Early Tertiary Chamaecyparis Spach from Axel Heiberg Island, Canadian High Arctic

• Published in: Canadian Journal of Botany
• Main Authors: Kotyk, M EA, Basinger, James F, McIver, Elisabeth E
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2003
• Subjects: Arctic; Axel Heiberg Island; Canada; Canadian Arctic Archipelago; Eureka; Eureka Sound; Heiberg; Arctic Archipelago
• Online Access: http://dx.doi.org/10.1139/b03-007; http://www.nrcresearchpress.com/doi/pdf/10.1139/b03-007

Exquisitely preserved fossil remains of Chamaecyparis Spach (Cupressaceae) have been recovered from Middle Eocene sediments of the Buchanan Lake Formation, Eureka Sound Group, of Axel Heiberg Island, Canadian Arctic Archipelago. Foliage consists of flattened, frondlike sprays considered typical for the genus. Leaves are decussate, scalelike, imbricate, appressed, and persistent. Seed cones are globose to subellipsoid, are borne on leafy peduncles, and bear 8–12 woody, peltate cone scales in a decussate arrangement. Seeds are two or more per scale, and winged. Within the genus, this fossil is most similar to extant Chamaecyparis pisifera (Siebold & Zucc.) Endl. of Japan, although the suite of features found in the fossil does not occur in any single living species of the genus. These fossil remains are assigned to a new species, Chamaecyparis eureka Kotyk sp. nov. A review of the fossil record indicates that Chamaecyparis eureka is the oldest known member of the genus, as the Late Cretaceous taxon Chamaecyparis corpulenta (Bell) McIver appears most closely related to Cupressus nootkatensis D. Don [= Chamaecyparis nootkatensis (D. Don) Spach], and should therefore be excluded from the genus Chamaecyparis. As revealed by the fossil assemblages of the Buchanan Lake deposits, Chamaecyparis was an uncommon constituent of lowland, swamp–forest communities growing at high paleolatitudes (about 78°N) during a period of global warmth prior to the onset of global climatic deterioration that led to Late Cenozoic glaciation. It was one of the few evergreen taxa in a largely deciduous broad-leaved and coniferous vegetation of early Tertiary regions in the far north.Key words: fossil, Tertiary, Chamaecyparis, Cupressaceae, Arctic, Canada.