Reconstructing a complex early Neoproterozoic eukaryote, Wynniatt Formation, Victoria Island, arctic Canada

Butterfield, N. J. (2005) Reconstructing a complex early Neoproterozoic eukaryote, Wynniatt Formation, Victoria Island, arctic Canada. Lethaia, 38 (2). pp. 155-169. DOI

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Flanged filamentous microfossils from two geographically separated assemblages in the early Neoproterozoic Wynniatt Formation, arctic Canada, co-occur with flanged Clavitrichoides -type filaments, flanged Osculosphaera-type vesicles and wrinkled, bi-layered vesicles assigned to a new acritarch form-taxon Plicatosphaeridium impostor n. gen., n. sp. Marked similarities in morphological and microstructural detail identify most, if not all, of these forms as components of a single, relatively complex, multicellular eukaryote, Cheilofilum hysteriopsis n. gen., n. sp. The filamentous, occasionally branched thallus was composed of large cylindrical cells, and extended via rupture of cell termini. Filaments originated from Clavitrichoides -type or Osculosphaera -type vesicles via a similar process of rupture, flange formation and apical extension. Presence of a distinctively mottled wall texture supports the ontogenetic relationship of Wynniatt Cheilofilum, 'Clavitrichoides' and 'Osculosphaera,' and provides circumstantial evidence for including a Plicatosphaeridium phase. Despite superficial similarities, Cheilofilum cannot be interpreted as a filamentous cyanobacterium, strobilating scyphozoan or polychaete worm tube. The distinctive cytokinesis of the filamentous component has close analogues among the annellophores and/or phialides (conidiophores) of various hyphomycetous fungi, though its large size and absence of an associated mycelium argue against its placement within the Fungi. Unambiguous fungal synapomorphies are expressed in co-occurring Tappania, however, and both Cheilofilum and Tappania include a closely comparable Clavitrichoides -type phase in their life cycle.

Item Type: Article
Uncontrolled Keywords: 2005 AREP IA46 2005 P IA48
Subjects: 04 - Palaeobiology
Divisions: 04 - Palaeobiology
Journal or Publication Title: Lethaia
Volume: 38
Page Range: pp. 155-169
Identification Number:
Depositing User: Sarah Humbert
Date Deposited: 25 Jul 2011 10:17
Last Modified: 23 Jul 2013 09:58

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