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Abstract Detail

Paleobotanical Section

Atkinson, Brian [1], Stockey, Ruth [1], Rothwell, Gar [1].

New evidence for the radiation of basal Cupressaceae.

Evolutionary relationships of taxodioid Cupressaceae are incompletely resolved. This is due, at least in part, to an evolutionary radiation during the Early Cretaceous that was followed by a high rate of extinction within the family. Many of these now extinct conifers share a variety of characters that are similar to the extant Cunninghamia lanceolata. Two anatomically preserved Cunninghamia-like seed cones recently have been discovered in Lower Cretaceous sediments of British Columbia. Both specimens are attached to vegetative shoots. The vegetative remains are incompletely preserved, but are similar to cunninghamioids by having helically-arranged, needle-like leaves with a single vascular bundle, one or more adaxial resin canals, and a band of centrally-located transfusion tissue. Seed cones are ovoid with helically-arranged bract-scale complexes. The bract and ovuliferous scale are highly fused with the majority of the complex apparently consisting of bract tissue. The ovuliferous scale is most clearly identified by three free apical lobes or tips located on the adaxial side of the bract. There are typically three inverted seeds borne on the adaxial side of the ovuliferous scale. Each seed is attached at the base of an apical lobe of the ovuliferous scale. Seed cones appear to be assignable to the cunninghamioid genus, Hughmillerites by virtue of having 1) ovoid shape, 2) ovuliferous scale represented by three separate tips, 3) typically three seeds per scale, 4) interseminal ridges between seeds, 5) one resin canal at the origin of the bract-scale complex, 6) discontinuous resin canal system in the bract, and 7) resin canals adaxial to the vascular strand in the bract. The new seed cones differ from the type species, H. juddii, by having 1) continuous central resin canal system from the axis to the bract, 2) lateral resin canals within bract, 3) smaller seed size, and 4) different histological features of the ground tissues. The new cones represent a second species of Hughmillerites, the oldest anatomically preserved cunninghamioid cone described to date. This discovery increases the diversity of Late Jurassic and Cretaceous cunninghamioid Cupressaceae, thus emphasizing that living cunninghamioids are a relict of a once far more geographically widespread and diverse clade.

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1 - Oregon State University, Department of Botany and Plant Pathology, 2082 Cordley Hall, Corvallis, OR, 97331, USA

seed cone anatomy.

Presentation Type: Oral Paper:Papers for Sections
Session: 3
Location: Melrose/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 9:30 AM
Number: 3006
Abstract ID:449
Candidate for Awards:Isabel Cookson Award

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