Extinct Phyla?

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

Paul Ciszek - 30 Oct 2007 19:10 GMT

If, as some claim, all of the "weird wonders" of the Burgess Shale
can be shoehorned into existing phyla, then are there any extinct
animal phyla?

Since the the phylum--possibly even the kingdom--of the Edicara are
in dispute, let's leave them out of it for now.

Signature

Please reply to: | "One of the hardest parts of my job is to
pciszek at panix dot com | connect Iraq to the War on Terror."
Autoreply is disabled | -- G. W. Bush, 9/7/2006

Reply to this Message

John Harshman - 31 Oct 2007 03:44 GMT

> If, as some claim, all of the "weird wonders" of the Burgess Shale
> can be shoehorned into existing phyla, then are there any extinct
> animal phyla?

This is not an objectively determinable question, since phyla themelves
are subjective entities. Whether you want to call some group a phylum, a
class, or Billy Bob is up to you, and there are no scientific criteria
that can tell you where on the tree to put the cutoff points. Are
anomalocariids a group of primitive arthropods, or are they the sister
group of arthropods? Depend on how you want to define "arthropod".

But there are a number of Cambrian fossils that can't be assigned with
any confidence to living phyla, and some that may be equally closely
related to multiple extant phyla, making them phyla by default if so.
Halkieriids, Dinomischus, and archaeocyathids are good candidates.

> Since the the phylum--possibly even the kingdom--of the Edicara are
> in dispute, let's leave them out of it for now.

Reply to this Message

Natural Science Forum / Biology / Paleontology / October 2007

Extinct Phyla?