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Re: Beipiaosaurus and sauropod ancestry
> In a message dated 6/21/99 0:12:20 AM EST, email@example.com writes:
> << Really, it appears to be a weight-related feature, but hopefully this
> be clarified by further study >>
> Don't think it's weight-related. Alxasaurus is a far smaller animal than
> Tyrannosaurus, yet Alxasaurus shows the segnosaurian foot whereas
> Tyrannosaurus has a typically theropodan (albeit massively built, of
> foot with highly reduced first toe. If it were purely a weight issue, one
> would expect tyrannosaurids and many other large theropods to show
> segnosaurian readaptation of the first toe.
> -T. Michael Keesey replied
> Perhaps it's a graviportal issue?
As far as I know there's a discussion going on about what therizinosaurids
fed on. If therizinosaurids were theropods then they would have had to adapt
to their new way of feeding (whatever it was, e.g. herbivorous, omnivourous).
That would include some anatomical adaptions, resulting perhaps in a shifting
of their center of mass.
Or the segnosaurian readaptation of the first toe simply happened (among
other things) because that way therizinosaurids were better adapted for
reaching their food.
Heinz Peter Bredow