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Filamentous eukaryotic algae with a possible cladophoralean affinity from the Middle Ordovician Winneshiek Lagerstätte in Iowa, USA

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posted on 03.11.2017, 12:48 by Hendrik Nowak, Thomas H.P. Harvey, Huaibao P. Liu, Robert M. McKay, Pierre A. Zippi, Donald H. Campbell, Thomas Servais
Previous studies on the Darriwilian (Middle Ordovician) Konservat-Lagerstätte of the Winneshiek Shale in Iowa (USA) have reported various animal and trace fossils. A search for ‘‘small carbonaceous fossils’’ (SCFs) in palynological samples from the Winneshiek Shale has now led to the discovery of several different kinds of organic-walled microfossils. Here we report on a particular group of filamentous microfossils that occur abundantly throughout the exposed and subsurface successions of the Winneshiek Shale. The fossils are characterised by large, elongated cells (220–600 mm in length, 60– 240 mm in diameter) with thin and delicate walls and occasional branching. The cells often contain dark internal bodies, most likely condensed protoplasmic remains. Together, these features identify these fossils as eukaryotic rather than cyanobacterial in origin. More specifically, the cell size, cross-walls and branching pattern are shared with forms of benthic ulvophycean green algae, a group with a long but sporadic fossil record that is otherwise restricted to Proterozoic Lagersta¨tten. The new specimens therefore expand the known diversity of local primary producers in the palaeoenvironment of the Winneshiek Shale, and suggest that the apparent dearth of delicate filamentous green algae in the Phanerozoic record may be, in part, an artefact of low preservation potential combined with destructive processing techniques.

History

Citation

Geobios, 2017, 50, pp. 303–309

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Geology

Version

AM (Accepted Manuscript)

Published in

Geobios

Publisher

Elsevier Masson

issn

0016-6995

Acceptance date

18/06/2017

Copyright date

2017

Available date

23/06/2018

Publisher version

https://ac.els-cdn.com/S0016699517300037/1-s2.0-S0016699517300037-main.pdf?_tid=c44ec1e0-c091-11e7-a367-00000aab0f26&acdnat=1509711975_737304ed20e231ca520c291c85e507c7

Notes

The file associated with this record is under embargo until 12 months after publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.

Language

en