Temporal range: Early Cretaceous (Barremian) – Present
PreꞒ
Ꞓ
O
S
D
C
P
T
J
K
Pg
N
Four of the five extant monotreme species: platypus (top-left), short-beaked echidna (top-right), western long-beaked echidna (bottom-left), and replica eastern long-beaked echidna (bottom-right)
Scientific classification
Domain:
Eukaryota
Kingdom:
Animalia
Phylum:
Chordata
Class:
Mammalia
Order:
Monotremata C.L. Bonaparte, 1837[2]
Subgroups
†Kryoryctes?
†Patagorhynchus
†Sundrius?
†Steropodontidae
†Teinolophidae
†Kollikodontidae
Ornithorhynchidae
Tachyglossidae
Monotremes (/ˈmɒnətriːmz/) are mammals of the order Monotremata. They are the only known group of living mammals that lay eggs, rather than bearing live young. The extant monotreme species are the platypus and the four species of echidnas. Monotremes are typified by structural differences in their brains, jaws, digestive tract, reproductive tract, and other body parts, compared to the more common mammalian types. Although they are different from almost all mammals in that they lay eggs, like all mammals, the female monotremes nurse their young with milk.
Monotremes have been considered by some authors to be members of Australosphenida, a clade that contains extinct mammals from the Jurassic and Cretaceous of Madagascar, South America, and Australia, but this categorization is disputed and their taxonomy is under debate.
All extant species of monotremes are indigenous to Australia and New Guinea, although they were also present in the Late Cretaceous and Paleocene of southern South America, implying that they were also present in Antarctica, though remains have not been found there.
The name monotreme derives from the Greek words μονός (monós 'single') and τρῆμα (trêma 'hole'), referring to the cloaca.
^Groves, C. P. (2005). Wilson, D. E.; Reeder, D. M. (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Baltimore: Johns Hopkins University Press. pp. 1–2. ISBN 0-801-88221-4. OCLC 62265494.
^Bonaparte, C.L. (1837). "A New Systematic Arrangement of Vertebrated Animals". Transactions of the Linnean Society of London. 18 (3): 258. doi:10.1111/j.1095-8339.1838.tb00177.x.
Monotremes (/ˈmɒnətriːmz/) are mammals of the order Monotremata. They are the only known group of living mammals that lay eggs, rather than bearing live...
the five extant species of monotremes, mammals that lay eggs instead of giving birth to live young. Like other monotremes, the platypus senses prey in...
Echidnas (/ɪˈkɪdnəz/), sometimes known as spiny anteaters, are quill-covered monotremes (egg-laying mammals) belonging to the family Tachyglossidae /tækiˈɡlɒsɪdiː/...
Steropodon is a genus of prehistoric platypus-like monotreme, or egg-laying mammal. It contains a single species, Steropodon galmani, that lived about...
based on reproductive techniques: egg-laying mammals (yinotherians or monotremes - see also Australosphenida), and mammals which give live birth (therians)...
All modern mammals give birth to live young, except the five species of monotremes, which are egg-laying mammals. The most species-rich group of mammals...
exceptions are reported) and epipubic bones are present. Marsupials (and monotremes) also lack a gross communication (corpus callosum) between the right and...
cynodonts. Most of the animals in this group are extinct. The egg-laying monotremes are known from fossils of the Cretaceous and Cenozoic periods; they are...
subclasses based on reproductive techniques: egg laying mammals (the monotremes), and live birth mammals. The second subclass is divided into two infraclasses:...
Michael; Rich, Thomas H.; Jones, Robert (5 October 1995). "A new family of monotremes from the Creataceous of Australia". Nature. 377 (6548): 418–420. Bibcode:1995Natur...
vertebrate animals. All amphibians, reptiles, birds, and a few mammals (monotremes, tenrecs, golden moles, and marsupial moles), have this orifice, from...
although some, such as scorpions, do not. Reptile eggs, bird eggs, and monotreme eggs are laid out of water and are surrounded by a protective shell, either...
extant mammalian species, dominated by the marsupials, but also including monotremes and placentals. The marsupials evolved to fill specific ecological niches...
of the only distantly related erinaceomorph hedgehogs and Australian monotreme echidnas as well as tenrecid tenrecs. The word "porcupine" comes from...
Purpose-inator", and Agent P must defeat him before he find it. 121 9 "Misperceived Monotreme" Jay Lender Kaz & Tom Minton Martin Olson May 13, 2011 (2011-05-13) 305b...
Patagorhynchus is a genus of prehistoric monotreme mammal from the Late Cretaceous (early Maastrichtian) Chorrillo Formation of Santa Cruz Province, Argentina...
an extinct monotreme species from the Paleocene (Peligran) Salamanca Formation in Patagonia, Argentina. It is one of only two monotremes found outside...
very close analogue to eutherian mammalian placental development. In monotremes, mammals which lay eggs, namely the platypus and the echidnas, either...
intra-abdominal location (testicond). Primitive mammals, such as the monotremes (prototheria), also are testicond. Marsupial (metatheria) and placental...
for excreting liquid and solid wastes, for copulation and egg-laying. Monotreme mammals also have a cloaca, which is thought to be a feature inherited...
Teinolophos is a prehistoric species of monotreme, or egg-laying mammal, from the Teinolophidae. It is known from four specimens, each consisting of a...
penetrate the eggshell from inside and break free. Birds, reptiles, and monotremes possess egg teeth as hatchlings. Similar structures exist in eleutherodactyl...
resembles that of porcupines, which are rodents, and echidnas, a type of monotreme. The name hedgehog came into use around the year 1450, derived from the...
(2004 - At a Loss/Monotreme) Scream of the Iron Iconoclast (2007 - At a Loss/Monotreme) Sacrifice and Bliss (2009 - At a Loss/Monotreme) 7th Direction (2012...
This list of fictional animals contains notable fictional animals of species that do not have a separate list among either the lists of fictional animals...
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