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An Ordovician nectocaridid hints at an endocochleate origin of Cephalopoda

Smith, M.R.

An Ordovician nectocaridid hints at an endocochleate origin of Cephalopoda Thumbnail


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Abstract

Nectocaridids are soft-bodied Cambrian organisms that have been controversially interpreted as primitive cephalopods, contradicting the long-held belief that these molluscs evolved from a shell-bearing ancestor. Here I document a new nectocaridid from the Whetstone Gulf formation, extending the group’s range into the Late Ordovician. Nectocotis rusmithi n. gen, n. sp. possesses a robust internal element that resembles a non-mineralized phragmocone or gladius. Nectocotis can be accommodated in the cephalopod total group if (1) cephalopods inherited a non-mineralized shell field from the ancestral mollusc; (2) the earliest cephalopods bore internal shells. This evolutionary scenario would overturn the traditional ectocochleate, Nautilus-like reconstruction, and indicate a trend towards increased metabolic efficiency through the course of Cambrian–Ordovician evolution.

Citation

Smith, M. (2020). An Ordovician nectocaridid hints at an endocochleate origin of Cephalopoda. Journal of Paleontology, 94(1), 64-69. https://doi.org/10.1017/jpa.2019.57

Journal Article Type Article
Acceptance Date Jun 14, 2019
Online Publication Date Aug 15, 2019
Publication Date Jan 31, 2020
Deposit Date Jun 17, 2019
Publicly Available Date Feb 15, 2020
Journal Journal of Paleontology
Print ISSN 0022-3360
Electronic ISSN 1937-2337
Publisher Cambridge University Press
Peer Reviewed Peer Reviewed
Volume 94
Issue 1
Pages 64-69
DOI https://doi.org/10.1017/jpa.2019.57

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Accepted Journal Article (1.1 Mb)
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Publisher Licence URL
http://creativecommons.org/licenses/by-nc-nd/4.0/

Copyright Statement
This article has been published in a revised form in Journal of Paleontology 10.1017/jpa.2019.57. This version is published under a Creative Commons CC-BY-NC-ND. No commercial re-distribution or re-use allowed. Derivative works cannot be distributed. © 2019 The Paleontological Society.




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