Monotremes[1] Fossil range: Early Cretaceous - Recent
Short-beaked Echidna
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia (unranked) Australosphenida Order: Monotremata C.L. Bonaparte, 1837
Families
†Kollikodontidae Ornithorhynchidae Tachyglossidae †Steropodontidae // The Cretaceous Period is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic Period (i. ... Image File history File links Size of this preview: 800 × 534 pixelsFull resolution (1600 × 1067 pixel, file size: 616 KB, MIME type: image/jpeg) Echidna, Melbourne Zoo If you are a (commercial) publisher and you want me to write you an email or paper mail giving you an authorization to... Binomial name Tachyglossus aculeatus (Shaw, 1792) The Short-beaked Echidna (Tachyglossus aculeatus), also known as the Spiny Anteater because of its diet of ants and termites, is one of four living species of echidna and the only member of the genus Tachyglossus. ... For other uses, see Scientific classification (disambiguation). ... For other uses, see Animal (disambiguation). ... Typical Classes See below Chordates (phylum Chordata) are a group of animals that includes the vertebrates, together with several closely related invertebrates. ... Subclasses & Infraclasses Subclass †Allotheria* Subclass Prototheria Subclass Theria Infraclass †Trituberculata Infraclass Metatheria Infraclass Eutheria Mammals (class Mammalia) are warm-blooded, vertebrate animals characterized by the presence of sweat glands, including milk producing sweat glands, and by the presence of: hair, three middle ear bones used in hearing, and a neocortex... The Australosphenida are a sub-class of mammals which has nearly entirely died out. ... Charles Lucien Jules Laurent Bonaparte (May 24, 1803 – July 29, 1857) was a French naturalist and ornithologist. ... Binomial name Kollikodon ritchiei Flannery, Archer, Rich & Jones, 1995 Kollikodon ritchiei is an extinct monotreme species. ... Genera Obdurodon (extinct) Ornithorhynchus Ornithorhyncidae is one of two families in the order Monotremata, and contains all species of platypus. ... For other senses of this word, see echidna (disambiguation). ... Binomial name Steropodon galmani Archer, Flannery, Ritchie, & Molnar, 1985 Steropodon galmani was a prehistoric monotreme, or egg-laying mammal species that lived during the middle Albian stage, in the Lower Cretaceous period. ...

Monotremes (from the Greek monos 'single' + trema 'hole', referring to the cloaca) are mammals that lay eggs (Prototheria) instead of giving birth to live young like marsupials (Metatheria) and placental mammals (Eutheria). In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, urinary, and genital tracts of certain animal species. ... Subclasses & Infraclasses Subclass †Allotheria* Subclass Prototheria Subclass Theria Infraclass †Trituberculata Infraclass Metatheria Infraclass Eutheria Mammals (class Mammalia) are warm-blooded, vertebrate animals characterized by the presence of sweat glands, including milk producing sweat glands, and by the presence of: hair, three middle ear bones used in hearing, and a neocortex... Prototheria (próto-thiŕ ee-a) (Gr. ... Orders Superorder Ameridelphia Didelphimorphia Paucituberculata Superorder Australidelphia Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Marsupials are mammals in which the female typically has a pouch (called the marsupium, from which the name Marsupial derives) in which it rears its young through early infancy. ... Metatheria is a grouping within the animal class Mammalia. ... Orders Superorder Xenarthra: Pilosa Cingulata Infraclass Epitheria: Superorder Afrotheria: Afrosoricida (Golden mole and tenrec) Macroscelidea (Elephant shrew) Tubulidentata (Aardvark) Hyracoidea (Hyrax) Proboscidea (Elephant) Sirenia (Manatee, Dugong) Superorder Laurasiatheria: Chiroptera (Bats) Insectivora (Shrews, Moles) Cetacea (Whale, dolphin) Artiodactyla (Ruminants et al) Perissodactyla(Horse et al. ... Orders[1] Bobolestes Eomaia Maelestes Montanalestes Murtoilestes Prokennalestes Placentalia Superorder Xenarthra: Cingulata (Armadillos) Pilosa (Sloths, True Anteaters) Superorder Afrotheria: Afrosoricida (Tenrecs, etc. ...

They are conventionally treated as comprising a single order Monotremata, though a recent classification proposes to divide them into the orders Platypoda (the Platypus along with its fossil relatives) and Tachyglossa (the echidnas). The entire grouping is also traditionally placed into a subclass Prototheria, which was extended to include several fossil orders but these are no longer seen as constituting a natural group allied to monotreme ancestry. A controversial hypothesis now relates the monotremes to a different assemblage of fossil mammals in a clade termed Australosphenida. Binomial name Ornithorhynchus anatinus (Shaw, 1799) The platypus (Ornithorhynchus anatinus) is a small, half-aquatic mammal endemic to the eastern part of Australia, and one of the five extant species of monotremes, the only mammals that lay eggs instead of giving birth to live young (the other four are echidnas). ... For other uses, see Platypus (disambiguation). ... Species Genus Tachyglossus    T. aculeatus Genus Zaglossus    Z. attenboroughi    Z. bruijnii    Z. bartoni    Z. hacketti(extinct)    Z. robustus(extinct) Echidnas, also decreasingly referred to by the name spiny anteaters, are the only surviving monotremes apart from the Platypus. ... For other senses of this word, see echidna (disambiguation). ... A clade is a term belonging to the discipline of cladistics. ... The Australosphenida are a sub-class of mammals which has nearly entirely died out. ...

Monotremes are among the small number of mammalian species known to be capable of electroreception. Electroreception, sometimes written as electroception, is the biological ability to receive and make use of electrical impulses. ...

General characteristics

Like other mammals, monotremes are warm-blooded with a high metabolic rate (though not as high as other mammals, see below); have hair on their bodies; produce milk, through mammary glands, to feed their young; have a single bone in their lower jaw; and have three middle ear bones. A warm-blooded (homeothermic) animal is one that can keep its core body temperature at a nearly constant level regardless of the temperature of the surrounding environment (that is, to maintain thermal homeostasis) . This can involve not only the ability to generate heat, but also the ability to cool down... For the 1968 stage production, see Hair (musical), for the 1979 film, see Hair (film). ... A glass of cows milk. ... The middle ear is the portion of the ear internal to the eardrum, and external to the oval window of the cochlea. ...

Monotremes were very poorly understood for many years, and to this day some of the 19th century myths that grew up around them endure. It is still sometimes thought, for example, that the monotremes are "inferior" or quasi-reptilian, and that they are a distant ancestor of the "superior" placental mammals. It now seems plain that modern monotremes are the survivors of an early branching of the mammal tree; a later branching is thought to have led to the marsupial and placental groups. Alternative meaning: Nineteenth Century (periodical) (18th century — 19th century — 20th century — more centuries) As a means of recording the passage of time, the 19th century was that century which lasted from 1801-1900 in the sense of the Gregorian calendar. ... This article is about mammals. ... Orders Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia Xenarthra Dermoptera: Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Placentalia and Eutheria are terms used to describe major groupings within the animal class of Mammalia. ...

Similarly, it is still sometimes said that monotremes have less developed internal temperature control mechanisms than other mammals, but more recent research shows that monotremes maintain a constant body temperature in a wide variety of circumstances without difficulty (for example, the Platypus while living in an icy mountain stream). Early researchers were misled by two factors: monotremes maintain a lower average temperature than most mammals (around 32°C [90°F], compared to about 35°C [95°F] for marsupials, and 38°C [100°F] for most placentals); secondly, the Short-beaked Echidna (which is much easier to study than the reclusive Platypus) only maintains normal temperature when it is active: during cold weather, it conserves energy by "switching off" its temperature regulation. Finally, poor thermal regulation has also been observed in the hyraxes, which are placental mammals. Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when temperature surrounding is very different. ... Binomial name Tachyglossus aculeatus (Shaw, 1792) The Short-beaked Echidna (Tachyglossus aculeatus), also known as the Spiny Anteater because of its diet of ants and termites, is one of four living species of echidna and the only member of the genus Tachyglossus. ... Genera Procavia Heterohyrax Dendrohyrax A hyrax (from Greek shrewmouse; Afrikaans: klipdassie) is any of four species of fairly small, thickset, herbivorous mammals in the order Hyracoidea. ...

Physiology

A Platypus

A Long-beaked Echidna

The key physiological difference between monotremes and other mammals is the one that gave them their name; Monotreme means 'single opening' in Greek, and comes from the fact that their urinary, defecatory, and reproductive systems all open into a single duct, the cloaca. This structure is very similar to the one found in reptiles. Monotremes and marsupials have a single cloaca while placental mammal females have separate openings for reproduction, urination and defecation: the vagina, the urethra, and the anus. This file was found by the Pics4Learning Search Engine, which guarantees copyright-free images. ... This file was found by the Pics4Learning Search Engine, which guarantees copyright-free images. ... For other uses, see Platypus (disambiguation). ... Image File history File links Long-beakedEchidna. ... Image File history File links Long-beakedEchidna. ... Binomial name Zaglossus bruijnii (Peters and Doria, 1876) The Long-beaked Echidna is one of the four extant echidnas and one of three species of Zaglossus that occur in New Guinea. ... In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, urinary, and genital tracts of certain animal species. ... The vagina, (from Latin, literally sheath or scabbard ) is the tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. ... In anatomy, the urethra is a tube which connects the urinary bladder to the outside of the body. ... This article is about the bodily orifice. ...

Monotremes lay eggs. However, the egg is retained for some time within the mother, who actively provides the egg with nutrients. Monotremes also lactate, but have no defined nipples, excreting the milk from their mammary glands via openings in their skin. All species are long-lived, with low rates of reproduction and relatively prolonged parental care of infants. Infant echidnas are commonly known as puggles; the same term, though not generally accepted, is popularly applied to young platypus as well.^[2][3] In most birds and reptiles, an egg (Latin ovum) is the zygote, resulting from fertilization of the ovum. ... This article is about the anatomical structure. ... Mammary glands are the organs that, in the female mammal, produce milk for the sustenance of the young. ...

Living monotremes lack teeth as adults. Fossil forms and modern platypus young have the "tribosphenic" molars (with the occlusal surface formed by three cusps arranged in a triangle), which are one of the hallmarks of extant mammals. However, recent work suggests that monotremes acquired this form of molar independently of placental mammals and marsupials,^[4] although this is not well established.^[5] The jaw of monotremes is constructed somewhat differently from those of other mammals, and the jaw opening muscle is different. As in all true mammals, the tiny bones that conduct sound to the inner ear are fully incorporated into the skull, rather than lying in the jaw as in cynodonts and other pre-mammalian synapsids; however, this feature, too, is now claimed to have evolved independently in monotremes and therians,^[6] although, like the analogous evolution of the tribosphenic molar, this is disputed.^[7][8] The imminent sequencing of the platypus genome should shed light on this and many other questions regarding the evolutionary history of the monotremes.^[9] Molars are the rearmost and most complicated kind of tooth in most mammals. ... There are numerous commonly used terms of relationship and comparison that refer to different aspects of teeth and are frequently utilized in articles about dentistry. ... A cusp is an occlusal or incisal eminance on a tooth. ... Clades Procynosuchidae Epicynodontia Galesauridae Eucynodontia Cynognathia Cynognathidae Tritylodontidae Probainognathia Trithelodontidae Mammaliformes Cynodonta, or dog teeth, were one of the most diverse groups of therapsids. ... Groups Caseasauria Eupelycosauria    Sphenacodontia       Therapsida          (...mammals) Synapsids (fused arch), formerly known as mammal-like reptiles, are a group of amniotes (reptiles and all their ancestors) that developed one hole in their skull (temporal fenestra) behind each eye, about 320 million years ago (Ma) during the late Carboniferous. ... Infraclasses Metatheria Eutheria This article is about the subclass of mammals. ...

However, the external opening of the ear still lies at the base of the jaw. The monotremes also have extra bones in the shoulder girdle, including an interclavicle, which are not found in other mammals. Monotremes retain a reptile-like gait, with legs that are on the sides of rather than underneath the body. The monotreme leg bears a spur in the ankle region; the spur is non-functional in echidnas, but contains a powerful venom in the male platypus. The poison-delivering spur is found only on the males hind limbs. ...

Their metabolic rate is remarkably low by mammalian standards, although the extent to which this is a characteristic of monotremes, as opposed to an adaptation on the part of the small number of surviving species to harsh environmental conditions, is uncertain.

Taxonomy

The only surviving examples of monotremes are all indigenous to Australia and New Guinea, although there is evidence that they were once more widespread. Fossil and genetic evidence shows that the monotreme line diverged from other mammalian lines about 150 million years ago and that both the short-beaked and long-beaked echidna species are derived from a platypus-like ancestor. Fossils of a jaw fragment 110 million years old were found at Lightning Ridge, New South Wales. These fragments, from species Steropodon galmani, are the oldest known fossils of monotremes. Fossils from the genera Kollikodon, Teinolophos, and Obdurodon have also been discovered. In 1991, a fossil tooth of a 61-million-year-old platypus was found in southern Argentina (since named Monotrematum, though it is now considered to be an Obdurodon species). (See fossil monotremes below.) For other uses, see Platypus (disambiguation). ... Lightning Ridge is a town of approximately 2000 persons in north-western New South Wales, Australia. ... NSW redirects here. ... Binomial name Steropodon galmani Archer, Flannery, Ritchie, & Molnar, 1985 Steropodon galmani was a prehistoric monotreme, or egg-laying mammal species that lived during the middle Albian stage, in the Lower Cretaceous period. ... Kollikodon is an extinct species of Monotreme. ... Binomial name Rich et al. ... Species Obdurodon dicksoni Obdurodon insignis Monotrematum sudamericanum Obdurodon is an extinct genus of platypus containing three species. ... Year 1991 (MCMXCI) was a common year starting on Tuesday (link will display the 1991 Gregorian calendar). ...

• ORDER MONOTREMATA
  • Family Ornithorhynchidae: platypus
    • Genus Ornithorhynchus
      • Platypus, Ornithorhynchus anatinus
  • Family Tachyglossidae: echidnas
    • Genus Tachyglossus
      • Short-beaked Echidna, Tachyglossus aculeatus
    • Genus Zaglossus
      • Western Long-beaked Echidna, Zaglossus brujinii
      • Sir David's Long-beaked Echidna, Zaglossus attenboroughi
      • Eastern Long-beaked Echidna, Zaglossus bartoni

Genera Obdurodon (extinct) Ornithorhynchus Ornithorhyncidae is one of two families in the order Monotremata, and contains all species of platypus. ... This article is about the monotreme mammal. ... For other uses, see Platypus (disambiguation). ... For other uses, see Echidna (disambiguation). ... This page is a candidate for speedy deletion, because: it is patent nonsense. ... Binomial name Tachyglossus aculeatus (Shaw, 1792) The Short-beaked Echidna (Tachyglossus aculeatus), also known as the Spiny Anteater because of its diet of ants and termites, is one of four living species of echidna and the only member of the genus Tachyglossus. ... Species Zaglossus attenboroughi Zaglossus bartoni Zaglossus bruijnii Zaglossus hacketti (extinct) Zaglossus robustus (extinct) Zaglossus is the genus of the echidna, a spiny monotreme that lives in New Guinea. ... Binomial name Zaglossus bruijnii (Peters and Doria, 1876) The Western Long-beaked Echidna is one of the four extant echidnas and one of three species of Zaglossus that occur in New Guinea. ... Binomial name Flannery & Groves, 1998 Sir Davids Long-beaked Echidna (Zaglossus attenboroughi), also known as the Attenboroughs Long-beaked Echidna or Cyclops Long-beaked Echidna, is one of three species from the genus Zaglossus to occur in New Guinea. ... Binomial name Zaglossus bartoni (Thomas, 1907) The Eastern Long-beaked Echidna (Zaglossus bartoni), also known as Bartons Long-beaked Echidna, is one of three species from the genus Zaglossus to occur in New Guinea. ...

Fossil monotremes

Excepting Ornithorhynchus anatinus, all the animals listed in this section are only known from fossils.

• Family Kollikodontidae
  • Genus Kollikodon
    • Species Kollikodon ritchiei. Ancient monotreme, 100-105 million years old.
• Family Ornithorhynchidae
  • Genus Ornithorhynchus. Oldest Ornithorhynchus specimen 9 million years old.
    • Species Ornithorhynchus anatinus (Platypus). Oldest specimen 10,000 years old.
  • Genus Obdurodon. Includes a number of Miocene (5-24 million years ago) Platypuses.
    • Species Obdurodon dicksoni
    • Species Obdurodon insignis
    • Species Monotrematum sudamericanum. 61 million years old. (Originally placed in separate genus, now thought an Obdurodon)
• Family Tachyglossidae
  • Genus Zaglossus. Upper Pleistocene (.1-1.8 million years ago).
    • Species Zaglossus hacketti
    • Species Zaglossus robustus
  • Genus Megalibgwilia
    • Megalibgwiilia ramsayi Late Pleistocene
    • Megalibgwiilia robusta Miocene
• Family Steropodontidae. May be part of Ornithorhynchidae; closely related to modern platypus.
  • Genus Steropodon
    • Species Steropodon galmani.
  • Genus Teinolophos
    • Species Teinolophos trusleri. 123 million years old — oldest monotreme specimen.

Binomial name Kollikodon ritchiei Flannery, Archer, Rich & Jones, 1995 Kollikodon ritchiei is an extinct monotreme species. ... Kollikodon is an extinct species of Monotreme. ... Binomial name Kollikodon ritchiei Flannery, Archer, Rich & Jones, 1995 Kollikodon ritchiei is an extinct monotreme species. ... Genera Obdurodon (extinct) Ornithorhynchus Ornithorhyncidae is one of two families in the order Monotremata, and contains all species of platypus. ... This article is about the monotreme mammal. ... This article is about the monotreme mammal. ... For other uses, see Platypus (disambiguation). ... Species Obdurodon dicksoni Obdurodon insignis Monotrematum sudamericanum Obdurodon is an extinct genus of platypus containing three species. ... The Miocene Epoch is a period of time that extends from about 23. ... Species Obdurodon dicksoni Obdurodon insignis Monotrematum sudamericanum Obdurodon is an extinct genus of platypus containing three species. ... Species Obdurodon dicksoni Obdurodon insignis Monotrematum sudamericanum Obdurodon is an extinct genus of platypus containing three species. ... Species Obdurodon dicksoni Obdurodon insignis Monotrematum sudamericanum Obdurodon is an extinct genus of platypus containing three species. ... For other uses, see Echidna (disambiguation). ... Species Zaglossus attenboroughi Zaglossus bartoni Zaglossus bruijnii Zaglossus hacketti (extinct) Zaglossus robustus (extinct) Zaglossus is the genus of the echidna, a spiny monotreme that lives in New Guinea. ... The Pleistocene epoch (IPA: ) on the geologic timescale is the period from 1,808,000 to 11,550 years BP. The Pleistocene epoch had been intended to cover the worlds recent period of repeated glaciations. ... Species Zaglossus attenboroughi Zaglossus brujinii Zaglossus hacketti (extinct) Zaglossus robustus (extinct) Zaglossus is the genus of the echidna, a spiny monotreme that lives in Australia. ... Species Zaglossus attenboroughi Zaglossus brujinii Zaglossus hacketti (extinct) Zaglossus robustus (extinct) Zaglossus is the genus of the echidna, a spiny monotreme that lives in Australia. ... Species † (Owen, 1884) † (Dun, 1896) Megalibgwilia is a genus of echidna only known from fossils from Australia, it incorporates the oldest known echidna species. ... Late Pleistocene (also known as Upper Pleistocene or the Tarantian) is a stage of the Pleistocene Epoch. ... The Miocene Epoch is a period of time that extends from about 23. ... Binomial name Steropodon galmani Archer, Flannery, Ritchie, & Molnar, 1985 Steropodon galmani was a prehistoric monotreme, or egg-laying mammal species that lived during the middle Albian stage, in the Lower Cretaceous period. ... Binomial name Archer, Flannery, Ritchie, & Molnar, 1985 Steropodon galmani was a prehistoric species of monotreme, or egg-laying mammal, that lived during the middle Albian stage, in the Lower Cretaceous period. ... Binomial name Steropodon galmani Archer, Flannery, Ritchie, & Molnar, 1985 Steropodon galmani was a prehistoric monotreme, or egg-laying mammal species that lived during the middle Albian stage, in the Lower Cretaceous period. ... Binomial name Rich et al. ... Binomial name Teinolophos trusleri Teinolophos trusleri was a prehistoric monotreme, or egg-laying mammal. ...

Media

An echidna building a defensive burrow on French Island

French Island National Park is located on French Island on Western Port, Victoria, (Australia), 61 km southeast of Melbourne. ...

References

General references

Dr Colin Groves is a Professor of Biological Anthropology at the Australian National University in Canberra, Australia. ... is the 320th day of the year (321st in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 294th day of the year (295th in leap years) in the Gregorian calendar. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance to the Gregorian calendar. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 294th day of the year (295th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 294th day of the year (295th in leap years) in the Gregorian calendar. ... Ensembl is a bioinformatics research project aiming to develop a software system which produces and maintains automatic annotation on selected eukaryotic genomes. It is run in a collaboration between the Wellcome Trust Sanger Institute and the European Bioinformatics Institute, an outstation of the European Molecular Biology Laboratory. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 294th day of the year (295th in leap years) in the Gregorian calendar. ...

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• Monotreme Reproductive Biology and Behavior