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Abstract Detail

Paleobotanical Section

Shelton, Glenn W.K. [1], Stockey, Ruth [2], Tomescu, Alexandru [3].

An anatomically preserved moss with a novel combination of characters from the Early Cretaceous (Hauterivian-Valanginian) of Vancouver Island, British Columbia.

Mosses found in marine carbonate concretions at the Early Cretaceous (Hauterivian-Valanginian) Apple Bay locality on Vancouver Island represent one of the few occurrences of anatomically preserved fossil mosses worldwide. One of the several distinct morphotypes discovered at Apple Bay is represented by at least fourteen gametophyte axes. The gametophytes are diminutive, with stems that have been traced over 6 mm in length. The stems range from 0.1 mm to 0.2 mm in diameter and branch frequently, at ca. 270 µm intervals, with such intervals of dense branching separated by ca. 600 µm long segments devoid of branches. Stems are densely-leafy (ca. 23 leaf bases/mm of stem) with phyllotaxis that appears to be helical. Leaves are symmetric, 500 µm wide at the base, up to 900 µm in maximum width, and at least 1.0 mm long. They are unistratose throughout, plicate, and bear three strong costae. Laminal cells are isodiametric to slightly elongated (20-30 µm long) in the plane of the leaf. Alar cells, present in small numbers, are globose, 30-40 µm in size. Leaf margins are abaxially recurved and undifferentiated from the lamina in transverse section. The central costa consists of up to 12 narrow (5.5-9.5 µm diameter), long (50-90 µm) cells arranged in up to three layers. Lateral costae consist of up to 9 cells similar in anatomy to those of the central costa. One of the gametophytes bears numerous antheridia singly or in pairs, at the tips of lateral branches or along the main axis, either on very reduced branches or nearly sessile. Perigonial shoots are cylindrical and sharply truncated, ca. 100 µm in diameter; their leaves are erect, ovate with tapered tips, unistratose, ecostate, and they overtop the antheridia. The antheridia are oblong-cylindrical and borne on triseriate stalks. The presence of costae, along with the frequency of branching and lateral position of antheridia (both of which are indicative of a pleurocarpous moss), suggest placement in superorder Hypnanae. However, the combination of tri-costate, strongly plicate, and unistratose leaves sets this new moss apart from all extant and fossil bryophytes. This is an important addition to the extremely short list of anatomically preserved pre-Tertiary mosses, and marks a beginning in the study of the rich bryophyte flora of the Early Cretaceous Apple Bay locality. Furthermore, this Apple Bay moss represents one of the few occurrences of antheridia documented in fossil mosses.

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

British Columbia.

Presentation Type: Oral Paper:Papers for Sections
Session: 9
Location: Union A/Hyatt
Date: Monday, July 9th, 2012
Time: 10:45 AM
Number: 9002
Abstract ID:598

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