[Taxacom] Cambrian problematic "genus" Opabinia (my larval hypothesis)

[Kenneth Kinman]

Hi Mario,
        Thank you for the weblink to the preprint.  It is quite an interesting article.  The fact that the new opabiniid was previously identified as an anomalocaridid would seem to add some more weight to my larval hypothesis.  I have written to the first two authors of the article.
        As for the proboscis, there are no annulations preserved in this new opabiniid specimen.  However, Opabinia specimens do show annulations in the proboscis, and I think such annulations could probably become deeper during metamorphosis to form the segments of an Anomalocaris frontal appendage.
                            -------------Ken

________________________________
From: Taxacom <taxacom-bounces at mailman.nhm.ku.edu> on behalf of Mario Schädel via Taxacom <taxacom at mailman.nhm.ku.edu>
Sent: Wednesday, April 28, 2021 8:28 AM
To: taxacom at mailman.nhm.ku.edu <taxacom at mailman.nhm.ku.edu>
Subject: Re: [Taxacom] Cambrian problematic "genus" Opabinia (my larval hypothesis)

Dear Kenneth,

first of all I would like to point you towards this preprint:
https://www.biorxiv.org/content/10.1101/2021.03.10.434726v1.full

Second, I would like to express my concerns regarding your hypothesis.
In order to be a likely hypothesis, your hypothesis should be able to
explain how such a dramatic morphological change can happen. Assuming
your hypothesis to be true, one would assume to find homologous
structures in the larva and the adult. In Anomalocaris the large
anterior appendages consist of multiple elements. Yet, in Opabinia there
seems to be no trace of individual elements. Maybe you should contact
the authors of the preprint, that I've put above and ask them, if they
have seen structures that would support your hypothesis.

Best wishes,

Mario


On 4/28/21 2:11 PM, Kenneth Kinman via Taxacom wrote:
> Hi All,
>         I was reading a 2015 article about "genus" Opabinia by Derek Briggs, but it seems to be a commentary and summary about the history of research on Opabinia, rather than offering any new information.  I wonder if there is anything published more recently.
>         After 20 years, I still believe that Opabinia is likely a synonym of Anomalocaris--- either a larval form of Anomalocaris or possibly a dwarf male of Anomalocaris.  I think my larval hypothesis is most likely, since the largest Opabinia is around the same size as the smallest Anomalocaris (about 3 inches).  During metamorphosis, the long "proboscis" of Opabinia would have simply split into the two frontal appendages of Anomalocaris.  It may still sound far-fetched, but worth considering.
>                               ---------Ken Kinman
> Weblink to Briggs 2015 artucke:    https://royalsocietypublishing.org/doi/10.1098/rstb.2014.0313
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--
he/him
PhD Student
Zoomorphology
Ludwig-Maximilians-Universität München
Munich, Germany

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