Re: Re:Tyrannosaurus eggs

[Tom Holtz <tholtz@geochange.er.usgs.gov>]

>>No, all the elongate eggs previously assigned to Protoceratops are now
>>assigned to theropod dinosaurs.  Probable Protoceratops eggs have long
>been
>>known, but are a different morphology.
>
>Sorry, Tom, but some of the elongated eggs may indeed be those of
>Protoceratops.  The surface has
>similar lineartuberculate nodes, but the ultrascruture of these eggs is
>prismatoolithic, whereas the Oviraptor
>egg is avian.  Might the similar surface texture be convergence or
>Batsean mimicry?

Oops.  You are, of course, correct here.  I might add that Tony Thulborn,
in a 1992 paper (Nest of the dinosaur _Protoceratops_, Leithia 25:145-149)
described how the eggs traditionally interpreted as protoceratopsian
(somewhat conical, with opposite poles of differnt curvature) are probably
not from Protoceratops.  What he considered true Protoceratops eggs are
nearly isopolar (both ends of the same curvature).

I believe that the recent Oviraptor finds conform to the first type of egg.
Unfortunately, none of the protoceratopsian embryos discussed in the
Canadian Journal of Earth Sciences Sino-Canadian Expedition volume could
confidently be associated with egg shells or eggs, so we still don't know
what exactly a valid Protoceratops egg looks like.

>> Since these eggs resemble
>>those known from other coelurosaurs (Oviraptor, Velociraptor),
>
>Sorry, no definite Velociraptor eggs known.

Should've put that question mark before "Velociraptor".  In the Norell et
omnia paper in Science describing the Oviraptor eggs, they note that the
"juvenile" Velociraptor skulls may be from embryos, not hatchlings.  They
consider several hypotheses, amont them the ideas that Oviraptor or
Velociraptor were cukoo-like nest parasites or that some of the nearby nest
sites (for which embryos are not yet known) may be dromaeosaurid, not
oviraptorid.

                                
Thomas R. Holtz, Jr.                                   
tholtz@geochange.er.usgs.gov
Vertebrate Paleontologist in Exile                  Phone:      703-648-5280
U.S. Geological Survey                                FAX:      703-648-5420
Branch of Paleontology & Stratigraphy
MS 970 National Center
Reston, VA  22092
U.S.A.