Re: eggs with thin shells

[larrys@zk3.dec.com]

>The reason dinosaurs (and crurotarsians) retained their large tails has to
>do with the musculature associated with walking.  Whereas in the Synapsida
>(mammals included) and in primitve reptiles, the major "thrust" muscles for
>the femur attach to the hip, in the Diapsida (lepidosauromorphs and
>archosauromorphs) the major "thrust" muscle is the M. caudofemoralis.  As
>the name implies, it attaches on the femur and the tail (or at least the
>proximal part of the tail).

Okay.  I can see that.  Well...no...I _can't_ see that.  But I'll
take your word for it until I can find a picture to look at.

First multitubiculates, now M. caudofemoralis.  What a week.  You
can't help but get educated around here.  :)

>In a few dinosaurs (i.e., dromaeosaurids and birds), the was significant
>transformation of the hip and proximal tail region, and it is believed this
>is associated with a transformation of the locomotory muscles.

If this is the case, it would seem to me that any dinosaur group that
showed a diminution of the tail would be an important marker or signpost
on the way to birds, since birds have very little tail under all the
feathers.  How are bird muscles done?  Heaven knows I eaten a few, but
a don't recall much of the tuchis musculature...  And what dinosaurs
show smaller tails?

I still like the idea that dinosaurs had _other_ uses for the tails,
though - otherwise it seems to me they could still be a lot smaller...

regards,
Larry Smith