Re: Why the ammonites?

["David Marjanovic" <david.marjanovic@gmx.at>]

----- Original Message -----
From: "dinotracker" <dinotracker@earthlink.net>
Sent: Monday, June 03, 2002 5:47 AM

>     How is it that ammonites became extinct as a result of the K/T impact,
> when nautiloids did not?
>
>     According to the author of the fascinating book, THE GREAT DYING,
whose
> name I cannot recall off hand, the egg casings of ammonites were primarily
> calcium carbonate, while the egg casings of nautiloids were primarily
> magnesium carbonate. [...]

Interesting. What I've read (forgot where) is that ammonites had planktonic
larvae (do we know that, actually?), while nautiloids don't, and the
plankton was decimated while deeper-sea K-strategists like nautiloids
weren't.