Question

Difference between prototheria metatheria eutheria

Answer 1

Here is the answer-


Difference between Prototheria, Metatheria and Eutheria

The mammals are defined are hairy quardrupeds. Their name refers to the milk secreting mammary glands in the females for sucking the young for sometimes after birth. The mammals have evolved from the mammals like reptiles like Dimetrodon in Triassic some 200 million years ago in the Jurassic period, before the first birds. There are 5000 species of living mammals known.  




Prototheria vs Metatheria vs Eutheria

Prototheria (Egg laying mammals)

1. Ear without pinna.

2. No nipple

3.No corpus callosum

4. Testes abdominal, no scrotum

5. Digestive and urinogenital tracts open out through cloaca and cloacal aperture.

6. No marsupial pouch

7. Oviparous

8. No placenta

Example of Prototheria: Duck billed platypus (Ornithorynchus anatinus), Anteater (Tachyglossus)


Metatheria (Pouched mammals or marsupials)

1. Ear with pinna

2. Nipples abdominal

3. No corpous callosum

4. Scrotum in font of penis

5. Digestive and urinogenital tracts open out by separate apertures that are controlled by a common sphincter muscle.

6. Marsupial pouch often present

7. Viviparous

8. Placenta small, intrauterine development brief, young extremely small and helpless, brought up in marsupial pouch, if present.

Example of Metatheria: Kangaroo (Macropus), Opossum (Didelphis)


Eutheria (Placental mammals)

1. Ear usually with pinna.

2. Nipples abdominal or throracic.

3. Corpus callosum present.

4. Scrotum behind penis.

5. Digestive and urinogenital tracts open out by separate apertures, each with its own sphincter muscle.

6. No marsupial pounch

7. No marsupial pouch

8. Placenta large, intrauterine development prolonged, young advanced and fully formed.

Example of Eutheria: Rat(Rattus), Horse (Equus)

Answer 2

✌️✌️hey mate,

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➡️Prototheria:

1. They are OVIPAROUS.
2. Ear is devoid of pinna .
3. Scrotum is absent in male.
4. Vagina and uterus are absent.
5. Nipples are absent over the mammary gland.
e.g.,
•Echidna,
•Tachyglossus,
•Ornithorhnchus.

➡️Eutheria:
1. They are ViViPAROUS.
2. pinna is present except in aquatic forms.
3. the scrotum is present on the sides and behind the penis.
4. they are single structure.
5. nipples are present.

➡️Metatheria:
1. They are ViViPAROUS.
2. ear possess a pinna.
3. scrotum is present but infront of penis.
4. both vagina and uterus are double.
5. Nipples are present.

e.g.,
•Macropus,
•Didelphis.
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