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Paired Eggs in a Dinosaur Indicate Biological Sex

... and support Norell's contention in 1993 that *Citipati* had paired oviducts
used in series to lay rings of eggs.

Sato T., Cheng Y.-N., Wu X.-C., D. K. Zelenitsky, and Hsiao Y.-F. 2005. A Pair
of Shelled Eggs Inside A Female Dinosaur. _Science_ 308[5720]:375-376. (w/ supp

  "An oviraptosaurian specimen (Dinosauria, Theropoda) from an Upper Cretaceous
   formation in China retains a pair of shelled eggs in the pelvis, providing
   direct evidence that oviraptorosaurian dinosaurs laid paired elongatoolithid
   eggs. The presence of the paired eggs suggests that theropod dinosaurs had
   two functional oviducts (like crocodiles) but that each oviduct produced
   one egg at a time and that an entire egg clutch was laid through multiple
   ovipositions (like birds). The orientations of the eggs inside the skeleton
   and in clutches indicate that the mother came to the center of the nest to
   lay eggs."

  The specimen is very incomplete, comprising the lower pelvic canal, but it's
indications for oviposition are clear both from fossil nests and the pairing of
eggs in those nest and in this specimen. The relatively intact though crushed
eggs within the pelvic canal indicate without much room for doubt the sex of
the dinosaur, for the first time.


Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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