[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: (fwd) Re: Mammals as a cause of Dinosaur extinction




On Sat, 20 Dec 1997, Dale wrote:

> > On Thu, 18 Dec 1997, Rob Meyerson wrote:
> >
> > > I would call this coincidence.  Take a look at your typical placental 
> > > from that time.  It did not have the jaws to become any serious threat 
> > > for young dinosaurs.  Actually, placental development seems to make
> > > more sense as a defence from dinosaurs like Troodon who actively hunted
> > them.
> >
> > How much evidence for this is there?--Its sounds like a
> > reasonable argument for placentalism(keep'em indoors 'till they can @
> > least run away to some extent), but i'd like to know how much support for
> > this there is in the paleo community...
> >
> > Thanks,
> >
> > ----Steve
> 
>      I have about a half pence I would like add...It seems to me that egg
> attrition would be a very strong incentive for holding on to the egg as long
> as possible,to eventually become a placental birth. environmental egg 
> attrition
>  should also considered.

This is precisely along the lines I was thinking of as a possible
evolutionary path for placentalism, but there are many beautiful theories
out there which don't hold up in reality, hence my query. It also seems
plausible given the other mechanisms of in-utero developmental
stalling/reversal that we know some mammals are capable of when
environmentally stressed. 

----Steve