Talk:Rayonnoceras

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paragraph about Actinocerid history

This paragraph about actinocerid evolution seems out of place:

"Originating in the Ordovician, by the Devonian period Actinocerids became rare; perhaps they were unable to compete with the more compact and maneuverable coiled nautiloids and ammonoids and cope with the arrival of jawed fish. Rayonnoceras was among the last of the actinocerids, which finally died out in the Carboniferous."

These details had more relevance when Rayonnoceras and other carbactinoceratids were classified as actinocerids. My inclination is to move the paragraph to the Actinocerida article, but of carbactinoceratids are pseudorthocerids, then even this may only be a footnote of historical interest. Any thoughts? Cephal-odd (talk) 05:35, 13 September 2009 (UTC)[reply]

Habit

Rayonnoceras, especiall; larger adults, were most likely bottom dwellers, ambush preditors and were not swimmers in any sense like squid or fish. The large, heavy, rigid shell would have been too much of an impediment for such a habit. There is no reason to equate them with squid, other than they perhaps had 10 arms or tentacles. Since they are not part of the direct line that lead to belemnites and coleoids (along with ammonites) there is no reason to conclude they died with in a 3 or 4 year lifetime after mating and laying eggs for the first time. They are phylogenetically probably just as close and possibly closer to Nautilus than they are to squid and octopods. Nautilus lay broods of eggs annually once reaching sexual maturity after several years and live anywhere from 15 to 20 years. [1] There is no reason to assume Rayonnoceras did not do the same. Regards to all you cephalophiles J.H.McDonnell (talk) 02:39, 13 December 2009 (UTC)[reply]