प्रोटोथीरिया एवं मेटाथीरिया में कोई तीन अन्तर लिखिए।
Answers
Answer:
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)
ii. 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)
iii. 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)
Explanation: