MAMAY, SERGIUS H.*, DAN S. CHANEY, AND WILLIAM A. DIMICHELE. Department of Paleobiology, NMNH Smithsonian Institution, Washington, DC 20560. - A Mesozoic-type flora from the Lower Permian of Texas.
A fossil plant assemblage from the basal Blaine Formation (Leonardian,
Lower Permian) of Knox County, Texas, is one of the youngest Paleozoic
floras known in North America. It is dominated by coniferous parts
(e.g. Ullmannia- and Podozamites-like shoots and a few
undetermined cones), abundant detached seeds -- some bearing paired
wing-like appendages -- and many isolated Voltzia- or
Svedenborgia-like cone scale complexes. "Typical"
Paleozoic pteridophylls (callipterids, gigantopterids, etc.) are
strangely absent; the only plants reminiscent of Paleozoic floras are
Taeniopteris, samaropsid seeds, and the enigmatic
Wattia. Primary interest lies in 30-odd specimens of
Dioonitocarpidium (Lilienstern, 1928), a cycadean
megasporophyll previously known only from Keuper (Upper Triassic) beds
of Bavaria. These are long, pinnatifid appendages with a short, broad
stalk and a narrow lamina, which is deeply incised into narrow basal
segments that progressively shorten and usually merge into an entire
distal margin and apiculate tip. The largest specimens are about 7.0
cm long and 1.5 cm wide. Two seeds are attached to separate sporophyll
stalks, and most sporophylls retain a dense indument of short hairs.
Excepting minor quantitative differences, the Texas sporophylls are
morphologically identical with Krausel's (1943) illustrations of
Dioonitocarpidium keuperianum (Krasser) Krausel. Thus they
contribute to cycadalean history and enhance the
"precocious" overall Triassic flavor of this Early Permian
flora.
Key words: conifer, cycad, Paleozoic, Permian