| Abstract Detail
Paleobotany Jud, Nathan [1], Bradley, Kiara [1], Zahnd, Benjamin [1], Rothwell, Gar [2], Stockey, Ruth [3], Beard, Graham [4]. A second species of liana from the Upper Cretaceous (Campanian) of Hornby Island, British Columbia, Canada. Fossil woods are preserved in calcareous concretions from Cretaceous (Campanian) sediments of Collishaw Point, Hornby Island, British Columbia. Among the fossils is a segment of a woody dicot stem 4.5 cm in diameter. The stem was sectioned using the cellulose acetate peel technique. The center of the axis is incompletely preserved; portions of the pith and wood appear to have been removed by insect feeding prior to preservation leaving a sediment filled gallery. The wood is semi-ring-porous, with five or six growth increments marked by zones of narrower vessels in between zones of wider vessels. Vessels are solitary and in radial multiples (solitary: 28%, in pairs: 25%, threes: 18%, fours: 10%, more than four: 17%). Vessel diameter increases abruptly to c. 100 µm within approximately 1 mm of the margin of the pith. Mean tangential diameter of the vessels near the periphery is 128 µm (sd: 26.5; max: 255 µm; n=25). Vessel frequency is 21.5 mm2. Perforation plates are simple and oblique to nearly perpendicular. In longitudinal sections, mean vessel element length is 367 µm (range: 164–590 µm, SD: 119). Lateral walls of the vessel elements bear medium to large (8–14 µm), crowded, elliptical, alternate pits. Vessel-ray parenchyma pits are circular with reduced borders. Tyloses are locally common in the vessels. Axial parenchyma is diffuse and scanty paratracheal, not storied. Fibers thin to thick-walled and not storied. Rays are dimorphic and heterocellular. Narrower rays typically 1–6 cells wide and < 1 mm tall, whereas the wider rays are >10 cells wide and >1 mm tall. The pith tissue consists of columns of parenchyma cells ranging from 42–88 µm (mean = 54, n = 25) in diameter and 29–60 µm long (mean = 42, n = 25) near the center and 18–34 µm (mean = 22, n = 25) in diameter and 19–157 µm long (mean = 70, n = 25) near the periphery. The bark is 4–5 mm thick. Phloem rays intrude from the bark into the larger xylem rays. Wide vessels combined with wide rays and thick inner bark relative to the diameter of the woody cylinder, as in this specimen, are characteristics of liana stem anatomy. This is the second liana stem to be identified from the Collishaw Point assemblage. Liana species richness and abundance is associated with diverse, structurally complex forests, so the discovery of a second species among the numerous other dicots woods from the same locality suggests high angiosperm diversity in a Late Cretaceous forest.
1 - William Jewell College, Biology, 500 College Hill, Liberty, MO, 64068, USA
2 - Oregon State University, Department Of Botany And Plant Pathology, 2082 Cordley Hall, Corvallis, OR, 97331, United States
3 - Department Of Botany And Plant Pathology, 4575 Research Way, Research Lab Building, Corvallis, OR, 97333, United States
4 - Vancouver Island Paleontology Museum, Qualicum Beach, BC, V9K 1K7, Canada
Keywords:
fossil.
Presentation Type: Poster
Number: PPB004
Abstract ID:949
Candidate for Awards:None |
