Re: Dino sex?

[Adam Yates <zooamy@zoo.latrobe.edu.au>]

On Tue, 3 Mar 1998, Randy King wrote:

> Has the possibility of external fertilization of the eggs been explored?
> I don't think I've ever read anything on the possibility.

This would be impossible for dinosaurs. It is a safe bet that all
dinosaurs laid hard, calcitic shelled eggs. Extant dinosaurs (ie. birds)
do, members of the closest living outgroup (crocodylians) do, and we have
direct fossil evidence that a great many non-avian dinos did as well
(including examples from the "big three clades", ie ornithischians,
sauropodomorphs and theropods). Once a calcitic shell is laid down around
the egg (which in crocs and birds can only happen in the female
reproductive system) the egg is impermeable to sperm, rendering external
fertilisation difficult, to say the least. 

cheers 

Adam Yates