Difference between Prototheria and Theria are given below:

Prototheria

1. External ear on pinnae is absent.

2. Teeth are absent in the adult condition.

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3. Cloaca is present.

4. Mammary gland is present but nibble is absent.

5. Testes are abdominal.

6. Corpus collasm absent.

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7. Egg laying animals.

Theria

1. External ear pinnae are present.

2. Teeth are well developed.

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3. Cloaca is absent.

4. Mammary gland is present with nipple.

5. Tests are descending in to scrotal sac.

6. Urethra is common for vasa differentia and urinary bladders.

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7. Viviparous animals.