placental mammal

placental mammal

      any member of the mammalian group (cohort Placentalia) characterized by the presence of a placenta, which facilitates exchange of nutrients and wastes between the blood of the mother and that of the fetus. The placentals include all living mammals except marsupials (marsupial) and monotremes (monotreme). Although some authorities consider the marsupials (cohort Marsupialia) to be placental mammals, these animals have a less-developed, less-efficient type of placenta that limits the gestation period. The true placenta of the placentals allows for a longer developmental period within the protection of the womb, a factor considered to have contributed to the evolutionary success of the group.

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  • placental mammal — n any mammal of the major taxonomic division Eutheria characterized by the attachment of the developing fetus to the maternal uterus by a placenta …   Medical dictionary

  • placental mammal — noun mammals having a placenta; all mammals except monotremes and marsupials • Syn: ↑placental, ↑eutherian, ↑eutherian mammal • Derivationally related forms: ↑placental (for: ↑placental) …   Useful english dictionary

  • Placental — Pla*cen tal, a. 1. Of or pertaining to the placenta; having, or characterized by having, a placenta; as, a placental mammal. [1913 Webster] 2. (Zo[ o]l.) Of or pertaining to the Placentalia. [1913 Webster] …   The Collaborative International Dictionary of English

  • Mammal — For other uses, see Mammal (disambiguation). Mammals Temporal range: Late Triassic – Recent, 220–0 Ma …   Wikipedia

  • mammal — mammallike, adj. /mam euhl/, n. any vertebrate of the class Mammalia, having the body more or less covered with hair, nourishing the young with milk from the mammary glands, and, with the exception of the egg laying monotremes, giving birth to… …   Universalium

  • Mammal classification — Over 70% of mammal species are in the orders Rodentia (blue), Chiroptera (red), and Soricomorpha (yellow) Mammalia is a class of animal within the Phylum Chordata. Mammal classification has been through several iterations since Carolus Linnaeus… …   Wikipedia

  • placental — I noun mammals having a placenta; all mammals except monotremes and marsupials • Syn: ↑placental mammal, ↑eutherian, ↑eutherian mammal • Hypernyms: ↑mammal, ↑mammalian …   Useful english dictionary

  • placental — Relating to the placenta. * * * pla·cen·tal əl adj 1) of, relating to, having, involving, or produced by a placenta <placental lactogen> <placental defects> 2) of or relating to placental mammals placental n PLACENTAL MAMMAL * * *… …   Medical dictionary

  • placental — I. adjective Date: 1791 1. of, relating to, having, or occurring by means of a placenta 2. eutherian II. noun Date: 1839 a placental mammal ; eutherian …   New Collegiate Dictionary

  • placental — adjective relating to a placenta. ↘Zoology relating to or denoting mammals that possess a placenta; eutherian. noun Zoology a placental mammal …   English new terms dictionary

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