Riccardiothallus devonicus gen. et sp. nov., the earliest simple thalloid liverwort from the Lower Devonian of Yunnan, China

Guo, Cai-Qing, Edwards, Dianne ORCID: https://orcid.org/0000-0002-9786-4395, Wu, Peng-Cheng, Duckett, Jeffrey G., Hueber, Francis M. and Li, Cheng-Sen 2012. Riccardiothallus devonicus gen. et sp. nov., the earliest simple thalloid liverwort from the Lower Devonian of Yunnan, China. Review of Palaeobotany and Palynology 176-77 , pp. 35-40. 10.1016/j.revpalbo.2012.03.012

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Abstract

This paper describes a fossil liverwort in the Posongchong Formation, Lower Devonian (Pragian), Yunnan, China preserved as a partially permineralized compression in gray arenaceous mudstone. The plant comprises a regularly-bifurcating flat ecostate multilayered thallus with entire margins. Following comparisons of this fossil with gametophytes of extant and fossil liverworts, a new genus Riccardiothallus was established in the family Aneuraceae (Jungermanniopsida). The fossil, which appears to be closely similar to several members of the extant genus Riccardia, is the earliest unequivocal megafossil evidence of a liverwort. Considering the sedimentary environment of Riccardiothallus devonicus and the habitats of many extant Riccardia species, we conclude that Riccardiothallus devonicus probably lived in a warm and humid riverine environment. The age (Pragian, 407–411 Ma) of Riccardiothallus devonicus suggests that the differentiation of Jungermanniopsida and Metzgeriidae was in the Early Devonian, significantly earlier than the assumptions derived from analyses of chloroplast DNA sequences of modern liverworts and current total evidence phylogenies (Late Devonian, 359–385 Ma; Late Carboniferous, 299–307 Ma).

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Earth and Environmental Sciences
Subjects:	G Geography. Anthropology. Recreation > GB Physical geography
Uncontrolled Keywords:	Aneuraceae; Riccardiothallus devonicus; fossil liverwort; Lower Devonian; Yunnan; China
Publisher:	Elsevier
ISSN:	0034-6667
Last Modified:	20 Oct 2022 09:33
URI:	https://orca.cardiff.ac.uk/id/eprint/32479

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