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The early Cambrian fossil embryo Pseudooides is a direct-developing cnidarian, not an early ecdysozoan

Early Cambrian Pseudooides prima has been described from embryonic and post-embryonic stages of development, exhibiting long germ-band development. There has been some debate about the pattern of segmentation, but this interpretation, as among the earliest records of ecdysozoans, has been generally...

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Autores principales: Duan, Baichuan, Dong, Xi-Ping, Porras, Luis, Vargas, Kelly, Cunningham, John A., Donoghue, Philip C. J.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Royal Society 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5745419/
https://www.ncbi.nlm.nih.gov/pubmed/29237861
http://dx.doi.org/10.1098/rspb.2017.2188
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author Duan, Baichuan
Dong, Xi-Ping
Porras, Luis
Vargas, Kelly
Cunningham, John A.
Donoghue, Philip C. J.
author_facet Duan, Baichuan
Dong, Xi-Ping
Porras, Luis
Vargas, Kelly
Cunningham, John A.
Donoghue, Philip C. J.
author_sort Duan, Baichuan
collection PubMed
description Early Cambrian Pseudooides prima has been described from embryonic and post-embryonic stages of development, exhibiting long germ-band development. There has been some debate about the pattern of segmentation, but this interpretation, as among the earliest records of ecdysozoans, has been generally accepted. Here, we show that the ‘germ band’ of P. prima embryos separates along its mid axis during development, with the transverse furrows between the ‘somites’ unfolding into the polar aperture of the ten-sided theca of Hexaconularia sichuanensis, conventionally interpreted as a scyphozoan cnidarian; co-occurring post-embryonic remains of ecdysozoans are unrelated. We recognize H. sichuanensis as a junior synonym of P. prima as a consequence of identifying these two form-taxa as distinct developmental stages of the same organism. Direct development in P. prima parallels the co-occuring olivooids Olivooides, and Quadrapyrgites and Bayesian phylogenetic analysis of a novel phenotype dataset indicates that, despite differences in their tetra-, penta- and pseudo-hexa-radial symmetry, these hexangulaconulariids comprise a clade of scyphozoan medusozoans, with Arthrochites and conulariids, that all exhibit direct development from embryo to thecate polyp. The affinity of hexangulaconulariids and olivooids to extant scyphozoan medusozoans indicates that the prevalence of tetraradial symmetry and indirect development are a vestige of a broader spectrum of body-plan symmetries and developmental modes that was manifest in their early Phanerozoic counterparts.
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spelling pubmed-57454192018-01-02 The early Cambrian fossil embryo Pseudooides is a direct-developing cnidarian, not an early ecdysozoan Duan, Baichuan Dong, Xi-Ping Porras, Luis Vargas, Kelly Cunningham, John A. Donoghue, Philip C. J. Proc Biol Sci Palaeobiology Early Cambrian Pseudooides prima has been described from embryonic and post-embryonic stages of development, exhibiting long germ-band development. There has been some debate about the pattern of segmentation, but this interpretation, as among the earliest records of ecdysozoans, has been generally accepted. Here, we show that the ‘germ band’ of P. prima embryos separates along its mid axis during development, with the transverse furrows between the ‘somites’ unfolding into the polar aperture of the ten-sided theca of Hexaconularia sichuanensis, conventionally interpreted as a scyphozoan cnidarian; co-occurring post-embryonic remains of ecdysozoans are unrelated. We recognize H. sichuanensis as a junior synonym of P. prima as a consequence of identifying these two form-taxa as distinct developmental stages of the same organism. Direct development in P. prima parallels the co-occuring olivooids Olivooides, and Quadrapyrgites and Bayesian phylogenetic analysis of a novel phenotype dataset indicates that, despite differences in their tetra-, penta- and pseudo-hexa-radial symmetry, these hexangulaconulariids comprise a clade of scyphozoan medusozoans, with Arthrochites and conulariids, that all exhibit direct development from embryo to thecate polyp. The affinity of hexangulaconulariids and olivooids to extant scyphozoan medusozoans indicates that the prevalence of tetraradial symmetry and indirect development are a vestige of a broader spectrum of body-plan symmetries and developmental modes that was manifest in their early Phanerozoic counterparts. The Royal Society 2017-12-20 2017-12-13 /pmc/articles/PMC5745419/ /pubmed/29237861 http://dx.doi.org/10.1098/rspb.2017.2188 Text en © 2017 The Authors. http://creativecommons.org/licenses/by/4.0/ Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited.
spellingShingle Palaeobiology
Duan, Baichuan
Dong, Xi-Ping
Porras, Luis
Vargas, Kelly
Cunningham, John A.
Donoghue, Philip C. J.
The early Cambrian fossil embryo Pseudooides is a direct-developing cnidarian, not an early ecdysozoan
title The early Cambrian fossil embryo Pseudooides is a direct-developing cnidarian, not an early ecdysozoan
title_full The early Cambrian fossil embryo Pseudooides is a direct-developing cnidarian, not an early ecdysozoan
title_fullStr The early Cambrian fossil embryo Pseudooides is a direct-developing cnidarian, not an early ecdysozoan
title_full_unstemmed The early Cambrian fossil embryo Pseudooides is a direct-developing cnidarian, not an early ecdysozoan
title_short The early Cambrian fossil embryo Pseudooides is a direct-developing cnidarian, not an early ecdysozoan
title_sort early cambrian fossil embryo pseudooides is a direct-developing cnidarian, not an early ecdysozoan
topic Palaeobiology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5745419/
https://www.ncbi.nlm.nih.gov/pubmed/29237861
http://dx.doi.org/10.1098/rspb.2017.2188
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