Re: Origin of body plans (phyla)
David Campbell (bivalve@mailserv0.isis.unc.edu)
Fri, 23 Oct 1998 10:45:22 -0400
>The key phrase I used was "mineralised skeletons". Many crustaceans lack
>mineralised skeletons, but get by very well with chitinous ones. My
>understanding of the trilobite skeleton was that it consisted of chitin
>mineralised by calcite. Trilos that whose skeleton was not mineralised would
>still function, but would not leave a fossil record.
In places with exceptional preservation, there are trilobite-like animals
without mineralized skeletons (Naroia, etc.). Also, only the top of
trilobites is mineralized. The legs of later trilobites are unmineralized,
yet left perfectly good traces.
David C.