RE: Fastovsky vs Archibald

["Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>]

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Phil Bigelow
>
>
>
> One point that should be emphasized is that no one (to my knowledge) has
> actually conducted a rigorous (e.g., non-anecdotal) sampling/statistical
> study of intraformational extinctions within the Hell Creek Formation.
>

Lillegraven, J.A. & J.J. Eberle. 1999. Vertebrate faunal changes through 
Lancian and Puercan time in southern Wyoming. Journal of
Paleontology 73:691-710.

Abstract
We summarize faunal changes through the thickest and one of the most complete 
records of terrestrial vertebrates spanning Lancian
( approximately latest Cretaceous) and Puercan ( approximately earliest 
Paleocene) ages, the type Ferris Formation in the Hanna
Basin, southern Wyoming. Observed faunal changes predate tectonic definition of 
local Laramide basins. Nonmammalian vetebrates
exhibit no major changes in taxonomic composition below the Lancian-Puercan 
boundary; diversity of non-avian dinosaurs remains high
within uppermost levels of the Lancian section. Nevertheless, dinosaurian 
extinction was not necessarily "catastrophic" within a
biologically relevant interval. Primitive condylarths appear locally above the 
highest known dinosaurs, probably as immigrants. At
least in this part of the North American western interior, the first 
evolutionary radiation of condylarths was subsequent to the
last appearance of dinosaurs, not synchronous with or prior to it. 
Niche-partitioning among condylarths is first recorded near the
boundary between Puercan Interval-zones Pu1 and Pu2 (early and middle Puercan 
time, respectively), by which time the first great
mammalian diversification of the Cenozoic had begun. Major experimentations in 
dental morphology and increasing ranges of body sizes
had developed within 400,000 years of the Lancian-Puercan boundary. We 
recognize no evidence suggesting that placental mammals were
"recovering" from events that led to demise of the dinosaurs. The true 
diversity of marsupials and condylarths precisely at the
Cretaceous-Tertiary boundary, throughout the western interior, remains unknown. 
We cannot, therefore, evaluate extensiveness of
competition, if any, at that time among members of the two groups.

Reviewed breifly on DML: http://dml.cmnh.org/2000Mar/msg00634.html

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
        Mailing Address:
                Building 237, Room 1117
                College Park, MD  20742

http://www.geol.umd.edu/~tholtz/
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