

Re: theropod-bird eggshells

Hi Ken,

In 1999 Kenneth Carpenter wrote a nice book called eggs, nests, and baby
dinosaurs. He writes on the Ornithoid Basic Shell Type:

"Eggs with a birdlike shell structure containing a distinct mammillary layer
and continuous layer; distinct shell units are not defined. The pore canals
are usually angusticanaliculate."

He goes on naming some families if the Ornithoid Basic Shell Type and writes
under the Elongatoolithidae Zhao, 1975: "The shell has the ratite
morphotype, meaning that it is very similar to that seen in the eggs of
ratite birds, Because theropod dinosaurs are closely related, Mikhailov (a
leading expert on fossil eggs) believes elongatoolithid eggs were laid by
theropod dinosaurs. Indeed, at least one of the theropods is Oviraptor based
on a partial embryonic skeleton found adhering to the inside of an
elongatoolithid shell fragment."

Under the family Laevisootithidae he writes: "Laevisoolithid eggs were laid
by enantiornithine birds and/or small theropods (Mikhailov, 1997.)"

So there is some evidence the Ornithoid Basic Shell Type eggs were laid by
theropods, but enantiornithine birds may have laid them as well.

Best wishes,

Fred Ruhe

At 13:16 17-07-2000 PDT, you wrote:
>     I'm trying to find more details about the "ornithoid" type of eggshell 
>which is supposedly shared by theropods and ratites (and neognath birds as 
>     Is this ornithoid structure pretty distinctive?  And if so, why don't 
>the dinosaurologists emphasize it more?  Have Martin or Feduccia ever 
>provided a counterargument to the eggshell evidence?
>                      -------Ken Kinman