population or taxon of organisms that was more widespread or more diverse in the past. A relictual population is a population currently inhabiting a restricted area whose Range (biology), range was fa ...

in refuges. Some paleontologists believe that living fossils with large distributions (such as ''

Triops cancriformis ''Triops cancriformis'', European tadpole shrimp or tadpole shrimp, is a species of tadpole shrimp found in Europe to the Middle East and India. Due to habitat destruction, many populations have recently been lost across its European range, ...

'') are not real living fossils. In the case of ''Triops cancriformis'' (living from the

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest per ...

until now), the Triassic specimens lost most of their appendages (mostly only

carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...

s remain), and they have not been thoroughly examined since 1938.

Low diversity

Any of the first three definitions, but the

also has a low taxonomic diversity (low diversity lineages). Oxpeckers are morphologically somewhat similar to

starlings Starlings are small to medium-sized passerine birds in the family Sturnidae. The Sturnidae are named for the genus '' Sturnus'', which in turn comes from the Latin word for starling, ''sturnus''. Many Asian species, particularly the larger ones, ...

due to shared plesiomorphies, but are uniquely adapted to feed on parasites and blood of large land mammals, which has always obscured their relationships. This lineage forms part of a radiation that includes Sturnidae and Mimidae, but appears to be the most ancient of these groups.

Biogeography Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, ...

strongly suggests that oxpeckers originated in eastern

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...

and only later arrived in Africa, where they now have a relict distribution. The two living species thus seem to represent an entirely extinct and (as

Passerida Passerida is, under the Sibley-Ahlquist taxonomy, one of two parvorders contained within the suborder Passeri (standard taxonomic practice would place them at the rank of infraorder). While more recent research suggests that its sister parvorde ...

go) rather ancient lineage, as certainly as this can be said in the absence of actual fossils. The latter is probably due to the fact that the oxpecker lineage never occurred in areas where conditions were good for fossilization of small bird bones, but of course, fossils of ancestral oxpeckers may one day turn up enabling this theory to be tested.

Operational definition

An operational definition was proposed in 2017, where a 'living fossil' lineage has a slow rate of evolution and occurs close to the middle of morphological variation (the centroid of morphospace) among related taxa (i.e. a species is morphologically conservative among relatives). The scientific accuracy of the

morphometric Morphometrics (from Greek μορϕή ''morphe'', "shape, form", and -μετρία ''metria'', "measurement") or morphometry refers to the quantitative analysis of ''form'', a concept that encompasses size and shape. Morphometric analyses are c ...

analyses used to classify tuatara as a living fossil under this definition have been criticised however, which prompted a rebuttal from the original authors.

Examples

Some of these are informally known as "living fossils". Ginkgo Stamm

Bacteria

Cyanobacteria Cyanobacteria (), also known as Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color (), which similarly forms the basis of cyanobacteria's common name, bl ...

- the oldest living fossils, emerging 3.5 billion years ago. They exist as single bacteria but are most often pictured as

stromatolite Stromatolites () or stromatoliths () are layered sedimentary formations ( microbialite) that are created mainly by photosynthetic microorganisms such as cyanobacteria, sulfate-reducing bacteria, and Pseudomonadota (formerly proteobacteria). T ...

s, artificial rocks produced by cyanobacteria waste.

Protists

* The

dinoflagellate The dinoflagellates ( Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are ...

†''Calciodinellum operosum''. * The

†''Dapsilidinium pastielsii''. * The

†''Posoniella tricarinelloides''. * The

coccolithophore Coccolithophores, or coccolithophorids, are single celled organisms which are part of the phytoplankton, the autotrophic (self-feeding) component of the plankton community. They form a group of about 200 species, and belong either to the king ...

''Tergestiella adriatica''.

Plants

Moss Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) '' sensu stricto''. Bryophyta ('' sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and ...

Pteridophytes A pteridophyte is a vascular plant (with xylem and phloem) that disperses spores. Because pteridophytes produce neither flowers nor seeds, they are sometimes referred to as "cryptogams", meaning that their means of reproduction is hidden. Ferns, ...

Horsetail ''Equisetum'' (; horsetail, snake grass, puzzlegrass) is the only living genus in Equisetaceae, a family of ferns, which reproduce by spores rather than seeds. ''Equisetum'' is a "living fossil", the only living genus of the entire subclass ...

s – ''Equisetum'' **

Lycopods Lycopodiopsida is a class of vascular plants known as lycopods, lycophytes or other terms including the component lyco-. Members of the class are also called clubmosses, firmosses, spikemosses and quillworts. They have dichotomously branching s ...

** Tree ferns and

ferns A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes except th ...

Gymnosperm The gymnosperms ( lit. revealed seeds) are a group of seed-producing plants that includes conifers, cycads, '' Ginkgo'', and gnetophytes, forming the clade Gymnospermae. The term ''gymnosperm'' comes from the composite word in el, γυμν ...

s **

Conifers Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All ext ...

***''

Agathis ''Agathis'', commonly known as kauri or dammara, is a genus of 22 species of evergreen tree. The genus is part of the ancient conifer family Araucariaceae, a group once widespread during the Jurassic and Cretaceous periods, but now largely re ...

'' – kauri in New Zealand, Australia and the Pacific and almasiga in the Philippines *** ''

Araucaria araucana ''Araucaria araucana'' (commonly called the monkey puzzle tree, monkey tail tree, piñonero, pewen or Chilean pine) is an evergreen tree growing to a trunk diameter of 1–1.5 m (3–5 ft) and a height of 30–40 m (100–130 ft). ...

'' – the monkey puzzle tree (as well as other extant ''

Araucaria ''Araucaria'' (; original pronunciation: .ɾawˈka. ɾja is a genus of evergreen coniferous trees in the family Araucariaceae. There are 20 extant species in New Caledonia (where 14 species are endemic, see New Caledonian ''Araucaria ...

'' species) *** ''

Metasequoia ''Metasequoia'', or dawn redwoods, is a genus of fast-growing deciduous trees, one of three species of conifers known as redwoods. The living species ''Metasequoia glyptostroboides'' is native to Lichuan county in Hubei province, China. Althou ...

'' – dawn redwood (Cupressaceae; related to '' Sequoia'' and ''

Sequoiadendron ''Sequoiadendron'' is a genus of evergreen trees, with two species, only one of which survives to the present: * ''Sequoiadendron giganteum'', extant, commonly known as wellingtonia, giant redwood and giant sequoia, growing naturally in the Sierr ...

'') *** '' Sciadopitys'' – a unique conifer endemic to Japan known in the fossil record for about 230 million years. *** ''

Taiwania cryptomerioides ''Taiwania'', with the single living species ''Taiwania cryptomerioides'', is a large coniferous tree in the cypress family Cupressaceae. Etymology ''Taiwania'' means 'from Taiwan', while ''Cryptomerioides'' means 'resembling ''Cryptomeria''.Gle ...

'' – one of the largest tree species in Asia. *** '' Wollemia'' tree (''

Araucariaceae Araucariaceae – also known as araucarians – is an extremely ancient family of coniferous trees. The family achieved its maximum diversity during the Jurassic and Cretaceous periods and the early Cenozoic, when it was distributed almost worldw ...

'' – a borderline example, related to ''

'' and ''

'') **

Cycad Cycads are seed plants that typically have a stout and woody (ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male o ...

s ** ''

Ginkgo ''Ginkgo'' is a genus of non-flowering seed plants. The scientific name is also used as the English name. The order to which it belongs, Ginkgoales, first appeared in the Permian, 270 million years ago, and is now the only living genus with ...

'' tree (Ginkgoaceae) ** ''

Welwitschia ''Welwitschia'' is a monotypic gymnosperm genus, comprising solely the distinctive ''Welwitschia mirabilis'', endemic to the Namib desert within Namibia and Angola. ''Welwitschia'' is the only living genus of the family Welwitschiaceae and orde ...

'' *

Angiosperm Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants ...

s ** ''

Amborella ''Amborella'' is a monotypic genus of understory shrubs or small trees Endemism, endemic to the main island, Grande Terre (New Caledonia), Grande Terre, of New Caledonia in the southwest Pacific Ocean. The genus is the only member of the family ...

'' – a plant from New Caledonia, possibly closest to base of the

flowering plants Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants t ...

** '' Trapa'' - water caltrops, seeds, and leaves of numerous extinct species are known all the way back to the Cretaceous. ** ''

Nelumbo ''Nelumbo'' is a genus of aquatic plants with large, showy flowers. Members are commonly called lotus, though the name is also applied to various other plants and plant groups, including the unrelated genus '' Lotus''. Members outwardly resemb ...

'' - several species of lotus flower are known exclusively from fossils dating back to the Cretaceous.

Fungi

* ''

Neolecta ''Neolecta'' is a genus of ascomycetous fungi that have fruiting bodies in the shape of unbranched to lobed bright yellowish, orangish to pale yellow-green colored, club-shaped, smooth, fleshy columns up to about 7 cm tall. The species shar ...

Animals

;Vertebrates: Hoatzins in Ecuador

* Mammals **

Aardvark The aardvark ( ; ''Orycteropus afer'') is a medium-sized, burrowing, nocturnal mammal native to Africa. It is the only living species of the order Tubulidentata, although other prehistoric species and genera of Tubulidentata are known. Unlik ...

(''Orycteropus afer'') **

Amami rabbit The Amami rabbit (''Pentalagus furnessi''; ), or , also known as the Ryukyu rabbit is a dark-furred rabbit which is only found in Amami Ōshima and Toku-no-Shima, two small islands between southern Kyūshū and Okinawa in Kagoshima Prefecture ...

(''Pentalagus furnessi'') **

Nesolagus ''Nesolagus'' is a genus of rabbits containing three species of striped rabbit: the Annamite striped rabbit, the Sumatran striped rabbit, and the extinct species ''N. sinensis''. Overall there is very little known about the genus as a whole, mo ...

(''Asian striped rabbits'') **

Chevrotain Chevrotains, or mouse-deer, are small even-toed ungulates that make up the family Tragulidae, the only extant members of the infraorder Tragulina. The 10 extant species are placed in three genera, but several species also are known only f ...

(''Tragulidae'') ** Chousingha (''Tetracerus quadricornis'') **

Elephant shrew Elephant shrews, also called jumping shrews or sengis, are small insectivorous mammals native to Africa, belonging to the family Macroscelididae, in the order Macroscelidea. Their traditional common English name "elephant shrew" comes from a perc ...

(Macroscelidea) ** Laotian rock rat (''Laonastes aenigmamus'') **

Monito del monte The monito del monte or colocolo opossum, ''Dromiciops gliroides'', also called ''chumaihuén'' in Mapudungun, is a diminutive marsupial native only to southwestern South America (Argentina and Chile). It is the only extant species in the ancient ...

(''Dromiciops gliroides'') **

Monotreme Monotremes () are prototherian mammals of the order Monotremata. They are one of the three groups of living mammals, along with placentals ( Eutheria), and marsupials (Metatheria). Monotremes are typified by structural differences in their brai ...

s (the

platypus The platypus (''Ornithorhynchus anatinus''), sometimes referred to as the duck-billed platypus, is a semiaquatic, egg-laying mammal endemic to eastern Australia, including Tasmania. The platypus is the sole living representative or mono ...

and

echidna Echidnas (), sometimes known as spiny anteaters, are quill-covered monotremes (egg-laying mammals) belonging to the family Tachyglossidae . The four extant species of echidnas and the platypus are the only living mammals that lay eggs and the ...

) **

Mountain beaver The mountain beaver (''Aplodontia rufa'')Other names include mountain boomer, ground bear, giant mole, gehalis, lesser sasquatch, sewellel, suwellel, showhurll, showtl, and showte, as well as a number of Chinookan and other Native American terms ...

(''Aplodontia rufa'') **

Okapi The okapi (; ''Okapia johnstoni''), also known as the forest giraffe, Congolese giraffe, or zebra giraffe, is an artiodactyl mammal that is endemic to the northeast Democratic Republic of the Congo in central Africa. It is the only species ...

(''Okapia johnstoni'') **

Sumatran rhinoceros The Sumatran rhinoceros (''Dicerorhinus sumatrensis''), also known as the Sumatran rhino, hairy rhinoceros or Asian two-horned rhinoceros, is a rare member of the family Rhinocerotidae and one of five extant species of rhinoceros. It is the o ...

('' Dicerorhinus sumatrensis'') **

Opossum Opossums () are members of the marsupial order Didelphimorphia () endemic to the Americas. The largest order of marsupials in the Western Hemisphere, it comprises 93 species in 18 genera. Opossums originated in South America and entered No ...

s (''Didelphidae'') **

Clouded leopard The clouded leopard (''Neofelis nebulosa''), also called the mainland clouded leopard, is a wild cat inhabiting dense forests from the foothills of the Himalayas through mainland Southeast Asia into South China. In the early 19th century, a ...

(''Neofelis nebulousa'') **

Capybara The capybaraAlso called capivara (in Brazil), capiguara (in Bolivia), chigüire, chigüiro, or fercho (in Colombia and Venezuela), carpincho (in Argentina, Paraguay and Uruguay) and ronsoco (in Peru). or greater capybara (''Hydrochoerus hydro ...

(''Hydrochoerus hydrochaeris'') **

Bush dog The bush dog (''Speothos venaticus'') is a canine found in Central and South America. In spite of its extensive range, it is very rare in most areas except in Suriname, Guyana and Peru; it was first identified by Peter Wilhelm Lund from foss ...

(''Speothos venaticus'') **

Maned wolf The maned wolf (''Chrysocyon brachyurus'') is a large canine of South America. It is found in Argentina, Brazil, Bolivia, Peru, and Paraguay, and is almost extinct in Uruguay. Its markings resemble those of foxes, but it is neither a fox nor a w ...

(''Chrysocyon brachyurus'') **

Red panda The red panda (''Ailurus fulgens''), also known as the lesser panda, is a small mammal native to the eastern Himalayas and southwestern China. It has dense reddish-brown fur with a black belly and legs, white-lined ears, a mostly white muzzle ...

(''Ailurus fulgens'') **

Solenodon Solenodons (from el, τέλειος , 'channel' or 'pipe' and el, ὀδούς , 'tooth') are venomous, nocturnal, burrowing, insectivorous mammals belonging to the family Solenodontidae . The two living solenodon species are the Cuban solen ...

('' Solenodon cubanus'' and '' Solenodon paradoxus'') ** Shrew opossum (''Caenolestidae'') ** Spectacled bear (''Tremarctos ornatus'') ** False killer whale (''Pseudorca crassidens'') **

Pygmy right whale The pygmy right whale (''Caperea marginata'') is a species of baleen whale. It may be a member of the cetotheres, a family of baleen whales which until 2012 were thought to be extinct; ''C. marginata'' has otherwise been considered the monotyp ...

(''Caperea marginata'') **

Pacarana The pacarana (''Dinomys branickii'') is a rare and slow-moving hystricognath rodent indigenous to South America. Native Tupi people call it the ''pacarana'' (false paca) because it is superficially similar to the paca, a different rodent which is ...

(''Dinomys branickii'') * Birds **

Pelican Pelicans (genus ''Pelecanus'') are a genus of large water birds that make up the family Pelecanidae. They are characterized by a long beak and a large throat pouch used for catching prey and draining water from the scooped-up contents before ...

s (''Pelecanus'') –

form Form is the shape, visual appearance, or configuration of an object. In a wider sense, the form is the way something happens. Form also refers to: *Form (document), a document (printed or electronic) with spaces in which to write or enter data * ...

has been virtually unchanged since the

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', ...

, and is noted to have been even more conserved across the Cenozoic than that of crocodiles. ** Acanthisittidae (New Zealand "wrens") – 2 living species, a few more recently

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

. Distinct lineage of

Passeriformes A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped'), which includes more than half of all bird species. Sometimes known as perching birds, passerines are distinguished from other orders of birds by th ...

. ** Broad-billed sapayoa (''Sapayoa aenigma'') – One living species. Distinct lineage of

Tyranni The Tyranni (suboscines) are a suborder of passerine birds that includes more than 1,000 species, the large majority of which are South American. It is named after the type genus ''Tyrannus''. These have a different anatomy of the syrinx m ...

. **

Bearded reedling The bearded reedling (''Panurus biarmicus'') is a small, sexually dimorphic reed-bed passerine bird. It is frequently known as the bearded tit, due to some similarities to the long-tailed tit, or the bearded parrotbill. It is the only species ...

(''Panurus biarmicus'') – One living species. Distinct lineage of

Sylvioidea Sylvioidea is a superfamily of passerine birds, one of at least three major clades within the Passerida along with the Muscicapoidea and Passeroidea. It contains about 1300 species including the Old World warblers, Old World babblers, swallows ...

. **

Picathartes The picathartes, rockfowl, or bald crows are a small genus of two passerine bird species forming the family Picathartidae found in the rain-forests of tropical west and central Africa. They have unfeathered heads, and feed on insects and inverte ...

(rockfowls) ** Coliiformes (mousebirds) – 6 living species in 2 genera. Distinct lineage of

Neoaves Neoaves is a clade that consists of all modern birds (Neornithes or Aves) with the exception of Paleognathae (ratites and kin) and Galloanserae (ducks, chickens and kin). Almost 95% of the roughly 10,000 known species of extant birds belong to ...

. **

Hoatzin The hoatzin ( ) or hoactzin ( ), (''Opisthocomus hoazin''), is the only species in the order Opisthocomiformes. It is a species of tropical bird found in swamps, riparian forests, and mangroves of the Amazon and the Orinoco basins in South Ameri ...

(''Ophisthocomus hoazin'') – One living species. Distinct lineage of

. **

Magpie goose The magpie goose (''Anseranas semipalmata'') is the sole living representative species of the family Anseranatidae. This common waterbird is found in northern Australia and southern New Guinea. As the species is prone to wandering, especially w ...

(''Anseranas semipalmata'') – One living species. Distinct lineage of

Anseriformes Anseriformes is an order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest family, which in ...

. ** Seriema (''Cariamidae'') – 2 living species. Distinct lineage of Cariamae. ** Tinamiformes (tinamous) 50 living species. Distinct lineage of

Palaeognathae Palaeognathae (; ) is a infraclass of birds, called paleognaths, within the class Aves of the clade Archosauria. It is one of the two extant infraclasses of birds, the other being Neognathae, both of which form Neornithes. Palaeognathae conta ...

. * Reptiles **

Crocodilia Crocodilia (or Crocodylia, both ) is an order of mostly large, predatory, semiaquatic reptiles, known as crocodilians. They first appeared 95 million years ago in the Late Cretaceous period ( Cenomanian stage) and are the closest livi ...

(

crocodile Crocodiles (family Crocodylidae) or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term crocodile is sometimes used even more loosely to include all extant me ...

s, gavials,

caiman A caiman (also cayman as a variant spelling) is an alligatorid belonging to the subfamily Caimaninae, one of two primary lineages within the Alligatoridae family, the other being alligators. Caimans inhabit Mexico, Central and South America f ...

s and

alligator An alligator is a large reptile in the Crocodilia order in the genus ''Alligator'' of the family Alligatoridae. The two extant species are the American alligator (''A. mississippiensis'') and the Chinese alligator (''A. sinensis''). Additional ...

s) ** Pig-nosed turtle (''Carettochelys insculpta'') ** Hickatee (''Dermatemys mawii'') **

Snapping turtle The Chelydridae is a family of turtles that has seven extinct and two extant genera. The extant genera are the snapping turtles, ''Chelydra'' and ''Macrochelys''. Both are endemic to the Western Hemisphere. The extinct genera are ''Acheronte ...

(''

Chelydridae The Chelydridae is a family of turtles that has seven extinct and two extant genera. The extant genera are the snapping turtles, ''Chelydra'' and ''Macrochelys''. Both are endemic to the Western Hemisphere. The extinct genera are ''Acherontemys' ...

'') family **

Tuatara Tuatara (''Sphenodon punctatus'') are reptiles endemic to New Zealand. Despite their close resemblance to lizards, they are part of a distinct lineage, the order Rhynchocephalia. The name ''tuatara'' is derived from the Māori language and m ...

('' Sphenodon punctatus'' and ''

Sphenodon guntheri Tuatara (''Sphenodon punctatus'') are reptiles endemic to New Zealand. Despite their close resemblance to lizards, they are part of a distinct lineage, the order Rhynchocephalia. The name ''tuatara'' is derived from the Māori language and m ...

'') **

Asian forest tortoise The Asian forest tortoise (''Manouria emys''), also known commonly as the Mountain tortoise, is a species of tortoise in the family Testudinidae. The species is endemic to Southeast Asia. It is believed to be among the most primitive of living ...

(''

Manouria emys The Asian forest tortoise (''Manouria emys''), also known commonly as the Mountain tortoise, is a species of tortoise in the family Testudinidae. The species is endemic to Southeast Asia. It is believed to be among the most primitive of living ...

'') ** Impressed tortoise (''

Manouria impressa The impressed tortoise (''Manouria impressa'') occurs in mountainous forest areas in Southeast Asia, mainly in Myanmar Burma, southern China, Thailand, Laos, Vietnam, Cambodia, Malaysia and Northeast India. The species has a golden brown shell an ...

'') ** Sunbeam snake ('' Xenopeltis hainanensis'' and '' Xenopeltis unicolor'') **

Leatherback sea turtle The leatherback sea turtle (''Dermochelys coriacea''), sometimes called the lute turtle or leathery turtle or simply the luth, is the largest of all living turtles and the heaviest non-crocodilian reptile, reaching lengths of up to and weight ...

(''Dermochelys coriacea'') * Amphibians ** Giant salamanders ('' Cryptobranchus'' and ''

Andrias ''Andrias'' is a genus of giant salamanders. It includes the largest salamanders in the world, with ''A. japonicus'' reaching a length of , and ''A. sligoi'' reaching . While extant species are only known from East Asia, several extinct specie ...

'') **

Hula painted frog The Hula painted frog (''Latonia nigriventer'') is an amphibian and the only living member of the genus '' Latonia,'' which was originally described from several fossil species from the Oligocene to Early Pleistocene of Europe. The Hula painted f ...

('' Latonia nigriventer'') ** Purple frog (''Nasikabatrachus sahyadrensis'') Nautilus profile

* Jawless fish **

Hagfish Hagfish, of the class Myxini (also known as Hyperotreti) and order Myxiniformes , are eel-shaped, slime-producing marine fish (occasionally called slime eels). They are the only known living animals that have a skull but no vertebral column, ...

(''Myxinidae'') family **

Lamprey Lampreys (sometimes inaccurately called lamprey eels) are an ancient extant lineage of jawless fish of the order Petromyzontiformes , placed in the superclass Cyclostomata. The adult lamprey may be characterized by a toothed, funnel-like s ...

(''Petromyzontiformes'') * Bony fish **

Arowana Arowanas are freshwater bony fish of the subfamily Osteoglossinae, also known as bony tongues (the latter name is now often reserved for Arapaiminae). In this family of fish, the head is bony and the elongated body is covered by large, heavy sc ...

and arapaima (''Osteoglossidae'') **

Bowfin The bowfin (''Amia calva'') is a bony fish, native to North America. Common names include mudfish, mud pike, dogfish, grindle, grinnel, swamp trout, and choupique. It is regarded as a relict, being the sole surviving species of the Halecomorp ...

(''Amia calva'') **

(the lobed-finned ''Latimeria menadoensis'' and ''Latimeria chalumnae'') ** Gar (''Lepisosteidae'') **

Queensland lungfish The Australian lungfish (''Neoceratodus forsteri''), also known as the Queensland lungfish, Burnett salmon and barramunda, is the only surviving member of the family Neoceratodontidae. It is one of only six extant lungfish species in the world. ...

(''Neoceratodus fosteri'') **

African lungfish ''Protopterus'' is the genus of four species of lungfish found in Africa. ''Protopterus'' was formerly thought to be the sole genus in the family Protopteridae, but more recent studies have classified it with ''Lepidosiren'' in the family Lepi ...

(''Protopterus sp.'') **

Sturgeons Sturgeon is the common name for the 27 species of fish belonging to the family Acipenseridae. The earliest sturgeon fossils date to the Late Cretaceous, and are descended from other, earlier acipenseriform fish, which date back to the Early ...

and

paddlefish Paddlefish (family Polyodontidae) are a family of ray-finned fish belonging to order Acipenseriformes, and one of two living groups of the order alongside sturgeons (Acipenseridae). They are distinguished from other fish by their titular elong ...

(

Acipenseriformes Acipenseriformes is an order of basal ray-finned fishes that includes living and fossil sturgeons and paddlefishes (Acipenseroidei), as well as the extinct families Chondrosteidae and Peipiaosteidae. They are the second earliest diver ...

) **

Bichir Bichirs and the reedfish comprise Polypteridae , a family of archaic ray-finned fishes and the only family in the order Polypteriformes .Helfman GS, Collette BB, Facey DE, Bowen BW. 2009. The Diversity of Fishes. West Sussex, UK: Blackwell Pu ...

(family ''Polypteridae'') ** '' Protanguilla palau'' **

Mudskipper Mudskippers are any of the 23 extant species of amphibious fish from the subfamily Oxudercinae of the goby family Oxudercidae. They are known for their unusual body shapes, preferences for semiaquatic habitats, limited terrestrial locomotion ...

(''Oxudercinae'') * Sharks ** Blind shark (''Brachaelurus waddi'') **

Bullhead shark The bullhead sharks are a small order (Heterodontiformes ) of modern sharks ( Neoselachii). The nine living species are placed in a single genus, ''Heterodontus'', in the family Heterodontidae. All are relatively small, with the largest species ...

(''Heterodontus sp.'') ** Cow shark (sixgill sharks and relatives) (''Hexanchidae'') **

Elephant shark The Australian ghostshark (''Callorhinchus milii'') is a cartilaginous fish (Chondrichthyes) belonging to the subclass Holocephali (chimaera). Sharks, rays and skates are the other members of the cartilaginous fish group and are grouped under the ...

(''Callorhinchus milii'') **

Frilled shark The frilled shark (''Chlamydoselachus anguineus'') and the southern African frilled shark (''Chlamydoselachus africana'') are the two extant species of shark in the family ''Chlamydoselachidae''. The frilled shark is considered a living fossil, ...

(''Chlamydoselachus sp.'') **

Goblin shark The goblin shark (''Mitsukurina owstoni'') is a rare species of deep-sea shark. Sometimes called a "living fossil", it is the only extant representative of the family Mitsukurinidae, a lineage some 125 million years old. This pink-skinned anim ...

(''Mitsukurina owstoni'') **

Gulper shark The gulper shark (''Centrophorus granulosus'') is a long and slender dogfish usually about three feet in length generally found in deep, murky waters all around the world. It is a light grayish brown, paler ventrally, with a long snout and lar ...

(''Centrophorus sp.'') ;Invertebrates: * Insects ** Helorid wasps (1 living genus, 11 extinct genera) ** Mantophasmatodea (gladiators; a few living species) ** Meropeidae (3 living species, 4 extinct) ** '' Micromalthus debilis'' (a

beetle Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...

) ** Mymarommatid wasps (10 living species in genus ''Palaeomymar'') ** Nevrorthidae (3 species-poor genera) ** ''

Nothomyrmecia ''Nothomyrmecia'', also known as the dinosaur ant or dawn ant, is an extremely rare genus of ants consisting of a single species, ''Nothomyrmecia macrops''. These ants live in South Australia, nesting in old-growth mallee woodland and ''Eucalyp ...

'' (known as the 'dinosaur ant') ** '' Notiothauma reedi'' (a scorpionfly relative) **

Orussidae The Orussidae or the parasitic wood wasps represent a small family of sawflies ("Symphyta"). Currently, about 93 extant and four fossil species are known. They take a key position in phylogenetic analyses of Hymenoptera, because they form the sis ...

(parasitic wood wasps; about 70 living species in 16 genera) **

Peloridiidae The Peloridiidae or moss bugs are a family of true bugs, comprising eighteen genera and thirty-four species. They are small, ranging in length from 2 to 4 mm, rarely seen, peculiarly lumpy, flattened bugs found in Patagonia (Argentina and Chi ...

(peloridiid bugs; fewer than 30 living species in 13 genera) ** Rhinorhipid beetles (1 living species, Triassic origin) ** Rotoitid wasps (2 living species, 14 extinct) ** ''

Sikhotealinia zhiltzovae ''Sikhotealinia'' is a genus of beetle containing a single species, ''Sikhotealinia zhiltzovae'', which is the only living representative of the family Jurodidae. It was discovered in the Sikhote-Alin mountains in Outer Manchuria. This "living f ...

'' (a jurodid

) ** ''

'' (Anaxyelidae cedar wood wasp) ** ''

Cyatta abscondita ''Cyatta'' is a genus of ant in the subfamily Myrmicinae containing the single species ''Cyatta abscondita''. It is considered the most recent ancestor of all fungus-farming ants and a living fossil. Etymology ''Cyatta'' is a neologism constru ...

''(most recent common relative of '' Atta'' and ''

Acromyrmex ''Acromyrmex'' is a genus of New World ants of the subfamily Myrmicinae. This genus is found in South America and parts of Central America and the Caribbean Islands, and contains 33 known species. Commonly known as "leafcutter ants" they compris ...

'' ant genera) * Crustaceans **

Glypheoidea The Glypheoidea (containing the glypheoid lobsters), is a group of lobster-like decapod crustaceans which forms an important part of fossil faunas, such as the Solnhofen limestone. These fossils included taxa such as ''Glyphea'' (from which the ...

(2 living species: ''Neoglyphea inopinata'' and ''Laurentaeglyphea neocaledonica'') ** Stomatopods (mantis shrimp) ** ''

'' (also known as tadpole shrimp; a

notostraca The order Notostraca, containing the single family Triopsidae, is a group of crustaceans known as tadpole shrimp or shield shrimp. The two genera, ''Triops'' and '' Lepidurus'', are considered living fossils, with similar forms having existed sinc ...

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapoda, decapods, ostracoda, seed shrimp, branchiopoda, branchiopods, argulidae, fish lice, krill, remipedes, isopoda, isopods, barnacles, copepods, ...

) * Molluscs ** Nautilina (e.g., ''

Nautilus pompilius The chambered nautilus (''Nautilus pompilius''), also called the pearly nautilus, is the best-known species of nautilus. The shell, when cut away, reveals a lining of lustrous nacre and displays a nearly perfect equiangular spiral, although it ...

'') ** '' Neopilina'' -

Monoplacophora Monoplacophora , meaning "bearing one plate", is a polyphyletic superclass of molluscs with a cap-like shell inhabiting deep sea environments . Extant representatives were not recognized as such until 1952; previously they were known only from ...

n ** Slit snail (e.g., ''

Entemnotrochus rumphii ''Entemnotrochus rumphii'', common name the Rumphius' slit shell, is a species of large sea snail with gills and an operculum, a marine gastropod mollusk in the family Pleurotomariidae, the slit snails.Bouchet, P. (2011). Entemnotrochus rumphii ...

'') ** ''

Vampyroteuthis infernalis The vampire squid (''Vampyroteuthis infernalis'', lit. 'vampire squid from hell') is a small cephalopod found throughout temperate and tropical oceans in extreme deep sea conditions. The vampire squid uses its bioluminescent organs and its uniqu ...

'' – the vampire squid * Other invertebrates **

Crinoid Crinoids are marine animals that make up the class Crinoidea. Crinoids that are attached to the sea bottom by a stalk in their adult form are commonly called sea lilies, while the unstalked forms are called feather stars or comatulids, which are ...

s **

Horseshoe crab Horseshoe crabs are marine and brackish water arthropods of the family Limulidae and the only living members of the order Xiphosura. Despite their name, they are not true crabs or crustaceans: they are chelicerates, most closely related to ar ...

s (only 4 living species of the class Xiphosura, family Limulidae) ** ''

Lingula anatina ''Lingula anatina'' is a brachiopod species in the genus '' Lingula''. Like others in its genus, ''L. anatina'' is a filter feeder that uses a lophophore The lophophore () is a characteristic feeding organ possessed by four major groups of a ...

'' (an inarticulate

brachiopod Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, w ...

) **

Liphistiidae The spider family Liphistiidae, recognized by Tamerlan Thorell in 1869, comprises 8 genera and about 100 species of medium-sized spiders from Southeast Asia, China, and Japan. They are among the most basal living spiders, belonging to the subord ...

(trapdoor spiders) **

Onychophora Onychophora (from grc, ονυχής, , "claws"; and , , "to carry"), commonly known as velvet worms (due to their velvety texture and somewhat wormlike appearance) or more ambiguously as peripatus (after the first described genus, '' Peripatus ...

ns (velvet worms) ** '' Rhabdopleura'' (a hemichordate) ** '' Valdiviathyris quenstedti'' (a craniforman brachiopod) ** ''

Paleodictyon nodosum ''Paleodictyon nodosum'' is a living creature thought to produce a certain form of burrow nearly identical to ''Paleodictyon'' fossils. The modern burrows were found around mid-ocean ridge systems in the Pacific and Atlantic Oceans. Although scie ...

'' (unknown)

References

External links

MyTriops introduces ''Triops'' as living fossils
{{Authority control Evolutionary biology concepts Extinction Fossils

Characteristics

Evolution and living fossils

History

Other definitions

Long-enduring

Resembles ancient species

Retains many ancient traits

Relict population

Low diversity

Operational definition

Examples

Bacteria

Protists

Plants

Fungi

Animals

See also

References

External links