SMITH, SELENA Y.* AND RUTH A. STOCKEY. Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9. - A permineralized Pityostrobus cone (Pinaceae) from the Cretaceous of British Columbia.
One cylindrical abraded cone specimen, 2.8 cm in diameter and at least
3.0 cm long, has been found in a calcareous concretion from the
Cretaceous Oyster Bay Formation (Late Campanian) of Vancouver Island,
British Columbia. The cone was sectioned and peeled using the
cellulose acetate peel technique. Sclerenchymatous pith is surrounded
by a ring of separate secondary xylem bundles that lack resin canals.
Numerous dilating resin canals occur in the inner parenchymatous
cortex. The thick, sclerenchymatous outer cortical zone is covered in
a dense ramentum of trichomes. Trichomes are also found on ovuliferous
scale and bract bases. Vascular traces to ovuliferous scales and
bracts arise independently. The bract is keeled with a terete trace
and two lateral resin canals. Ovuliferous scales are sclerotic with
resin canals adaxial, abaxial, and in between the vascular strands. A
prominent interseminal ridge occurs between the two winged seeds of
each scale. Seeds have a ridged sclerotesta; and nucellus,
megagametophyte, and embryos with eight cotyledons are preserved. Cone
structure most closely resembles the fossil pinaceous genus
Pityostrobus. The unique features of this cone distinguish it
from the known species of Pityostrobus and extant Pinaceae and
emphasize the rapid evolution and diversification of the family
Pinaceae that occured during the Cretaceous.
Key words: conifers, Cretaceous, Pinaceae, Pityostrobus