Diversity among Taxodioid Conifers: Metasequoia foxii sp. nov. from the Paleocene of Central Alberta, Canada

Abstract

A single species of taxodioid conifers is among the dominant floristic elements at two stratigraphically contemporaneous Paleocene fossil localities in central Alberta, Canada. More than 10,000 compression specimens, including oppositely branched stems, vegetative shoots with decussately arranged leaves, pollen cones, pollen, ovulate cones, seeds, and seedlings, provide data for reconstructing a new species of Metasequoia. An in situ permineralized stem provides information about wood structure and suggests that the plant 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 combination of characters from several organs demonstrates the occurrence of a distinct species, M. foxii sp. nov. The diagnostic combination of characters for this species includes leaf size, pollen cone length, ovuliferous cone scale arrangement, seed size and shape, and characters of the seedlings. Ranges of variation in characters of the new species are compared to those of the currently recognized, well‐known species of Metasequoia, M. glyptostroboides, M. occidentalis, and M. milleri, and evolutionary diversification within the genus is considered.