User talk:Marshallsumter/Keynote lectures (draft)/Ammonoids

=Ammonites= Yes, an ammonoid is an extinct cephalopod mollusk and some but not all have a flat-coiled spiral shell. Moreover not all cephalopods with falt coiled spiral shells are ammonoids. Ammonoids, which refers to the subclass Ammonoidea, are shelled cephalopods that lived from the Devonian period of the Late Paleozoic to the end of the Cretaceous, at the end of the Mesozoic, unified by convex septa, sutures of varying complexity, and septal necks that commonly point forward (prochoanitic), distinguishing them from the Nautiloidea.

True, an ammonite may belong to the Ammonitida, characterized by eleaborate sutures, but may also belong to any of the other orders with equally or less elaborate sutures.

Information under Mollusks and Cephalopods could be included in the "Anatomy" section,  with more gneral characters inferred from the Mollusca and more specific from the Cephalopoda. The manlte is not a cavity, it is a membrane that secretes the shell and forms the mantle cavity which houses the visceral organs.

And finally, to top this off, is there really such a thing as a theoretical ammonite? I don't think so.. There may be the theory of ammonite evolution and there may be ambiguous ammonites that could as well be included in their ancestral Bactritida. ‎Furasta

=Flat-coiled spiral shells=

Some fossils from Japan are anything but flat-coiled spiral shells. I believe the inclusion of the phrase "flat-coiled spiral shell" is a bit of an over-generalization. --Marshallsumter (discuss • contribs) 00:09, 27 April 2015 (UTC)

=Ammonoids=

I haven't found a definition of "ammonoids" yet but it does make sense that it means members of the Ammonoidea. What I'm looking for is a term that means "a cephalopod with an external shell". Some of the articles in the literature that I've read so far use "ammonoids" but do not directly tie it to the Ammonoidea nor actually define it. What do you think about our using "ammonoid" as a word meaning "a cephalopod with an external shell"? --Marshallsumter (discuss • contribs) 04:48, 20 April 2015 (UTC)

=Devonian to Cretaceous end=

I have found one source (Simm) so far that suggests that ammonoids did occur during the early Tertiary. --Marshallsumter (discuss • contribs) 00:09, 27 April 2015 (UTC)

=Convex septa, sutures and septal necks=

I think I have a definition of prochoanitic septal necks. --Marshallsumter (discuss • contribs) 00:09, 27 April 2015 (UTC)

=Mantles=

The phrase is "a mantle with a cavity for breathing and excretion". This differs from "The manlte is not a cavity,". Wiktionary has a nice definition of mantle which corroborates your description. --Marshallsumter (discuss • contribs) 04:48, 20 April 2015 (UTC)

=Theoretical ammonites=

I have added more cited information about a theory of ammonites, or a theory of ammonoids. --Marshallsumter (discuss • contribs) 16:15, 15 April 2015 (UTC)

=Nautiloids and non-Ammonites=

I have inserted some text indicating that there are other shelled cephalopods that are not or may not be ammonoids. Does this read better than "Not Ammonites"? --Marshallsumter (discuss • contribs) 00:09, 27 April 2015 (UTC)