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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 ...
This category contains articles about all taxa below the subclass/order Monotremata - the platypus, the echidnas, and extinct species which are only known via fossil evidence. Subcategories This category has the following 5 subcategories, out of 5 total.
Yinotheria is a proposed basal subclass clade of crown mammals uniting the Shuotheriidae, an extinct group of mammals from the Jurassic of Eurasia, with Australosphenida, a group of mammals known from the Jurassic to Cretaceous of Gondwana, which possibly include living monotremes. [3]
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 ...
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.
An example spangram with corresponding theme words: PEAR, FRUIT, BANANA, APPLE, etc. Need a hint? Find non-theme words to get hints. For every 3 non-theme words you find, you earn a hint.
Like its fellow monotreme the platypus, the short-beaked echidna has a system of multiple sex chromosomes, in which males have four Y chromosomes and five X chromosomes. Males appear to be X 1 Y 1 X 2 Y 2 X 3 Y 3 X 4 Y 4 X 5, [110] [111] while females are X 1 X 1 X 2 X 2 X 3 X 3 X 4 X 4 X 5 X 5.