I don't think it is a fossil lamprey

[Ken Kinman]

John,
    I took a quick look at the Nature article, and I also think Xidazoon is
probably an invertebrate.  I immediately thought of Class Anomalocarea
(Phylum Arthropoda).  It is interesting to note that Class Priapulea is
seriously being considered as a relative of arthropods, both genetically and
morphologically.  So perhaps this form belongs somewhere between priapulids
and anomalocarids (perhaps they all belong in Phylum Protarthropoda, with
tardigrades and walking worms).  Who knows.  Fascinating stuff though.
       I'll have to look into a possible affinity with Order Coronatida
(Class Scyphozoea, Phylum Cnidaria).  I don't work on jellyfish very often,
so not very familiar with them.
      As for it's possible affinities to Class Agnathea (Phylum Chordata),
I'll have to ponder that when I have more time.  The enigmatic fossil
Ainiktozoon was thought to be a primitive chordate for a long time, but
turned out to be an arthropod (and therefore transferred to the extinct
Class Thylacocephalea---a really weird bunch of critters).
------Ken Kinman
P.S.  Can't rule out spoonworms either, since they did note a resemblance to
Banffia (a possible spoonworm relative).
****************************
>From: John Bruner <jbruner at GPU.SRV.UALBERTA.CA>
>Shu, D., Morris, S. Conway, Zhang, X-L., Chen, L., Li, Y., and Han, J.
>1999.  A pipiscid-like fossil from the Lower Cambrian of south China.
>Nature Vol. 400 (6746):746-749.
>
>I have a question concerning the paper on the *Xidazoon stephanus* Shu,
>Morris, and Zhang, 1999.  Did anyone else who read the paper immediately
>think that it might be a member of the Phylum Priapulida (formerly in the
>Phylum Aschelminthes) or a member of the Phylum Sipuncula?  As soon as I
>saw the picture of the fossil, it reminded me of *Priapulus bicaudatus*.
>Also, the authors did not discuss the scyphomedusae Order
>Coronatida, which is known from the Lower Cambrian and has some resemblance
>to the "mouth". The Polish Eocene  fossil *Lorenzinia carpathia* has been
>put in the Order Coronatida and resembles the *Xidazoon stephanus*'s
>"mouth".  I have examined all the "pipiscid-like" Pennsylvanian Francis
>Creek Shale lampreys at the Field Museum in Chicago and my take on *X.
>stephanus* is that it looks like an
>invertebrate to me.  But, I am no expert on invertebrates and do not
>pretend to be.
>
>         John
>******************************************************
>* Mr. John C. Bruner                                 *
>* Department of Biological Sciences                  *
>* Unviersity of Alberta                              *
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