[Flipside]

http://www.bbc.co.uk/news/science-environment-14447187

A recent fossil finding of a Plesiosaur with a semi-developed foetus inside it pretty much confirms the suspicion that, similar to the Whale, Plesiosaurs gave birth to live young.

Whilst not an Earth-shattering discovery (I remember reading some years ago that the skeletal structure of the plesiosaur suggested live-birth), I find it interesting because it helps to highlight the fact that Dinosaurs were not the only branch of the reptillian tree on Earth during that period.

[Grizzly]

, I find it interesting because it helps to highlight the fact that Dinosaurs were not the only branch of the reptillian tree on Earth during that period.

Aren't animals who give birth to live young not reptelians, but mammals?

[pecenipicek]

as far as i know my "biology", mammals are only animals that actually nurse their offspring via milk or such.

[Flipside]

The definition used to include giving birth to live young, but since there have been reptiles found that give birth to live young (though through a slightly different process that is sort of halfway between egg-laying and womb-gestation) , It's more about warm blood and, as Pece says, suckling their young.

For example, Garter Snakes give birth to live young, but that is because the egg remains inside the body and hatches there.

[Mongoose]

Nature's egg-laying grab-bag the platypus (Perry!) qualifies as a mammal too.

[StarSlayer]

Could be a xenomorph 

[Black Wolf]

Two species of echidna in Monotremata as well (i.e. Egg laying mammals ).

[EDIT]My bad, two genuses (genii?), 4 species

[Mongoose]

Genera, actually.  I'd still like to slap whoever first started that "-ii" suffix debacle, as very few Latin words use it.