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Ultrastructure of enigmatic phytoclasts (banded tubes) from the Silurian-Lower Devonian; evidence for affinities and role in early terrestrial ecosystems

Wilson A. Taylor and Charles H. Wellman
Ultrastructure of enigmatic phytoclasts (banded tubes) from the Silurian-Lower Devonian; evidence for affinities and role in early terrestrial ecosystems
Palaios (March 2009) 24 (3): 167-180

Abstract

Microfossil tubes with internal thickenings, so-called banded tubes, are a conspicuous but enigmatic element of terrestrial palynomorph assemblages of Silurian to Early Devonian age. Their biological affinities and functions are controversial. Most researchers favor derivation from nematophytes, themselves an enigmatic group of organisms that are often considered to represent early terrestrial fungi-like organisms. Here we present the first transmission electron microscope (TEM) ultrastructural analysis of these banded tubes and show that their walls are homogeneous and lack preserved ultrastructure. Gross wall structure is extremely variable with respect to the nature of the thickenings, suggesting that the tubes were derived from a variety of sources or were highly variable within the source organism. Ultrastructurally, the tubes differ markedly from contemporaneous vascular plant tracheids. We discuss the affinities of the tubes based on the new ultrastructural and structural information, and we conclude that they most likely derive from nematophytes, heterotrophic organisms with fungal-like ecology, where they served as hyphal-like structures, anchoring the organism and transporting nutrients.


ISSN: 0883-1351
Serial Title: Palaios
Serial Volume: 24
Serial Issue: 3
Title: Ultrastructure of enigmatic phytoclasts (banded tubes) from the Silurian-Lower Devonian; evidence for affinities and role in early terrestrial ecosystems
Affiliation: University of Wisconsin-Eau Claire, Department of Biology, Eau Claire, WI, United States
Pages: 167-180
Published: 200903
Text Language: English
Publisher: Society for Sedimentary Geology, Tulsa, OK, United States
References: 71
Accession Number: 2009-032352
Categories: General paleontology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables
N47°49'60" - N49°15'00", W68°00'00" - W64°15'00"
Secondary Affiliation: University of Sheffield, GBR, United Kingdom
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 200918
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