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3D-Analysis of a non-planispiral ammonoid from the Hunsrück Slate: natural or pathological variation?

We herein examine the only known non-planispirally coiled early Devonian ammonoid, the holotype specimen of Ivoites opitzi, to investigate if the host was encrusted in vivo and if these sclerobionts were responsible for the trochospiral coiling observed in this unique specimen. To test if the presen...

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Autores principales: Stilkerich, Julia, Smrecak, Trisha A., De Baets, Kenneth
Formato: Online Artículo Texto
Lenguaje:English
Publicado: PeerJ Inc. 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5494166/
https://www.ncbi.nlm.nih.gov/pubmed/28674668
http://dx.doi.org/10.7717/peerj.3526
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author Stilkerich, Julia
Smrecak, Trisha A.
De Baets, Kenneth
author_facet Stilkerich, Julia
Smrecak, Trisha A.
De Baets, Kenneth
author_sort Stilkerich, Julia
collection PubMed
description We herein examine the only known non-planispirally coiled early Devonian ammonoid, the holotype specimen of Ivoites opitzi, to investigate if the host was encrusted in vivo and if these sclerobionts were responsible for the trochospiral coiling observed in this unique specimen. To test if the presence of runner-like sclerobionts infested the historically collected specimen of Ivoites opitzi during its life, we used microCT to produce a three-dimensional model of the surface of the specimen. Our results indicate that sclerobionts grew across the outer rim (venter) on both sides of the ammonoid conch at exactly the location where the deviation from the planispiral was recognized, and where subsequent ammonoid growth would likely preclude encrustation. This indicates in vivo encrustation of the I. opitzi specimen, and represents the earliest documentation of the phenomenon. Further, this suggests that non-planispiral coiling in I. opitzi was likely pathologically induced and does not represent natural morphological variation in the species. Despite the observed anomalies in coiling, the specimen reached adulthood and retains important identifying morphological features, suggesting the ammonoid was minimally impacted by encrustation in life. As such, appointing a new type specimen—as suggested by some authors—for the species is not necessary. In addition, we identify the sclerobionts responsible for modifying the coiling of this specimen as hederelloids, a peculiar group of sclerobionts likely related to phoronids. Hederelloids in the Devonian are commonly found encrusting on fossils collected in moderately deep environments within the photic zone and are rarely documented in dysphotic and aphotic samples. This indicates that when the ammonoid was encrusted it lived within the euphotic zone and supports the latest interpretations of the Hunsrück Slate depositional environment in the Bundenbach-Gemünden area.
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spelling pubmed-54941662017-07-03 3D-Analysis of a non-planispiral ammonoid from the Hunsrück Slate: natural or pathological variation? Stilkerich, Julia Smrecak, Trisha A. De Baets, Kenneth PeerJ Ecology We herein examine the only known non-planispirally coiled early Devonian ammonoid, the holotype specimen of Ivoites opitzi, to investigate if the host was encrusted in vivo and if these sclerobionts were responsible for the trochospiral coiling observed in this unique specimen. To test if the presence of runner-like sclerobionts infested the historically collected specimen of Ivoites opitzi during its life, we used microCT to produce a three-dimensional model of the surface of the specimen. Our results indicate that sclerobionts grew across the outer rim (venter) on both sides of the ammonoid conch at exactly the location where the deviation from the planispiral was recognized, and where subsequent ammonoid growth would likely preclude encrustation. This indicates in vivo encrustation of the I. opitzi specimen, and represents the earliest documentation of the phenomenon. Further, this suggests that non-planispiral coiling in I. opitzi was likely pathologically induced and does not represent natural morphological variation in the species. Despite the observed anomalies in coiling, the specimen reached adulthood and retains important identifying morphological features, suggesting the ammonoid was minimally impacted by encrustation in life. As such, appointing a new type specimen—as suggested by some authors—for the species is not necessary. In addition, we identify the sclerobionts responsible for modifying the coiling of this specimen as hederelloids, a peculiar group of sclerobionts likely related to phoronids. Hederelloids in the Devonian are commonly found encrusting on fossils collected in moderately deep environments within the photic zone and are rarely documented in dysphotic and aphotic samples. This indicates that when the ammonoid was encrusted it lived within the euphotic zone and supports the latest interpretations of the Hunsrück Slate depositional environment in the Bundenbach-Gemünden area. PeerJ Inc. 2017-06-30 /pmc/articles/PMC5494166/ /pubmed/28674668 http://dx.doi.org/10.7717/peerj.3526 Text en ©2017 Stilkerich et al. http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited.
spellingShingle Ecology
Stilkerich, Julia
Smrecak, Trisha A.
De Baets, Kenneth
3D-Analysis of a non-planispiral ammonoid from the Hunsrück Slate: natural or pathological variation?
title 3D-Analysis of a non-planispiral ammonoid from the Hunsrück Slate: natural or pathological variation?
title_full 3D-Analysis of a non-planispiral ammonoid from the Hunsrück Slate: natural or pathological variation?
title_fullStr 3D-Analysis of a non-planispiral ammonoid from the Hunsrück Slate: natural or pathological variation?
title_full_unstemmed 3D-Analysis of a non-planispiral ammonoid from the Hunsrück Slate: natural or pathological variation?
title_short 3D-Analysis of a non-planispiral ammonoid from the Hunsrück Slate: natural or pathological variation?
title_sort 3d-analysis of a non-planispiral ammonoid from the hunsrück slate: natural or pathological variation?
topic Ecology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5494166/
https://www.ncbi.nlm.nih.gov/pubmed/28674668
http://dx.doi.org/10.7717/peerj.3526
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