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During the course of evolution, the monotremes have lost the gastric glands normally found in mammalian stomachs as an adaptation to their diet. [37] As such, by some definitions, they do not have stomachs as an organ, [38] although the term is widely used in studies of monotreme anatomy. [39] [40] Monotremes synthesize L-ascorbic acid only in ...
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 ...
Platypuses may have some duck-like characteristics, but they are a rare type of mammal called a monotreme. Monotremes differ from other mammals because they lay eggs instead of giving birth.
Echidnas are possibly named after Echidna, a creature from Greek mythology who was half-woman, half-snake, as the animal was perceived to have qualities of both mammals and reptiles. [citation needed] An alternative explanation is a confusion with Ancient Greek: ἐχῖνος, romanized: ekhînos, lit. 'hedgehog, sea urchin'. [5]
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. [1]
Crown-group Mammalia - the group that contains most recent common ancestor of monotremes and therians and all of its descendants. This group is defined by additional characters relating the occlusion of molars and the presence of a well-developed masseteric fossa. Australosphenida - a clade that contains monotremes and their
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] The mammary glands of mammals are specialized to produce milk, a liquid used by newborns as their primary source of nutrition.
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 ...