Archaeopteris from the Upper Famennian of Belgium: heterospory, nomenclature, and palaeobiogeography

Abstract

New fertile specimens of Archaeopteris roemeriana from Upper (but not uppermost) Famennian strata of Belgium have been studied. Crowded sporangia are borne on non-laminate, three times bifurcate fertile leaves helically arranged around the fertile ultimate axes. Vegetative leaves occur both proximal and distal to the fertile leaves. Heterospory is demonstrated with miospores belonging to the Geminospora-Aneurospora complex and macrospores most probably to Contagisporites genus. The established morphological traits allow us to substantiate a synonymy between A. roemeriana and A. halliana. The apparent dominance of A. halliana on the eastern side of the Acadian mountains during Late Famennian times is discussed.

Anatomical reinvestigation of Archaeopteris macilenta from the Upper Devonian (Frasnian) of South China

“…halliana is presently unknown. Kräusel & Weyland (1941) and Fairon‐Demaret et al (2001) proposed that these two species are synonymous. In addition, A .…”

“…roemeriana ) are characterized by laminated and non‐laminated fertile leaves, respectively. Fairon‐Demaret et al (2001) suggested that their different leaf shapes mainly correlate with distinct biotopes, that is, non‐laminated fertile leaves of A . roemeriana may be more efficient for wind dispersal of spores and for good control of water loss by transpiration; this reproductive organ may help better cope with dry and stressful periods of a lower water table in the Late Famennian.…”

“…The axes of A. macilenta bear abundant vegetative and/or fertile leaves, which are preserved as impressions, compressions, and limonitic permineralizations in white-gray silty mudstone. New York, West Virginia (USA); Bear Island (Norway); Moresnet, Booze-Trembleur, Evieux, Durnal (Belgium); Altai-Sayan (Russia); Anhui, Guangdong (China) Radchenko, 1962;Carluccio et al, 1966;Phillips et al, 1972;Li et al, 1984;Cai et al, 1987;Kenrick & Fairon-Demaret, 1991;Fairon-Demaret et al, 2001;Osborne et al, 2004;Gutak et al, 2011 A. hibernica Kiltorcan (Ireland); New York (USA); Southeastern Mountainous Altay (Russia) Carluccio et al, 1966;Dawson, 1871;Gutak et al, 2011 A. obtusa New York (USA); Ellesmere Island (Canada) Carluccio et al, 1966;Gensel & Andrews, 1984 A. macilenta (A. fimbriata)…”

“…Archaeopteris roemeriana from Europe is very similar to A. halliana from North America in morphological characters, for example, spiral arrangement of leaves, entire and slightly uneven vegetative leaves, and non-laminated fertile leaves (Arnold, 1939;Stockmans, 1948;Phillips et al, 1972;Kenrick & Fairon-Demaret, 1991), despite that the anatomy of A. halliana is presently unknown. Kräusel & Weyland (1941) and Fairon-Demaret et al (2001) proposed that these two species are synonymous. In addition, A. macilenta and A. fimbriata are gathered under a single species and the former specific epithet has priority (Carluccio et al, 1966).…”

“…However, A. macilenta and A. halliana (A. roemeriana) are characterized by laminated and non-laminated fertile leaves, respectively. Fairon-Demaret et al (2001) suggested that their different leaf shapes mainly correlate with distinct biotopes, that is, non-laminated fertile leaves of A. roemeriana may be more efficient for wind dispersal of spores and for good control of water loss by transpiration; this reproductive organ may help better cope with dry and stressful periods of a lower water table in the Late Famennian. It should be noted that A. halliana (A. roemeriana) and A. macilenta possess similarly sized (less than 2 cm in length) vegetative leaves, which have entire-slightly uneven and deeply dissected margins, respectively (Guo & Wang, 2009, table 2).…”