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Stable carbon isotopes and the metabolism of the terrestrial Devonian organism Spongiophyton
Author(s) -
FLETCHER BENJAMIN J.,
BEERLING DAVID J.,
CHALONER WILLIAM. G.
Publication year - 2004
Publication title -
geobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.859
H-Index - 72
eISSN - 1472-4669
pISSN - 1472-4677
DOI - 10.1111/j.1472-4677.2004.00026.x
Subject(s) - lichen , devonian , algae , isotopes of carbon , extant taxon , stable isotope ratio , carbon fibers , isotopic signature , biology , isotope , paleontology , ecology , botany , geology , evolutionary biology , total organic carbon , physics , materials science , quantum mechanics , composite number , composite material
Devonian fossils of Spongiophyton have been identified as a terrestrial evolutionary intermediate between algae and vascular land plants on the basis of their dichotomously branched, tubular morphology, thick cuticles, and the scattered distribution of surface pores. Our understanding of their physiology is, however, severely limited, but may be increased through the use of stable carbon isotope measurements. One such study led to the hypothesis that Spongiophyton carried a carbon isotope (δ 13 C) signature characteristic of lichens (Jahren et al ., 2003 Geology 31 , 99–102). Here, we outline three difficulties with accepting this idea and report independent isotopic measurements of Spongiophyton fossils from Canada and Ghana. Our results show that the isotopic discrimination of analogous tissues of Spongiophyton , extant lichens, liverworts and mosses are statistically indistinguishable. We suggest therefore that claims to have definitively identified lichen metabolism are premature, and cannot be sustained.