RE: Macroolithus

[GUNTER.VANACKER@ELECTRABEL.COM]

You are probably refering to this message :

http://www.cmnh.org/fun/dinosaur-archive/2001Jul/msg00141.html

The dendroolithid oofamily was explicitly assigned to therizinosaurs (with
some reservation).

I don't have any references at hand, but both the oogenus Macroolithus an
Macroelongatoolithus are (like Elongatoolithus) part of the largest oofamily
Elongatoolithidae, which includes quite diverse types of dinosaur eggs, but
all are referable to advanced theropods. The oogenus Protoceratopsovidum
(like the name indicates previously referred to "protoceratopids") shares
many characters with Elongatoolithidae and should probably be placed in the
same oofamily. I believe that only a few eastern European workers still
maintain that this oogenus is referable to "protoceratopids". The large
number of oospecies in Elongatoolithidae (and their individual variation) is
one of the main reasons why I think that this oofamily is not only referable
to oviraptorids but is the basal egg configuration for a larger clade
(Maniraptora).

We still have no positive identification of embryonic remains for the
oogenus Macroelongatoolithus.
This genus was mainly based on the oospecies Macroelongatoolithus
xixiaensis, from the Cretaceous of Xixia County, Henan province, China. This
is the famous site that yields thousands of dinosaur eggs that represent
many oogenera (Elongatoolithidae, Dendroolithidae, Spheroolithidae ...),
most of the dinosaur eggs that are on sale (mineral shows, the Internet ...)
are from this locality. The exact age of this site is uncertain; it has been
suggested as early Cretaceous or even late Late Cretaceous (ranging from 130
to 65 MYA).

Recently (Journal of Vertebrate Paleontology, March 2000 issue),
Macroelongatoolithid eggshell was reported from the early Cretaceous Cedar
Mountain Formation of Utah. The eggshell fragments appear identical to M.
xixianensis from China; this may prove that the Chinese eggs were also early
Cretaceous.
Since Deinonychus eggshell is now known to closely resemble elongatoolithid
eggshell (and probably belongs in this family), I suggested that some of the
abundant elongatoolithid oospecies may have been produced by dromaeosaurids,
and not only oviraptorids.
Wouldn't Utahraptor ostrommaysorum, which is from the same Cedar Mountain
Formation, be a very likely candidate for the M. carlylei (= M. xixianensis,
Zelenitsky, Carpenter & Currie, 2000) eggshell fragments ?  The size of the
Cedar Mountain eggs is estimated at 38+ cm (15").
In the paper mentioned above, Microvenator celer is suggested as the species
that produced the North American Macroelongatoolithus eggs. It is unlikely
that the basal oviraptorosaur Microvenator grew to about 6m (20ft), which is
a realistic size for an animal that produced these large eggs. Since
publication of the paper, dromaeosaurs are now also likely to have produced
this type of egg, and Utahraptor fits the necessary size perfectly.



Regards,
Gunter Van Acker



-----Oorspronkelijk bericht-----
Van: kelly bell [mailto:kellbell75704@yahoo.com]
Verzonden: dinsdag 10 juli 2001 4:16
Aan: dinosaur@usc.edu
Onderwerp: Macroolithus


Several weeks ago someone suggested the
Macroolithus egg variety was laid by a therizinosaur.
This is dubious, as the more round dendroolithus egg
type is attributable to therizinosaurs (see
Mikhailov.)  Formerly the Macroelongatoolithus eggs
(similar to Macroolithus) were thought to have been
laid by a therizinosaur, until the associated
embryonic remains were identified as oviraptorsaurid.

Kelly Bell



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