Yinotheria is a proposed basal subclass clade of crown

mammals Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur o ...

uniting the

Shuotheriidae Shuotheriidae is a small family of Jurassic mammals whose remains are found in China, England and possibly Russia. They have been proposed to be close relatives of Australosphenida, the group that contains living monotremes, together forming the ...

, an extinct group of mammals from the Jurassic of Eurasia, with

Australosphenida The Australosphenida are a clade of mammals, containing mammals with tribosphenic molars, known from the Jurassic to Mid-Cretaceous of Gondwana. They are thought to have acquired their tribosphenic molars independently from those of Tribosphenid ...

, a group of mammals known from the Jurassic to Cretaceous of

Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final sta ...

, which possibly include living monotremes. Today, there are only five surviving

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...

of monotremes which live in

Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...

and

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; id, Papua, or , historically ) is the world's second-largest island with an area of . Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the wide Torres ...

, consisting of 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 four species of

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 ...

. Fossils of yinotheres have been found in

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...

Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-ei ...

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Afric ...

and

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the List of South American countries by area, second-largest ...

. Contrary to other known crown mammals, they retained postdentary bones as shown by the presence of a postdentary trough. The extant members (monotremes) developed the mammalian

middle ear The middle ear is the portion of the ear medial to the eardrum, and distal to the oval window of the cochlea (of the inner ear). The mammalian middle ear contains three ossicles, which transfer the vibrations of the eardrum into waves in the ...

independently.

Evolutionary history

According to genetic studies, Yinotheria diverged from other

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur ...

s around 220 to 210 million years ago, at some point in 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 ...

Early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-J ...

.http://timetree.org/pdf/Madsen2009Chap68.pdf The oldest-known fossils are a bit younger, dating around 168 to 163 million years in the

Middle Jurassic The Middle Jurassic is the second Epoch (geology), epoch of the Jurassic Period (geology), Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively ...

. These fossils are the genera ''

Pseudotribos ''Pseudotribos'' ("false chewing") is an extinct genus of mammal that lived in Northern China during the Middle Jurassic some , possibly more closely related to monotremes than to theria (placental and marsupial mammals), although other studies i ...

'' of China, '' Shuotherium'' of both China and England, '' Itatodon'' of

Siberia Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part ...

and '' Paritatodon'' of

Kyrgyzstan Kyrgyzstan,, pronounced or the Kyrgyz Republic, is a landlocked country in Central Asia. Kyrgyzstan is bordered by Kazakhstan to the north, Uzbekistan to the west, Tajikistan to the south, and the People's Republic of China to the ea ...

and

. These, which belong to the family

, are the only known northern hemisphere group of yinotherians. The infraclass

appeared around the same time as Shuotheriidae. The family Henosferidae, comprising the genera ''

Henosferus ''Henosferus'' is an extinct genus of australosphenidan mammal from Lower Jurassic of Argentina. The only recorded species, ''Henosferus molus'', was found in the Cañadón Asfalto Formation of the Cañadón Asfalto Basin in Chubut Province Ch ...

'', '' Ambondro'', and '' Asfaltomylos'', has been found in the southern hemisphere at locations in Argentina and Madagascar. This suggests that this family could have been more widespread and diverse in

during that time; however, due to their fragile state, some fossils might have been destroyed by geological events. The family Ausktribosphenidae and the first

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 appeared in the

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145& ...

, in the region that is now known as

Australasia Australasia is a region that comprises Australia, New Zealand and some neighbouring islands in the Pacific Ocean. The term is used in a number of different contexts, including geopolitically, physiogeographically, philologically, and ecologic ...

. Despite being found in the same region of the world and in the same time period, recent work has found that the older Henosferidae is the sister taxon to Monotremata, with Ausktribosphenidae being the next sister taxa in Australosphenida.Averianov ''et al.'', 2014 Ausktribosphenidae includes the genera ''

Bishops A bishop is an ordained clergy member who is entrusted with a position of authority and oversight in a religious institution. In Christianity, bishops are normally responsible for the governance of dioceses. The role or office of bishop is ca ...

'' and '' Ausktribosphenos''. Some 110-million-year-old monotreme fossil jaw fragments were found at Lightning Ridge,

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

. These fragments, from the species ''

Steropodon galmani ''Steropodon'' is a genus of prehistoric monotreme, or egg-laying mammal. It contains a single species, ''Steropodon galmani'', that lived about 105 to 93.3 million years ago (mya) in the Early to Late Cretaceous period. It is one of the oldest m ...

'', are the oldest known monotreme fossils. Fossils from the genera '' Kollikodon'', ''

Teinolophos ''Teinolophos'' is a prehistoric species of monotreme, or egg-laying mammal, from the Teinolophidae. It is known from four specimens, each consisting of a partial lower jawbone collected from the Wonthaggi Formation at Flat Rocks, Victoria, Aus ...

'', and ''

Obdurodon ''Obdurodon'' is a genus of extinct platypus-like Australian monotreme which lived from the Late Oligocene to the Late Miocene. Three species have been described in the genus, the type species ''Obdurodon insignis'', plus ''Obdurodon dicksoni'' a ...

'' have also been discovered. In 1991, a fossil tooth of a 61-million-year-old platypus was found in southern

(since named ''Monotrematum'', though it is now considered to be an ''Obdurodon'' species). (See fossil monotremes below.)

Molecular clock The molecular clock is a figurative term for a technique that uses the mutation rate of biomolecules to deduce the time in prehistory when two or more life forms diverged. The biomolecular data used for such calculations are usually nucleo ...

and fossil dating give a wide range of dates for the split between echidnas and platypuses, with one survey putting the split at 19 to 48 million years ago, but another putting it at 17 to 89 million years ago. All these dates are more recent than the oldest known platypus fossils, suggesting that both the short-beaked and long-beaked echidna species are derived from a platypus-like ancestor.

Systematics

History of classification

Prototheria

Originally, monotremes were classified as a subclass of mammals known as Prototheria. The names Prototheria,

Metatheria Metatheria is a mammalian clade that includes all mammals more closely related to marsupials than to placentals. First proposed by Thomas Henry Huxley in 1880, it is a more inclusive group than the marsupials; it contains all marsupials as w ...

and

Eutheria Eutheria (; from Greek , 'good, right' and , 'beast'; ) is the clade consisting of all therian mammals that are more closely related to placentals than to marsupials. Eutherians are distinguished from noneutherians by various phenotypic tra ...

(meaning "first beasts", "changed beasts", and "true beasts", respectively) refer to the three mammalian groupings that have living representatives. Each of the three may be defined as a total

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 ...

containing a living crown-group (respectively, the Monotremata,

Marsupialia Marsupials are any members of the mammalian infraclass Marsupialia. All extant marsupials are endemic to Australasia, Wallacea and the Americas. A distinctive characteristic common to most of these species is that the young are carried in a po ...

and

Placentalia Placental mammals (infraclass Placentalia ) are one of the three extant subdivisions of the class Mammalia, the other two being Monotremata and Marsupialia. Placentalia contains the vast majority of extant mammals, which are partly distinguishe ...

) plus any fossil species that are more closely related to that crown-group than to any other living animals. The threefold division of living mammals into monotremes, marsupials and placentals was already well established when

Thomas Huxley Thomas Henry Huxley (4 May 1825 – 29 June 1895) was an English biologist and anthropologist specialising in comparative anatomy. He has become known as "Darwin's Bulldog" for his advocacy of Charles Darwin's theory of evolution. The stori ...

proposed the names Metatheria and Eutheria to incorporate the two latter groups in 1880. Initially treated as subclasses, Metatheria and Eutheria are by convention now grouped as infraclasses of the subclass

Theria Theria (; Greek: , wild beast) is a subclass of mammals amongst the Theriiformes. Theria includes the eutherians (including the placental mammals) and the metatherians (including the marsupials) but excludes the egg-laying monotremes. ...

, and in more recent proposals have been demoted further (to

cohort Cohort or cohortes may refer to: * Cohort (educational group), a group of students working together through the same academic curriculum * Cohort (floating point), a set of different encodings of the same numerical value * Cohort (military unit) ...

s or even magnorders), as

cladistic Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived char ...

reappraisals of the relationships between living and fossil mammals have suggested that the Theria itself should be reduced in rank. Prototheria, on the other hand, was generally recognised as a subclass until quite recently, on the basis of a hypothesis that defined the group by two supposed

synapomorphies In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to ha ...

: (1) formation of the side wall of the braincase from a bone called the anterior lamina, contrasting with the

alisphenoid The greater wing of the sphenoid bone, or alisphenoid, is a bony process of the sphenoid bone; there is one on each side, extending from the side of the body of the sphenoid and curving upward, laterally, and backward. Structure The greater win ...

in therians; and (2) a linear alignment of molar cusps, contrasting with a triangular arrangement in therians. These characters appeared to unite monotremes with a range of

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretace ...

fossil orders (

Morganucodon ''Morganucodon'' ("Glamorgan tooth") is an early mammaliaform genus that lived from the Late Triassic to the Middle Jurassic. It first appeared about 205 million years ago. Unlike many other early mammaliaforms, ''Morganucodon'' is well represent ...

ta, Triconodonta,

Docodonta Docodonta is an order of extinct mammaliaforms that lived during the Mesozoic, from the Middle Jurassic to Early Cretaceous. They are distinguished from other early mammaliaforms by their relatively complex molar teeth, from which the order ...

and

Multituberculata Multituberculata (commonly known as multituberculates, named for the multiple tubercles of their teeth) is an extinct order of rodent-like mammals with a fossil record spanning over 130 million years. They first appeared in the Middle Jurassic, a ...

) in a broader clade for which the name Prototheria was retained, and of which monotremes were thought to be only the last surviving branch (Benton 2005: 300, 306).

Australosphenida hypothesis and Yinotheria

The evidence that was held to support Prototheria is now universally discounted. In the first place, the examination of embryos has revealed that the development of the braincase wall is essentially identical in therians and in 'prototherians': the anterior lamina simply fuses with the alisphenoid in therians, and therefore the 'prototherian' condition of the braincase wall is primitive for all mammals, while the therian condition can be derived from it. Additionally, the linear alignment of molar cusps is also primitive for all mammals. Therefore, neither of these states can supply a uniquely shared derived character that would support a 'prototherian' grouping of orders in contradistinction to Theria (Kemp 1983). In a further reappraisal, the molars of embryonic and fossil monotremes (living monotreme adults are toothless) appear to demonstrate an ancestral pattern of cusps that is similar to the triangular arrangement observed in therians. Some peculiarities of this dentition support an alternative grouping of monotremes with certain recently discovered fossil forms into a proposed new clade known as the

, and also suggest that the triangular array of cusps may have evolved independently in australosphenidans and therians (Luo ''et al.'' 2001, 2002). Australosphenida is characterized by the shared presence of a cingulum on the outer front corner of the lower molars, a short and broad talonid, a relatively low trigonid, and a triangulated last lower premolar. The Australosphenida hypothesis remains controversial; for example, lingual cingula seem to be a presence in various non-australosphenidan mammalsSigogneau-Russell et al., 2001, p. 146 and some work has shown the possibility of Eutheria being the sister group to Australosphenida, without monotremes. As a result, some taxonomists (e.g. McKenna & Bell 1997) prefer to maintain the name Prototheria as a fitting contrast to the other group of living mammals, the Theria. In theory, the Prototheria is taxonomically redundant, since Monotremata is currently the only order that can still be confidently included, but its retention might be justified if new fossil evidence, or a re-examination of known fossils, enables extinct relatives of the monotremes to be identified and placed within a wider grouping. When systematic work was performed, it was also found that Australosphenida is the sister taxon to

, an obscure group of Mesozoic mammals that were found in what is now

. had this to say regarding the Shuotheriidae, particularly ''Shuotherium'': Yinotheria is named for this grouping.

Taxonomy

In comparison to

and

, where there seems to be a better understanding on the relationships among taxa with substantial fossil evidence, Yinotheria has few fossils; mostly consisting of (with few exceptions) the jawbones and teeth. In addition, the group seems not to have been as diverse in their evolutionary history, in comparison to members of both Metatheria and Eutheria. Future analysis and better fossil remains could affect the membership of Yinotheria as well as rearranging and revising the relationships of stem-monotremes and crowned monotremes. * Subclass Yinotheria Chow & Rich 1982 sensu Kielan-Jaworowska, Cifelli & Luo 2004 rototheria Gill 1872** Order Shuotherida Chow & Rich 1982 huotheridia; Shuotheria*** Family

Chow & Rich 1982 **** Genus ''

'' Luo, Ji & Yuan 2007 ***** '' Pseudotribos robustus'' Luo, Ji & Yuan 2007 **** Genus '' Shuotherium'' Chow & Rich 1982 ***** '' Shuotherium dongi'' Chow & Rich 1982 ***** '' Shuotherium shilongi'' Wang et al. 1998 ** Infraclass

Luo, Cifelli & Kielan-Jaworowska 2001 sensu Kielan-Jaworowska, Cifelli & Luo 2004 *** Order

Ausktribosphenida Ausktribosphenidae is an extinct family of australosphenidan mammals from the Early Cretaceous of Australia and mid Cretaceous of South America. Classification and taxonomy Ausktribosphenidae is closely related to monotremes and hence the two f ...

Luo, Cifelli & Kielan-Jaworowska 2001 **** Family Ausktribosphenidae Rich et al. 1997 ***** Genus ''

'' Rich et al. 2001 ****** '' Bishops whitmorei'' Rich et al. 2001 ***** Genus '' Ausktribosphenos'' Rich et al. 1997 ****** ''

Ausktribosphenos nyktos ''Ausktribosphenos'' is an extinct genus of mammals from Early Cretaceous of Australia. The only recorded species, ''Ausktribosphenos nyktos'', was found on Flat Rocks, Victoria Victoria most commonly refers to: * Victoria (Australia), a s ...

'' Rich et al. 1997 *** Order Henosferida Averianov & Lopatin 2011 **** Family Henosferidae Rougier et al. 2007 ***** Genus '' Ambondro''Woodburne, 2003 ****** ''

Ambondro mahabo ''Ambondro mahabo'' is a mammal from the Middle Jurassic (Bathonian) Isalo III Formation (about 167 million years ago) of Madagascar. The only described species of the genus ''Ambondro'', it is known from a fragmentary lower jaw with three teeth ...

'' Flynn et al. 1999 ***** Genus '' Asfaltomylos'' Rauhut et al. 2002 ****** '' Asfaltomylos patagonicus'' Rauhut et al. 2002 ***** Genus ''

'' Rougier et al. 2007 ****** '' Henosferus molus'' Rougier et al. 2007 *** Order Monotremata Bonaparte 1837 sensu Luo, Cifelli & Kielan-Jaworowska 2001 **** Family

Incertae sedis ' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertain ...

***** Genus '' Kryoryctes'' Pridmore et al. 2005 (either a stem-monotreme or junior synonym of ''

Steropodon ''Steropodon'' is a genus of prehistoric monotreme, or egg-laying mammal. It contains a single species, ''Steropodon galmani'', that lived about 105 to 93.3 million years ago (mya) in the Early to Late Cretaceous period. It is one of the oldest m ...

'') ****** '' Kryoryctes cadburyi'' Pridmore et al. 2005 **** Family Tachyglossidae Gill 1872 Echidnidae_Burnett_1830.html" ;"title="Echidnidae.html" ;"title="Echidnidae">Echidnidae Burnett 1830">Echidnidae.html" ;"title="Echidnidae">Echidnidae Burnett 1830(echidnas, spiny anteaters) ***** Genus ''Megalibgwilia'' Griffiths, Wells & Barrie 1991 (subjective synonym or subgenus of ''Zaglossus'') ****** ''Megalibgwilia robusta'' (Dun 1895) (subjective synonym of ''Zaglossus robustus'') ****** '' Megalibgwilia ramsayi'' (Owen 1884) (senior synonym of '' Megalibgwilia owenii''Ashwell, 2013) ***** Genus '' Zaglossus'' Gill 1877 'Proechidna''_Gervais_1877;_''Acanthoglossus.html" ;"title="Proechidna.html" ;"title="'Proechidna">'Proechidna'' Gervais 1877; ''Acanthoglossus">Proechidna.html" ;"title="'Proechidna">'Proechidna'' Gervais 1877; ''Acanthoglossus'' Gervais 1877; ''Bruynia'' Dubois 1882; ''Bruijia'' Thomas 1883; ''Prozaglossus'' Kerbert 1913] (Long-beaked Echidnas) ****** ''Murrayglossus'' Glauert 1914 (Hackett's Giant Echidna) (might belong to a new genus) ****** ''

Zaglossus bruijni The western long-beaked echidna (''Zaglossus bruijnii'') is one of the four extant echidnas and one of three species of ''Zaglossus'' that occurs in New Guinea. Originally described as ''Tachyglossus bruijnii'', this is the type species of ''Zagl ...

'' (Peters & Doria 1876) (Western Long-beaked/Bruinj's/Brown False Echidna) ****** '' Zaglossus attenboroughii'' Flannery & Groves 1998 (Attenborough's/Sir David's/Cyclops Long-beaked Echidna) ****** '' Zaglossus bartoni'' Thomas 1907 (Eastern/Barton's Long-beaked/Grey False Echidna) ***** Genus '' Tachyglossus'' Illiger 1811 'Acanthonotus''_Goldfuss_1809;_''Echidna.html" ;"title="Acanthonotus.html" ;"title="'Acanthonotus">'Acanthonotus'' Goldfuss 1809; ''Echidna">Acanthonotus.html" ;"title="'Acanthonotus">'Acanthonotus'' Goldfuss 1809; ''Echidna'' Cuvier 1798; ''Echinopus'' Fischer de Waldheim 1814; ''Syphomia'' Rafinesque 1815] ****** ''Tachyglossus aculeatus'' (Shaw 1792) Illiger 1811 (short-beaked Echidna) **** Family Kollikodontidae Flannery et al. 1995 ***** Genus '' Kollikodon'' Flannery et al. 1995 (might be a mammaliform of uncertain placement) ****** '' Kollikodon ritchiei'' Flannery et al. 1995 **** Family Steropodontidae Archer et al. 1985 ***** Genus ''

'' Rich et al. 1999 (might be a basal monotreme or a stem-monotreme) ****** '' Teinolophos trusleri'' Rich et al. 1999 ***** Genus ''

'' Archer et al. 1985 ****** ''

'' Archer et al. 1985 **** Family

Ornithorhynchidae The Ornithorhynchidae are one of the two extant families in the order Monotremata, and contain the platypus and its extinct relatives. The other family is the Tachyglossidae, or echidnas. Within the Ornithorhynchidae are the genera '' Monotrem ...

Gray 1825 ***** Genus '' Monotrematum'' Pascual et al. 1992 (here considered to be a basal ornithorhynchid; others subjective synonym of ''Obdurodon'') ****** ''

Monotrematum sudamericanum ''Monotrematum sudamericanum'' is an extinct monotreme species from the Paleocene (Peligran) Salamanca Formation in Patagonia, Argentina. It is the only monotreme found outside Oceania. Taxonomy A species described in 1992 and assigned to a n ...

'' Pascual et al. 1992 ***** Genus ''

'' Woodburne & Tedford 1975 ****** ''

Obdurodon insignis ''Obdurodon'' is a genus of extinct platypus-like Australian monotreme which lived from the Late Oligocene to the Late Miocene. Three species have been described in the genus, the type species ''Obdurodon insignis'', plus ''Obdurodon dicksoni' ...

'' Woodburne & Tedford 1975 ****** ''

Obdurodon tharalkooschild ''Obdurodon'' is a genus of extinct platypus-like Australian monotreme which lived from the Late Oligocene to the Late Miocene. Three species have been described in the genus, the type species ''Obdurodon insignis'', plus ''Obdurodon dicksoni'' a ...

'' Pian, Archer & Hand 2013 ****** ''

Obdurodon dicksoni ''Obdurodon'' is a genus of extinct platypus-like Australian monotreme which lived from the Late Oligocene to the Late Miocene. Three species have been described in the genus, the type species ''Obdurodon insignis'', plus ''Obdurodon dicksoni'' ...

'' Archer et al. 1992 (Riversleigh platypus) ***** Genus ''

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 ...

'' Blumenbach 1800 'Dermipus''_Wiedermann_1800;_''Platypus.html" ;"title="Dermipus.html" ;"title="'Dermipus">'Dermipus'' Wiedermann 1800; ''Platypus">Dermipus.html" ;"title="'Dermipus">'Dermipus'' Wiedermann 1800; ''Platypus'' Shaw 1799 non Herbst 1793] ****** ''Ornithorhynchus anatinus'' (Shaw 1799) Blumenbach 1800 (platypus)

Phylogeny

Below is a simplified tree on Averianov ''et al.'', 2014 after Woodburn, 2003 and Ashwell, 2013

References

Bibliography

* * * * * * * McKenna, Malcolm C., and Susan K. Bell. 1997. ''Classification of Mammals Above the Species Level''. New York: Columbia University Press. *

External links

* * {{Taxonbar, from=Q21448022 Mammal taxonomy Vertebrate subclasses Extant Late Triassic first appearances Taxa named by Zhou Mingzhen Taxa named by Tom Rich