eggshells, therizinosaurs & tyrannosaurs

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

    Thanks for the information.  Unfortunately our university doesn't have 
anything by Ken Carpenter except his 1990 book on dinosaur systematics.
    But so far, it sounds as though the "ornithoid" eggshell morphology is 
characteristic of primitive birds (including enantiornithines and living 
ratites) and the "non-avian" maniraptoran theropods (troodonts and 
oviraptors, and presumably dromaeosaurs by inference).
    Since Therizinosaurs have the primitive dinosauroid eggshells, this 
seems to support Sereno's exclusion of that group from Maniraptora.  If 
Sereno is correct in placing tyrannosaurs as the immediate outgroup of the 
Maniraptora (sensu stricto), then tyrannosaur eggshells could be primitive, 
ornithoid, or something in between (transitional).
    What are the odds that tyrannosaur eggs will be discovered anytime 
soon, and any guesses how big their eggs would be?  Maybe canteloupe-sized?  
Or if oblong, perhaps more like a very large potato?  Or am I thinking too 
small?
                       -------Ken Kinman

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