Morphological disparity in extant and extinct sepiid phragmocones: morphological adaptions for phragmocone strength compared to those related to cameral liquid emptying hypotheses

Abstract The phragmocone-bearing coleoid cephalopods Sepia, Sepiella, Metasepia and Hemisepius (sepiids) are the most diverse of all extant chambered cephalopods and show the highest disparity. As such, they have a great potential to serve as model organisms to better understand the paleobiology not...

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Main Authors: Peter D. Ward, Job Lukas Veloso, Christian Klug
Format: Article
Language:English
Published: SpringerOpen 2022-05-01
Series:Swiss Journal of Palaeontology
Subjects:
Online Access:https://doi.org/10.1186/s13358-022-00248-0
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author Peter D. Ward
Job Lukas Veloso
Christian Klug
author_facet Peter D. Ward
Job Lukas Veloso
Christian Klug
author_sort Peter D. Ward
collection DOAJ
description Abstract The phragmocone-bearing coleoid cephalopods Sepia, Sepiella, Metasepia and Hemisepius (sepiids) are the most diverse of all extant chambered cephalopods and show the highest disparity. As such, they have a great potential to serve as model organisms to better understand the paleobiology not only of extinct coleoids, but of extinct nautiloids and ammonoids as well. Here, we present new measurements from the phragmocones of Sepia and Sepiella and relate these to known maximum depths. While these latter data remain few for some species, in aggregate they provide progress allowing this work. In so doing, we expand upon the great legacy of Sigurd von Boletzky. We show that deep water-inhabiting sepiids have phragmocones with a higher number of septa per length, a smaller area covered by the last chamber in relation to the volume of all previous phragmocone chambers, are smaller in size (length and volume), and bear dorsal shields that have strengthening central rib(s) compared to most species from shallower water; the very small endemic species of South Africa may be an exception. We show that the various subgenera defined by Khromov (1987) are not monophyletic clades but morphological groupings explicitly related to depth, partially evolved convergently. We conclude with analyses of Australian sepiid assemblages and show that these are depth related in ways analogous to ammonite and/or nautiloid assemblages of the past that are later commingled through post-mortal drift.
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spelling doaj.art-ef4105b9286a4578918d568ca08cb0792022-12-22T02:54:41ZengSpringerOpenSwiss Journal of Palaeontology1664-23761664-23842022-05-01141111810.1186/s13358-022-00248-0Morphological disparity in extant and extinct sepiid phragmocones: morphological adaptions for phragmocone strength compared to those related to cameral liquid emptying hypothesesPeter D. Ward0Job Lukas Veloso1Christian Klug2Department of Biology, University of WashingtonDepartment of Biology, University of WashingtonPaläontologisches Institut und Museum, Universität ZürichAbstract The phragmocone-bearing coleoid cephalopods Sepia, Sepiella, Metasepia and Hemisepius (sepiids) are the most diverse of all extant chambered cephalopods and show the highest disparity. As such, they have a great potential to serve as model organisms to better understand the paleobiology not only of extinct coleoids, but of extinct nautiloids and ammonoids as well. Here, we present new measurements from the phragmocones of Sepia and Sepiella and relate these to known maximum depths. While these latter data remain few for some species, in aggregate they provide progress allowing this work. In so doing, we expand upon the great legacy of Sigurd von Boletzky. We show that deep water-inhabiting sepiids have phragmocones with a higher number of septa per length, a smaller area covered by the last chamber in relation to the volume of all previous phragmocone chambers, are smaller in size (length and volume), and bear dorsal shields that have strengthening central rib(s) compared to most species from shallower water; the very small endemic species of South Africa may be an exception. We show that the various subgenera defined by Khromov (1987) are not monophyletic clades but morphological groupings explicitly related to depth, partially evolved convergently. We conclude with analyses of Australian sepiid assemblages and show that these are depth related in ways analogous to ammonite and/or nautiloid assemblages of the past that are later commingled through post-mortal drift.https://doi.org/10.1186/s13358-022-00248-0ColeoideaCephalopodaDevelopmentEcologyEvolutionSystematics
spellingShingle Peter D. Ward
Job Lukas Veloso
Christian Klug
Morphological disparity in extant and extinct sepiid phragmocones: morphological adaptions for phragmocone strength compared to those related to cameral liquid emptying hypotheses
Swiss Journal of Palaeontology
Coleoidea
Cephalopoda
Development
Ecology
Evolution
Systematics
title Morphological disparity in extant and extinct sepiid phragmocones: morphological adaptions for phragmocone strength compared to those related to cameral liquid emptying hypotheses
title_full Morphological disparity in extant and extinct sepiid phragmocones: morphological adaptions for phragmocone strength compared to those related to cameral liquid emptying hypotheses
title_fullStr Morphological disparity in extant and extinct sepiid phragmocones: morphological adaptions for phragmocone strength compared to those related to cameral liquid emptying hypotheses
title_full_unstemmed Morphological disparity in extant and extinct sepiid phragmocones: morphological adaptions for phragmocone strength compared to those related to cameral liquid emptying hypotheses
title_short Morphological disparity in extant and extinct sepiid phragmocones: morphological adaptions for phragmocone strength compared to those related to cameral liquid emptying hypotheses
title_sort morphological disparity in extant and extinct sepiid phragmocones morphological adaptions for phragmocone strength compared to those related to cameral liquid emptying hypotheses
topic Coleoidea
Cephalopoda
Development
Ecology
Evolution
Systematics
url https://doi.org/10.1186/s13358-022-00248-0
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