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Re: please share your knowledge

>From: supercalafragilisticexpialadocious <kilraika@bigvax.alfred.edu>
 > BTW, what is the notochord in the Cambrian??? 

A notochord is a particular anatomical structure found in embryonic
vertebrates, tunicates, and a few other obscure groups.  It is a
cartiligenous bar along the dorsal midline, immediately interior
to the nerve chord. In those animals that have one in a free-living
stage of life, it provides an elastic base against which locomotory
muscles can operate.  (In vertebrates, it is *replaced* by the
centra of the vertebral column).

The earliest known fossils with clear evidence for a notochord
are from the Cambrian Period.  The most spectacular of these fossils
closely resembles the living chordate _Amphioxus_.  In addition,
it is now known that the conodont animal was a chordate.

[Chordate means "an animal with a notochord"].

swf@elsegundoca.attgis.com              sarima@netcom.com

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