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Monotremes (/ ˈ m ɒ n ə t r iː m z /) are mammals of the order Monotremata. They are the only 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 ...
The class Mammalia is divided into two subclasses based on reproductive techniques: egg-laying mammals (yinotherians or monotremes - see also Australosphenida), and mammals which give live birth . The latter subclass is divided into two infraclasses: pouched mammals ( metatherians or marsupials ), and placental mammals ( eutherians , for which ...
Dolphins have evolved electroreception in structures different from those of fish, amphibians and monotremes. The hairless vibrissal crypts on the rostrum of the Guiana dolphin (Sotalia guianensis), originally associated with mammalian whiskers, are capable of electroreception as low as 4.8 μV/cm, sufficient to detect small fish. This is ...
Ornithorhynchoidea is a superfamily of mammals containing the only living monotremes, the platypus and the echidnas, as well as their closest fossil relatives, to the exclusion of more primitive fossil monotremes of uncertain affinity.
However, the five species of monotreme, the platypuses and the echidnas, lay eggs. The monotremes have a sex determination system different from that of most other mammals. [2] In particular, the sex chromosomes of a platypus are more like those of a chicken than those of a therian mammal. [3]
Download as PDF; Printable version; In other projects Wikimedia Commons; Wikisource; ... List of monotremes and marsupials; List of monotremes and marsupials of ...
The class Mammalia is divided into two subclasses based on reproductive techniques: monotremes, which lay eggs, and therians, mammals which give live birth, which has two infraclasses: marsupials/metatherians and placentals/eutherians. See List of monotremes and marsupials, and for the clades and families, see Mammal classification ...
Prototheria (/ ˌ p r oʊ t ə ˈ θ ɪər i ə,-t oʊ-/, PROH-toh-THEER-ee-ə; [1] from Ancient Greek πρώτος prṓtos "first" and θήρ thḗr "wild animal") is an obsolete subclass of mammals which includes the living Monotremata and to which a variety of extinct groups, including Morganucodonta, Docodonta, Triconodonta and Multituberculata, have also been assigned.