Additional observations on Zosterophyllum yunnanicum Hsü from the Lower Devonian of Yunnan, China

Edwards, Dianne ORCID: https://orcid.org/0000-0002-9786-4395, Yang, Nan, Hueber, Francis M. and Li, Cheng-Sen 2015. Additional observations on Zosterophyllum yunnanicum Hsü from the Lower Devonian of Yunnan, China. Review of Palaeobotany and Palynology 221 , pp. 220-229. 10.1016/j.revpalbo.2015.03.007

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Abstract

Investigation of unfigured specimens in the original collection of Zosterophyllum yunnanicum Hsü, 1966 from the Lower Devonian (upper Pragian to basal Emsian) Xujiachong Formation, Qujing District, Yunnan, China has provided further data on both sporangial and stem anatomy. We show that the sporangia dehisced into more or less equal valves through a mechanism that involved the development of large thick-walled cells. Furthermore the coalified xylem is composed of tracheids with G-type thickenings (predominantly annular secondary thickenings with small circular to irregular perforations in the intervening wall), confirming the presence of this form of vascular element in the genus Zosterophyllum. The species diagnosis is emended. Characterisation of dehiscence mechanisms in fossil sporangia is complicated by their different modes of preservation. A brief critical survey of the marginal features in bivalved sporangia in zosterophylls and other selected species is followed by a discussion on their putative functional significance. Preservation notwithstanding, we identify clear differences in mechanisms related to the nature of the underlying cellular structure of the dehiscence feature. The distinctive groove present in many species might represent a mechanism for regulating the timing of dehiscence in response to atmospheric conditions.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Earth and Environmental Sciences
Subjects:	Q Science > QE Geology
Uncontrolled Keywords:	Zosterophyllum yunnanicum; Sporangial border; Dehiscence; Early Devonian; Yunnan Province
Additional Information:	Available online 28 March 2015 PDF uploaded in accordance with publisher's policies (http://www.sherpa.ac.uk/romeo/issn/0034-6667/) accessed 7.10.15.
Publisher:	Elsevier
ISSN:	0034-6667
Date of First Compliant Deposit:	30 March 2016
Date of Acceptance:	18 March 2015
Last Modified:	05 Dec 2024 18:15
URI:	https://orca.cardiff.ac.uk/id/eprint/77818

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