REVISED STRATIGRAPHIC RELATIONSHIPS WITHIN THE LOWER FORT UNION FORMATION (TULLOCK MEMBER, GARFIELD COUNTY, MONTANA, U.S.A.) PROVIDE A NEW FRAMEWORK FOR EXAMINING POST K–PG MAMMALIAN RECOVERY DYNAMICS
Author:
WEAVER LUCAS N.123, TOBIN THOMAS S.4, CLAYTOR JORDAN R.12, WILSON DEIBEL PAIGE K.25, CLEMENS WILLIAM A.6, WILSON MANTILLA GREGORY P.12
Affiliation:
1. Department of Biology, University of Washington, Seattle, Washington 98195-1800, USA 2. Department of Paleontology, Burke Museum of Natural History and Culture, University of Washington, Seattle, Washington 98195-1800, USA 3. Current: Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109, USA 4. Department of Geological Sciences, University of Alabama, Tuscaloosa, Alabama 35401, USA 5. Department of Earth and Space Sciences, University of Washington, Seattle, Washington 98195-1800, USA 6. University of California Museum of Paleontology, Berkeley, California 94720, USA
Abstract
ABSTRACTThe Hell Creek region of northeastern Montana is an excellent study system to explore the rise to dominance of mammalian faunas after the Cretaceous–Paleogene (K–Pg) mass extinction. The Tullock Member of the Fort Union Formation exposed in that region was deposited during the first 1.2 Ma after the Chicxulub bolide impact. Some aspects of post-K–Pg mammalian succession remain obscure, however, due to a lack of finer stratigraphic resolution between vertebrate fossil localities. Here, we present a new stratigraphic model for the lower and middle Tullock and identify a stratigraphic succession of five mammal-bearing sedimentary units that span the first ∼ 900 ka of the Paleocene. Most notably, we find that middle Tullock fossil localities, which were previously thought to be deposited by a single, large fluvial channel complex, are derived from two temporally and lithologically distinct sedimentary units: the Biscuit Springs unit (BS) and the Garbani channel (GC). The top of the GC is stratigraphically above the top of the BS, but in some places cuts through the entirety of the BS, a relationship that previously complicated interpretations of their relative age. This cross-cutting relationship reveals that the BS is older than the GC. Thus, the BS local fauna represents a potential intermediate between the older local faunas from the post-K–Pg ‘disaster' interval and the younger, more taxonomically/ecologically diverse GC local fauna. This new stratigraphic framework sets the stage for future studies focused on the pattern and timing of biotic recovery in the aftermath of the K–Pg mass extinction.
Publisher
Society for Sedimentary Geology
Subject
Paleontology,Ecology, Evolution, Behavior and Systematics
Reference75 articles.
1. Alroy, J., 1999, The fossil record of North American mammals: evidence for a Paleocene evolutionary radiation: Systematic Biology, v.48, p.107– 118. 2. Alvarez, L.W., 1983, Experimental evidence that an asteroid impact led to the extinction of many species 65 million years ago: Proceedings of the National Academy of Sciences of the United States of America, v.80, p.627– 642. 3. Archibald, J.D., 1982, A study of Mammalia and geology across the Cretaceous–Tertiary boundary in Garfield County, Montana: University of California Publications in Geological Sciences, v.122, p.1– 286. 4. Archibald, J.D., Clemens, W.A., Gingerich, P.D., Krause, D.W., Lindsay, E.H., and Rose,K.D., 1987, First North American Land Mammal Ages of the Cenozoic Era, inWoodburneM.O.(ed.),Cenozoic Mammals of North America: University of California Press, Berkeley, California, p.24– 76. 5. Bown, T.M. and Kraus,M.J., 1987, Integration of channel and floodplain suites, I, developmental sequence and lateral relations of alluvial paleosols: Journal of Sedimentary Petrology, v.57, p.587– 601.
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