Subject: Re: [permaculture] Long Before Trees Overtook the Land, Earth Was Covered by Giant Mushrooms | Smart News
Date: Thu, 7 Nov 2013 07:55:43 -0800
The thinking is that these "fungi" lived off of bryophytes and other early
land organisms: "a biologically heterogeneous mosaic of primary producers."
Big things can be made by consuming little things (look at baleen whales).
They needn't have consumed trees, altho I had the same response that you did.
Taxonomically, they do seem to be fungi. Here's an abstract of the original
article from the journal "Geology." http://geology.gsapubs.org/content/35/5/399.abstract
Devonian landscape heterogeneity recorded by a giant fungus
C. Kevin Boyce1, Carol L. Hotton2, Marilyn L. Fogel3, George D. Cody3,Robert
M. Hazen3, Andrew H. Knoll4 and Francis M. Hueber5
+Author Affiliations
1Department of the Geophysical Sciences, University of Chicago, 5734 South
Ellis Ave., Chicago, Illinois 60637, USA
2Department of Paleobiology, NHB MRC 121, National Museum of Natural History,
Washington, D.C. 20560, USA
3Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad
Branch Road NW, Washington, D.C. 20015, USA
4Department of Organismic and Evolutionary Biology, Harvard University, 26
Oxford Street, Cambridge, Massachusetts 02138, USA
5Department of Paleobiology, NHB MRC 121, National Museum of Natural History,
Washington, D.C. 20560, USA
Abstract
The enigmatic Paleozoic fossil Prototaxites Dawson 1859 consists of tree-like
trunks as long as 8 m constructed of interwoven tubes <50 mm in
diameter.Prototaxites specimens from five localities differ from
contemporaneous vascular plants by exhibiting a carbon isotopic range, within
and between localities, of as much as 13‰ δ13C. Pyrolysis–gas
chromatography–mass spectrometry highlights compositional differences between
Prototaxites and co-occurring plant fossils and supports interpretation of
isotopic distinctions as biological rather than diagenetic in origin. Such a
large isotopic range is difficult to reconcile with an autotrophic
metabolism, suggesting instead that, consistent with anatomy-based
interpretation as a fungus, Prototaxites was a heterotroph that lived on
isotopically heterogeneous substrates. Light isotopic values of
Prototaxitesapproximate those of vascular plants from the same localities; in
contrast, heavy extremes seen in the Lower Devonian appear to reflect
consumption of primary producers with carbon-concentrating mechanisms, such
as cryptobiotic soil crusts, or possibly bryophytes. Prototaxites
biogeochemistry thus suggests that a biologically heterogeneous mosaic of
primary producers characterized land surfaces well into the vascular plant
era.