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Re: Time Line
- To: firstname.lastname@example.org
- Subject: Re: Time Line
- From: email@example.com (Bob Myers)
- Date: Wed, 7 Sep 1994 14:58:43 -0700
- In-reply-to: Stan Friesen <swf@ElSegundoCA.NCR.COM> "Re: Time Line" (Sep 7, 17:08)
- Organization: Unocal Exploration and Seismic Technology
On Sep 7, 17:08, Stan Friesen wrote:
} Subject: Re: Time Line
> > > First rudists
> An early group of corals, rather different than the living hexacorals.
Um, no. The rudists were reef-building mollusks (clams). Not corals at
all, but a similar niche (reef-builder).
> > > First grazing echinoids
> Echinoids are starfish, sea-lilies, sea-cucumbers, sea-urchins
> and so on. The earliest ones were rather like sea-lilies, and
> probably were what is known as filter feeders (a "passive" sort
> of feeding). Later forms, including most living forms, use a
> more active form of feeding, involving searching for food - that
> is the "grazing" forms and the even more derived carnivorous
> forms, such as starfish.
> [Ack, or are echinoids a *sub*group of the echinoiderms??].
Yes, the echinoids are a subgroup of the echinoderms.
The echinoids are sea urchins and sand dollars. Echinoderms, but only a
sub-group thereof. Starfish, sea lilies (crinoids), sea cucumbers, etc.,
are all echinoderms, but not echinoids.
I suspect you're right that echinoderms were meant originally, though.
"First grazing echinoderms" seems to make more sense than "first grazing
Bob Myers Unocal Information Systems Support
Internet: Bob.Myers@st.unocal.com P. O. Box 68076
Phone:  693-6951 Anaheim, California 92817-8076