Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1045273 | Quaternary Research | 2014 | 8 Pages |
Abstract
Pleistocene biogeography of conifer species is poorly known in much of western North America. We conducted morphological studies on 201 conifer cones and cone fragments recovered from Pleistocene sediments at the Ziegler Reservoir fossil site (2705Â m) near Snowmass Village, Colorado. The basin, formed ~Â 155-130Â ka, contains fossil-bearing lacustrine, palustrine, and colluvial sediments spanning approximately 85Â ka. Using a suite of morphological characters, particularly cone-scale bracts, we differentiated species of Abies, Picea, and Pseudotsuga. All fossil Abies specimens were assignable based on bract morphology to Abies concolor, which is currently absent from central Colorado (nearest populations are 160Â km southwest of the site). A. concolor occurs only in sediments of MIS 5d and 5c. Pseudotsuga menziesii and Picea engelmannii cones occurred in sediments corresponding to MIS 5e, 5d, 5c, and 5a. A fourth conifer species, occurring in sediments of MIS 5e, 5d, 5c, and 5a, is difficult to assign to any extant species. Bract morphology is similar to Picea pungens, which grows near the site today, but scale morphology is unlike P. pungens. These fossils may represent ancestral P. pungens, an extinct variant, or an extinct sister species.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geology
Authors
Dane M. Miller, Ian M. Miller, Stephen T. Jackson,