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Pallavicinites devonicus (Huber) Schuster
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Pallavicinites devonicus (Huber) Schuster, from the upper Devonian of New York: the oldest known bryophyte.

The oldest unequivocal fossil bryophyte was recovered from lowermost upper Devonian (Famenian) rocks from New York. The specimens were part of a mixed plant assemblage of compression fossils including, Psilophyton princeps Dawson, Schizopodium Harris, Cladoxylon Unger, Pseudosporochnus Potonie and Bernard, and Eospermatopteris (Dawson) Goldring among other taxa. The bryophyte specimens were first analyzed by R.M. Schuster in 1960, who then passed them on to Hueber (1961) who described them as Hepaticites devonicus. Schuster (1966) re-named this liverwort Pallavicinites devonicus because of the specimens similarity to the extant thallos liverwort Pallavicinia : in particular, the presence of few celled marginal teeth on the lamella of the thallus.

Pallavicinites, as reconstructed from material recovered by the bulk HF maceration technique, is pleuricarpose with a rhizome giving rise to an irregularly dichotomously branched, probably erect to sub-erect thallus. The rhizome is elliptical to terete in cross section and is 0.58 to 1.7 mm in diameter with numerous non-sepate rhizoids produced on the surface. The cells of the rhizome are parenchymatous and elongate. Rhizoids average 21mm in diameter with an unknown maximum length due to breakage. The thallus is costate, with a unistratose lamella. The costa is two to several cells thick. At the center of the costa these cells are 14 to 26mm in diameter and of unknown, but considerable length. At the boundary between costa and lamella the cells of the costa are approximately 140 mm long. Cells of the lamella are leptodermous, polygonal, and 46.8 to 73.2 mm in diameter. No rhizoids are observed on the thallus. The margin of the lamella is unlobed, but armed with curved teeth spaced approximately 0.18mm apart. The teeth are apically oriented and formed of one to several cells. Reproductive structures are unknown.

References:
Hueber, F.M. 1961. Hepaticites devonicus : a new fossil liverwort from the Devonian of New York. Annals of the Missouri Botanical Garden, 48(2): 125-132.

Karssilov, V.A., and Schuster, R.M. 1984. Paleozoic and Mesozoic fossils. (In): Schuster, R.M. (Ed.), New Manual of Bryology , The Hattori Botanical Garden, Vol. 2, Ch. 19:1172-1193.

Malcolm, B, and Malcolm, N. 2000. Mosses and other Bryophytes: an Illustrated Glossary . Micro-Optic Press, New Zealand, 220p.

Oostendorp, C. 1987. The bryophytes of the Paleozoic and Mesozoic. Bryophytorium Bibliotheca , Band 34, p112.

Schuster, R.M., 1966. The Hepaticae and Anthocerotae of North America, east of the Hundredth Meridian. Vol.1, Columbia University Press.

Written by Michael T. Dunn
May 2001

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