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Author Topic: Why Does Roo Grow In The Pouch ?  (Read 3260 times)

Offline neilep

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Why Does Roo Grow In The Pouch ?
« on: 15/02/2008 14:01:22 »
Dear Kanga and other Pouch related Marsupial experts.

Why does baby kanga go live in a pouch ?...why not stay inside and get born ?....Is it to save the difficulty of birth ?

Here's mummy and baby:




and check this out......here the mother/baby pouch thing has gone too far !!



..at least.......that's what it looks like to me !! ::) ::)




Kan-ger-roo help me with the answer ?  *That's it....I've hit rock bottom*




















« Last Edit: 15/02/2008 14:10:40 by neilep »


 

Offline JimBob

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Why Does Roo Grow In The Pouch ?
« Reply #1 on: 15/02/2008 18:26:13 »
I think that is why Darwin wrote his book.

Mammals have been around since the Triassic and come into their own during the Paleocene. This is only known from bones so the reproductive techniques are not know. The mammals came from Therapsids reptiles. These mammal-like reptiles use two bones for hearing that all other amniote reptiels (crocodiles, etc) use for eating. There were many types of mammals that evolved during the Mesozoic (Triassic, Jurassic and Cretaceous) that didn't make it after the extincion event at the end of the Cretaceous.

There were at the beginning of the Paleocene - that time period just after the Cretaceous - 4 different types of mammals. These were placental, marsupials, monotremes and multituberculates, the last going extinct after the beginning of the Paleocene. All we know about them is that they had all had a different tooth morphology (tubercles are knobby growths)- as well as other differences - than any other mammalians.

The three surviving types of mammals show the range of advanced sexual reproductive techniques that span the animal kingdom. (Some small little critters, such as barnacles as mentioned in a contemporaneous thread by Dr. Beaver has some strange habits - http://www.thenakedscientists.com/forum/index.php?topic=13003.0 ) The Monotremes we know of are egg laying mammals and do not have a teat but an area of the skin that has milk glands. Kanga gives birth to what in other mammals would be called an embryo. This is a totally different reproductive strategy that allows for the survival of the mother in extreme conditions, such as those that existed in the Paleocene, because at any time before the "embryo" develops into an animal that can survive on its own it can self-abort the fetus very easily. This provides for the survival of the mature reproductive animal which can breed again. It is also a much less energy expenditure for the mother as compared to placental mammals. While being a very advantageous a placenta and growing another life inside the body is VERY energy consuming. It has it downside as well as it up side. The mother's life is in jeopardy much more than with an embryo in the pouch as the marsupial can at any time eject the fetus if necessary.

So Kanga is just a trial in the way to reproduce.

Did I cover the subject well enough for you, Your Highness?   
 

Offline Carol-A

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Why Does Roo Grow In The Pouch ?
« Reply #2 on: 15/02/2008 21:56:10 »
I just came back to reply to this question, but I really can't do better than Jim Bob!!
 

Offline neilep

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Why Does Roo Grow In The Pouch ?
« Reply #3 on: 15/02/2008 22:22:09 »
I just came back to reply to this question, but I really can't do better than Jim Bob!!

Of course you can !!!.....
 

Offline neilep

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Why Does Roo Grow In The Pouch ?
« Reply #4 on: 15/02/2008 22:26:32 »
This provides for the survival of the mature reproductive animal which can breed again. It is also a much less energy expenditure for the mother as compared to placental mammals. While being a very advantageous a placenta and growing another life inside the body is VERY energy consuming. It has it downside as well as it up side. The mother's life is in jeopardy much more than with an embryo in the pouch as the marsupial can at any time eject the fetus if necessary.

So Kanga is just a trial in the way to reproduce.

Did I cover the subject well enough for you, Your Highness?   



Actually ...Carol-A is right !!....that's an answer that has me submitting my awe in agog in-perpetuity !


THANK EWE JimBOb !!.....
 

Offline JimBob

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Why Does Roo Grow In The Pouch ?
« Reply #5 on: 16/02/2008 01:04:46 »
I learned this in school. Isn't it strange how long this stuff stays with you? There was another class of mammals include in the list I learned, making 5 but the endentatas, such as armadillos and ant eaters have been moved into placental mammal.

Thank you for the compliments, Neil and Carol A.

 

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Why Does Roo Grow In The Pouch ?
« Reply #5 on: 16/02/2008 01:04:46 »

 

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