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Re: Psittacosaurus adult found with 34 juveniles



> As for elevated metabolic rates; given the lack of LAGs and the large
> eyes, it seems as if they were adapted to toughing out the dark winter
> months. The theropod Timimus from the same area has quite pronouced
> LAGs. I like to think of hypsies as being like the polar-nesting bird
> equivalent of the Cretaceous (think flightless geese). If many theropods
> were unable to handle the most severe of winter conditions, then
> sticking around at those times would have been a great predator
> avoidance strategy for the hypsies.

However... in extant (tropical) crocs, LAGs are endogenous. The animals make
them even when reared under constant temperatures.

> Perhaps live-birth for some polar hypsies was not out of the question?

I personally suspect that live birth is not possible for archosaurs because
the embryo gets its calcium from the eggshell. There are live-bearing
geckos, however, while other geckos have hard eggshells. Does someone know
if those shells are a necessary calcium source, too?