Chris,
the Hawaiian Islands belong to a tectonic plate which seems to be mowing
slowly: about 50 km in one million years.  Hence the position of the islands
changed in about 5 km  during the last 100,000-200,000 years. If the water
temperature around the Hawaiian Islands really changed, this event can be
explained by other factors. Besides, there is a hypothesis that certain
mollusc species grow larger in could water; this assumption can be confirmed
by the Hawaiian Cypraea tigris schilderiana and Mauritia maculifera
hawaiiensis but, on the contrary, shells of Pustularia cicercula takahashii
seem to be smaller than shells of P. cicercula in the Philippines and in
East Africa.
Also shells of closely related taxon: P. mauiensis are substantially
smaller.
Thank you for answering my question
Ed



----- Original Message -----
From: "Chris Takahashi" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, January 11, 2008 7:03 PM
Subject: Re: [CONCH-L] Pustulariafossil records


> Aloha Conchers,
> In Hawaii Pustularia takahashii started appearing in the fossil records at
> the 15ft level(roughly 150,000yrs ago). Same level where 2 endemic
> species, Conus kahiko & Strombus ostergaardi, disappeared. Commonly found
> at this level to present strata are Conus pennaceus & Cypraea maculifera
> hawaiensis. During this era the Hawaiian Islands were much closer to the
> Equator due to plate techtonics. One would think the North-Eastward plate
> movement towards colder waters might have have changed the local species.
> This means the water temperature gets colder as time goes on & some
> species may die-off while others establish themselfs.
>
> Look at Lambis chiragra. This species prefer warmer temperatures & was
> present in Hawaiian fossil records 150,000yrs ago. Today no chiragra
> occurs in Hawaii. Could the colder waters restrict veliger developement?
> Or could the location of the islands in comparison to the Equator limit
> the veliger range of dispersion & settlement from other Indo-Pacific
> Islands? One must also consider the ocean level 150,000yrs ago in Hawaii
> was 15ft higher before the last ice age. Also 1.5 million yrs ago small
> Midway Atoll was a large major mountaneous Hawaiian Island roughly where
> Oahu is today.                             CHRIS:)
>
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