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Abstract Detail

Paleobotanical Section

Bippus, Alexander [1], Shelton, Glenn W.K. [2], Stockey, Ruth [3], Rothwell, Gar [3], Tomescu, Alexandru M.F. [1].

A polytrichaceous moss with gemmae from the Early Cretaceous of Vancouver Island (Canada).

The Early Cretaceous (Valanginian, 136 mya) Apple Bay fossil assemblage (Vancouver Island, British Columbia, Canada) comprises anatomically preserved plants representing diverse groups, including a wide variety of bryophytes. Of these, several (> 15) distinct shoots represent a morphotype recognized by its characteristic leaf anatomy consisting of prominent D-shaped costae with median guide cells. The best characterized shoot has been traced for >4 mm and displays 2/5 phyllotaxis. The stem is ca. 165 µm in diameter and poorly preserved. Leaves are long, costate, with unistratose laminae. They are appressed to the stem and 425 µm wide basally, and narrower, wide-spreading distally. The appressed part of the lamina consists of cells 12 µm in cross-sectional diameter, tapering to 8 µm cells around the edges. The D-shaped costa is 150 µm wide, 85 µm thick, and features complex organization. Adaxially, a 5-6 cell thick layer of smaller, round cells ca. 5 µm in diameter intergrades with guide cells 15-20 µm in diameter which form up to three rows. The abaxial row, comprised of the largest guide cells, forms an adaxially concave arc above 3-4 layers of stereid cells measuring 5 µm in diameter. Beneath these, a single layer of flat multi-papillate cells (12 x 23 µm) forms the abaxial epidermis. Distally, the wide-spreading portions of leaves are 335 µm wide, long-tapering, and bear 4-5 lamellae up to 3 cells tall. Leaf density increases at shoot apices, around groups of laterally flattened gemmae (100 x 50 µm wide and 100-150 µm long) borne on uniseriate stalks. The costal anatomy and photosynthetic lamellae on the adaxial side of leaves are consistent with placement of the Apple Bay moss in family Polytrichaceae. Outside the Polytrichaceae, lamellae are only known in four genera of the Pottiaceae, where they have distinctive anatomy different from the Apple Bay moss, and in Aligrimmia (Grimmiaceae), which differs from the Apple Bay moss in costal anatomy. This is the third moss species representing the third distinct moss lineage characterized to date in the Apple Bay flora. This Apple Bay moss also marks the oldest unequivocal occurrence of the Polytrichaceae and of moss gemmae in the fossil record.

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1 - Humboldt State University, Department of Biological Sciences, 1 Harpst Street, Arcata, CA, 95521, USA
2 - Humboldt State University, Biological Sciences, 120A 13th Street, Arcata, CA, 95521, USA
3 - Oregon State University, Department of Botany and Plant Pathology, 2082 Cordley Hall, Corvallis, OR, 97331, USA


Presentation Type: Oral Paper:Papers for Sections
Session: 3
Location: Melrose/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 8:45 AM
Number: 3003
Abstract ID:800
Candidate for Awards:Isabel Cookson Award,Maynard F. Moseley Award

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