theropod egg evolution

["Ken Kinman" <kinman@hotmail.com>]

Mickey,
    In your oviraptor-therizinosaur post, you said you believe prismatic
eggshells to be the primitive condition for avetheropods.  I think Gerald
Grellet-Tinner has also suggested this, but I don't think that is the only
way to look at it.
    It seems to me to be as likely (perhaps more so) that early
avetheropods had the typical primitive sphaerulitic eggshells, and that
prismatic is a transitional form between the primitive form and the fully
derived ornithoid form, and that prismatic could have easily arisen more
than once---- such as allosaurids (? don't recall such an assignment
offhand), and again in Troodontids (which do have definite "ornithoid"
relatives), and perhaps also convergently in Protoceratopsids (not sure
where the debate on that ended up).
    Perhaps another piece of evidence that Troodontids may well be
paraphyletic and/or transitional between ornithomimes and the "ornithoid"
taxa (oviraptors, deinonychosaurs, and birds).  Sure do wish we knew which
kind of eggshells were found in the eggs of Alvarezsaurus and mononykines.
    Anyway, does anyone know if Gerald Grellet-Tinner has published any of
his eggshell papers that are supposed to come out this year?  Those are the
ones I've been anxiously waiting for.
                ---------Ken
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