Re: Two tyrannosaur questions

["David Marjanovic" <david.marjanovic@gmx.at>]

> I've seen some life restorations of T. rex that depict an external
tympanic
> membrane, similar to what is seen in some amphibians.  This seems curious
to
> me, since reptiles and birds both (to my knowledge anyway) have an open
tube
> leading to an internal typanum. Isn't it more likely that T. rex (or even
> dinos in general) had an open ear tube rather than an amphibian-like
> external membrane over the ear canal?

I don't know any fossil evidence for or against that. I can only add that
monotremes, too, have an open ear tube. Your phylogenetic bracketing sounds
convincing.

> If a T. rex were
> standing still and holding its arms in a "relaxed" position, would its
palms
> more likely be facing the ground or facing inwards towards its midline?

Facing inwards towards each other, and it was unable to change that. See the
big paper in Mesozoic Vertebrate Life. The arms are selected for maximum
force and stability (while *Deinonychus* arms are selected for maximum speed
of the "predatory strike" and human arms are selected for maximum mobility).