THE EVOLUTIONARY HISTORY OF Larix, Picea, and Pseudolarix (PINACEAE) BASED ON FOSSILS FROM THE BUCHANAN LAKE FORMATION, AXEL HEIBERG ISLAND, N.W.T., ARCTIC CANADA
Date
1993
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ORCID
Type
Degree Level
Doctoral
Abstract
Exquisitely preserved fertile and vegetative remains of Larix, Picea, and Pseudolarix have been recovered from middle Eocene sediments of the Buchanan Lake Formation on eastern Axel Heiberg Island, Canadian Arctic Archipelago. These remains, as well as a review of the fossil record of Larix, Picea, and Pseudolarix, provide a basis for examination and interpretation of the evolutionary and biogeographic history of these representatives of the Pinaceae. The quality and large number of specimens available for study have provided the opportunity to study, in detail, the morphological features of the seed cones. The results indicate that the bracts, together with other features of the cones, are species specific and useful for the identification and separation of fossil, as well as living representatives of these genera. On the basis of seed-cone morphology, one species of Larix, three species of Picea, and two species of Pseudolarix are recognized from the Axel Heiberg Island deposits. The spatial and temporal distribution patterns of Larix, Picea, and Pseudolarix fossils indicate that displacement of taxa between North America and Eurasia likely occurred through Beringia, and that the establishment of these genera in Europe appears not to have occurred until Miocene or Pliocene time, once the climate had sufficiently cooled.
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Degree
Doctor of Philosophy (Ph.D.)
Department
Graduate Studies and Research
Program
Geological Sciences