Please use this identifier to cite or link to this item: http://hdl.handle.net/2381/42673
Title: Naked chancelloriids from the lower Cambrian of China show evidence for sponge-type growth
Authors: Cong, Pei-Yun
Harvey, Thomas H. P.
Williams, Mark
Siveter, David J.
Siveter, Derek J.
Gabbott, Sarah E.
Li, Yu-Jing
Wei, Fan
Hou, Xian-Guang
First Published: 20-Jun-2018
Publisher: The Royal Society
Citation: Proceedings of the Royal Society B, 2018, 285(1881): 20180296
Abstract: Chancelloriids are an extinct group of spiny Cambrian animals of uncertain phylogenetic position. Despite their sponge-like body plan, their spines are unlike modern sponge spicules, but share several features with the sclerites of certain Cambrian bilaterians, notably halkieriids. However, a proposed homology of these ‘coelosclerites' implies complex transitions in body plan evolution. A new species of chancelloriid, Allonnia nuda, from the lower Cambrian (Stage 3) Chengjiang Lagerstätte is distinguished by its large size and sparse spination, with modified apical sclerites surrounding an opening into the body cavity. The sclerite arrangement in A. nuda and certain other chancelloriids indicates that growth involved sclerite addition in a subapical region, thus maintaining distinct zones of body sclerites and apical sclerites. This pattern is not seen in halkieriids, but occurs in some modern calcarean sponges. With scleritome assembly consistent with a sponge affinity, and in the absence of cnidarian- or bilaterian-grade features, it is possible to interpret chancelloriids as sponges with an unusually robust outer epithelium, strict developmental control of body axis formation, distinctive spicule-like structures and, by implication, minute ostia too small to be resolved in fossils. In this light, chancelloriids may contribute to the emerging picture of high disparity among early sponges.
DOI Link: 10.1098/rspb.2018.0296
ISSN: 0962-8452
eISSN: 1471-2954
Links: http://rspb.royalsocietypublishing.org/content/285/1881/20180296
http://hdl.handle.net/2381/42673
Version: Post-print
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © 2018, The Royal Society. Deposited with reference to the publisher’s open access archiving policy. (http://www.rioxx.net/licenses/all-rights-reserved)
Description: Electronic supplementary material is available online at https://dx.doi.org/10.6084/m9.figshare.c.4127369
Appears in Collections:Published Articles, Dept. of Geology

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