High-elevation late Pleistocene (MIS 6–5) vertebrate faunas from the Ziegler Reservoir fossil site, Snowmass Village, Colorado

Abstract

The vertebrate record at the Ziegler Reservoir fossil site (ZRFS) near Snowmass Village, Colorado ranges from ~140 to 77 ka, spanning all of Marine Oxygen Isotope Stage (MIS) 5. The site contains at least 52 taxa of macro- and microvertebrates, including one fish, three amphibian, four reptile, ten bird, and 34 mammal taxa. The most common vertebrate is Ambystoma tigrinum (tiger salamander), which is represented by >22,000 elements representing the entire life cycle. The mastodon, Mammut americanum, is the most common mammal, and is documented by >1800 skeletal elements making the ZRFS one of the largest accumulations of proboscidean remains in North America. Faunas at the ZRFS can be divided into two groups, a lake-margin group dating to ~140–100 ka that is dominated by woodland taxa, and a lake-center group dating to ~87–77 ka characterized by taxa favoring more open conditions. The change in faunal assemblages occurred between MIS 5c and 5a (vertebrates were absent from MIS 5b deposits), which were times of significant environmental change at the ZRFS. Furthermore, the ZRFS provides a well-dated occurrence of the extinct Bison latifrons, which has implications for the timing of the Rancholabrean Mammal Age in the region.

Late Quaternary vertebrates from the Upper Gunnison Basin, Colorado, and small-mammal community resilience to climate change since the last glacial maximum

“…The excavation history, stratigraphy, and taphonomy of these caves and their fossil assemblages are described below. These faunas supplement previous work on high-elevation middle Pleistocene faunas from montane regions surrounding the UGB (Barnosky, 2004; Sertich et al, 2014).…”

“…The deposits at Porcupine Cave (1.0–0.6 Ma) also span at least two glacial-interglacial cycles and provide a model for comparison of faunal turnover with climate change in alpine communities (Barnosky, 2004; Barnosky et al, 2004; Barnosky and Shabel, 2005). One other high-elevation site in Colorado at 2700 m, the Ziegler Reservoir site in Pitkin County, has produced a rich collection of fossil mammoths ( Mammuthus columbi ), mastodons ( Mammut americanum ), numerous other large and small vertebrates, and plant remains dating to ~130,000–70,000 yr BP (Sertich et al, 2014).…”

The easternmost occurrence ofMammut pacificus(Proboscidea: Mammutidae), based on a partial skull from eastern Montana, USA

“…How did the ranges of the two species fluctuate in response to environmental shifts throughout the Pleistocene? Apart from specimens of M. pacificus from Idaho, to our knowledge the described mastodon specimens geographically closest to MOR 605 are specimens of M. americanum from northern Utah (Miller, 1987) and northern Colorado (McDonald et al, 2010;Fisher et al, 2014). M. americanum remains from the Wasatch Plateau in Utah (Miller, 1987) and Snowmass in Colorado (Fisher et al, 2014;Mahan et al, 2014;Sertich et Fig.…”

Preserved Proteins from Extinct Bison latifrons Identified by Tandem Mass Spectrometry; Hydroxylysine Glycosides are a Common Feature of Ancient Collagen

“…(191-130 ky ago). The B. latifrons samples found at the Ziegler site date back ϳ120 ky, thus opening a previously unexplored window to the biology of extinct ice age North American fauna (51).…”

“…The finding was made during a construction project at the Ziegler Reservoir, a fossil site that was originally a lake formed at an elevation of ϳ2,705 m during the Bull Lake glaciations ϳ140 ky ago (49,51). The original lake area was ϳ5 hectares in size with a total catchment of ϳ14 hectares and lacked a direct water flow inlet or outlet.…”