Diversity among taxodioid conifers: Metasequoia foxii sp nov from the Paleocene of central Alberta, Canada

A single species of taxodioid conifers is among the dominant floristic elem ents at two stratigraphically contemporaneous Paleocene fossil localities i n central Alberta, Canada. More than 10,000 compression specimens, includin g oppositely branched stems, vegetative shoots with decussately arranged le aves, pollen cones, pollen, ovulate cones, seeds, and seedlings, provide da ta for reconstructing a new species of Metasequoia. An in situ permineraliz ed stem provides information about wood structure and suggests that the pla nt was a canopy tree. As is characteristic of taxodioid conifers in general , most compressed organs of the new species are not specifically diagnostic when evaluated as isolated fragments of the sporophyte. However, a combina tion of characters from several organs demonstrates the occurrence of a dis tinct species, M. foxii sp. nov. The diagnostic combination of characters f or this species includes leaf size, pollen cone length, ovuliferous cone sc ale arrangement, seed size and shape, and characters of the seedlings. Rang es of variation in characters of the new species are compared to those of t he currently recognized, well-known species of Metasequoia, M. glyptostrobo ides, M. occidentalis, and M. milleri, and evolutionary diversification wit hin the genus is considered.