Re: Pleistocene & K/T extinctions

[John Alroy <jack@homebrew.uchicago.edu>]

        After "lurking" for a few days I realize that this list is  
not intended for long flame wars about mammal extinctions, so I am  
going to try to keep this short (not that this is likely to succeed).

1) Europe, Asia, Africa. If you want to check into this just look at  
P. S. Martin and R. G. Klein (eds.), Quaternary extinctions: a  
prehistoric revolution. I am not going to get into this because I  
feel like the case for anthropogenic "mass" extinctions of large  
vertebrates is iron-clad. Just look at the record for Pacific  
islands. I also want to reiterate that there is NO strong evidence  
for raised extinction rates of a) marine macroinvertebrates, b)  
marine microfossils, c) terrestrial plants, or d) insects in the  
terminal Pleistocene on ANY continent, hence, the climate-driven  
models are hopeless. Meanwhile, there are plenty of large-vertebrate  
extinctions on every continent and island, always coincident with the  
arrival of humans or somewhat thereafter. Check the recent extinction  
symposium volume in Philosophical Transactions of the Royal Society  
if you want more references (vol. 344 no. 2). There are plenty of  
others elsewhere. I think it's sad that so many competent scientists  
want to believe humans (or at least "stone age" humans) were harmless  
to ancient ecosystems. Can we at least agree that humans are causing  
serious ecological problems in the present? 


2) I am not going to get into a flame war over whether Neanderthals  
are "H. sapiens neanderthalensis" or "H. neanderthalensis" or about  
the multi-regional model, which I don't have strong feelings about.  
Nobody's arguing for a SOLE origin of modern H. sapiens from  
Neanderthal stock, so this is a side-issue. A relatively large  
population increase of humans in Europe around 40,000 and again  
around 10,000 years should hardly be controversial. There should be  
no great problem accounting for mammal extinctions in Europe by  
pointing to human migration patterns, population increases, and  
cultural innovations.

3) I am not going to get into a flame war about the U of Chicago. For  
the record, we have had about 20 Ph.D. students pass their prelims in  
"analytical" paleobiology over the last 10 years, and every one of  
them has done hands-on work with specimens. A majority have  
undertaken substantial field work as well. I am not a Raup and  
Sepkoski clone, and if you don't believe me check my publications  
(Paleobiology 18(3), 20(2); two papers in upcoming issues of  
Systematic Biology; December issue of Behavioral and Brain Sciences;  
numerous abstracts in GSA and SVP abstracts volumes). Most of my  
research is on phylogenetic theory and biochronologic theory. I have  
done plenty of work with "real" fossils, measuring several thousand  
hipparionine specimens in five different countries. This work is  
mostly unpublished but won't be for long. I think it's unfortunate  
you feel some need to call my credentials into question. I hope you  
don't feel I have done the same to you; I certainly didn't intend to  
do so.

4) There shouldn't be any need to continue bickering about the case  
for a rapid mass extinction at the K-T boundary. There is plenty of  
evidence for plant macrofossils, terrestrial vertebrates, marine  
macroinvertebrates, marine microfossils, etc. One or another study  
may be flawed, but at this point gradualists have an awful lot of ad  
hoc arguing to do (and, sadly, seem to be all too willing to do it).  
There's no point in arguing about all this if you don't think the  
Signor-Lipps effect is important and somehow are able to look at a  
nominally complete section showing a huge mass extinction in less  
than one meter and still think nothing too unusual happened (e.g,.  
Keller et al.'s study of the Mimbral section, latest issue of  
Palaios). As for dinosaurs, I stick with the conclusions of Sheehan  
et al. (1991: Science 254,835) that there is NO evidence for gradual  
extinction, based on a careful statistical analysis of a large number  
of in situ specimens. Counter-arguments of Williams (1994: J Paleont  
68,183) are unconvincing, and I will argue them point for point if  
you really care.
        Once again, I take Dr. Schwimmer's word that many interesting  
things happened in the oceans during the Maastrichtian. This is not  
to the point of whether a rapid extinction happened or whether a  
large asteroid impact happened.

5) I want to make it clear that I have the utmost respect for "field"  
paleontologists who collect the biostratigraphic and alpha taxonomic  
data all the rest of us rely upon. I know full well what is involved,  
having spent the last eight years reading the mammal paleo literature  
in order to revise the North American mammal time scale. I also think  
there is a place for theorists and quantitative analysts, and it is  
time that paleontology stopped embarassing itself in front of the  
scientific community by arguing this point. A discipline with no  
methods, models, theories, and quantitative analyses would be a  
rather sorry discipline.
        As for objectivity, I think it's clear from this debate that  
there's precious little to be had whenever the topic turns to  
media-friendly issues like the end-Pleistocene, the K-T, or  
dinosaurs. Please, let's at least not squabble about which of us is  
more "objective."

        Because few or none of these issues have anything to do with  
the subject of this list, I would be willing to continue this  
discussion via private e-mail instead of wasting more band-width on  
it. I apologize to the folks whose patience is wearing thin.