RATZEL, STEPHEN R.*, GAR W. ROTHWELL, ROYAL H. MAPES, GENE MAPES, AND LARISA A. DOGUZHAEVA. Department of Environmental and Plant Biology, Ohio University, Athens OH 45701, U.S.A.; Department of Geological Sciences; Ohio University, Athens OH 45701, U.S.A.; and Paleontological Institute, Russian Academy of Sciences, Moscow 117868, Russia. - Pityostrobus in the Lower Cretaceous of southwestern Russia.
A species of Pityostrobus (P. milleri Falder et al.)
recently was described from calcareous nodules recovered from shallow
marine sediments of Lower Cretaceous (latest Aptian: Clansenian) age
located east of the Black Sea in the Caucasus Mountains in
southwestern Russia. Nodules of this type also contain conifer
needles, filicalean frond members, wood fragments, gastropods,
bivalves, and an extremely rich assemblage of well preserved
cephalopods. Additional collecting at this locality has yielded a
second new species of this extinct ovulate cone genus assignable to
the Pinaceae. The incomplete cone measures 8 cm long and 3.4 cm wide.
The cone axis is 5 mm in diameter, with a parenchymatous pith that
displays scattered sclerids. The cylinder of wood is discontinuous
and does not show a growth ring. The tiny bract is united with the
scale except at the tip. Bract and scale traces diverge from the
stele independently, and the bract trace extends to near the tip of
the organ. Resin canal architecture is distinct, but similar to that
of Larix, Pseudotsuga and Picea. Ovules display
a distinctly undulating surface of the integument on the side that
faces the ovuliferous scale. This new species adds further to our
knowledge of the explosive diversification of Pinaceae during Early
Cretaceous time.
Key words: Lower Cretaceous, Pinaceae, Pityostrobus, Russia, seed cone