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Home > Science > What is the Difference Between Prototheria Metatheria and Eutheria?

Guilherme Mazui

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What is the Difference Between Prototheria Metatheria and Eutheria?

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The difference between Prototheria, Metatheria, and Eutheria lies in their reproductive systems and the development of their offspring. These three groups are subclasses of mammals, each with distinct characteristics:

  1. Prototheria: This subclass includes egg-laying mammals, such as the platypus and echidna. Prototherian mammals are the most primitive and lack a true placenta.
  2. Metatheria: This subclass comprises marsupial mammals, such as kangaroos and opossums. Metatherians give birth to live but partially developed young ones, which then complete their development in a pouch. They have a simple placenta for providing nutrients to the developing embryo.
  3. Eutheria: This subclass includes true placental mammals, such as humans and bats. Eutherians give birth to well-developed young ones, having a placenta that provides oxygen and nutrients to the growing embryo and helps in removing waste from the fetus's body.

In summary, the main differences between Prototheria, Metatheria, and Eutheria are:

  • Prototheria includes egg-laying mammals.
  • Metatheria includes marsupials with a simple placenta.
  • Eutheria includes true placental mammals with a well-developed placenta.
On this page
  • What is the Difference Between Prototheria Metatheria and Eutheria?
  • Comparative Table: Prototheria Metatheria vs Eutheria

    • Comparative Table: Prototheria Metatheria vs Eutheria

    Here is a table comparing the differences between Prototheria, Metatheria, and Eutheria:

    Feature Prototheria Metatheria Eutheria
    Reproduction Oviparous Viviparous Viviparous
    Ear No pinna Pinna present Pinna present
    Nipples No nipples Abdominal nipples Abdominal or thoracic nipples
    Corpus Callosum Small or absent Small or absent Large and well developed
    Cloaca Digestive and urinogenital tracts open into a cloaca Digestive and urinogenital aperture open into a shallow cloaca Digestive and urinogenital tracts open out by separate apertures
    Marsupial Pouch No pouch Often present Absent
    Testes No scrotum In front of penis Present
    Placenta Absent Less developed Well developed
    Group Examples Monotremes Marsupials Placental mammals

    Prototheria includes egg-laying mammals, such as monotremes. Metatheria includes marsupials, and Eutheria includes placental mammals that give birth to well-developed young ones.

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    Guilherme Mazui

    Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.