Re: Were dinosaur ecosystems continent-sized? (resend)

[Denver Fowler <df9465@yahoo.co.uk>]

From: GUY LEAHY <xrciseguy@q.com>

>If one limits the comparison to Alberta/Montana/Wyoming, I would agree these 
>faunas appear pretty similar, though there may be small degrees of 
>provincialism.  

If you want to demonstrate provincialism you have to demonstrate that the 
faunas are exactly contemporaneous and that they are not just slightly 
different due to ontogenetic variation. My thesis is constructing a high 
resolution regional chronosratigraphic framework for the Lance/Hell 
Creek/Frenchman/Scollard and I'll say that there is no support for any 
latitudinal provincialism , but there may be some slight variation in faunal 
composition depending on how near you are to the coast... I thing Greg Wilson 
detected this in the mammalian fauna.

>... and most of the dinosaur-bearing units in the southwest appear to be 
>somewhat older than Hell Creek/Lance/Scollard taxa (the North Horn Fm. is an 
>exception)

Evidence for age of the SW units is sparse, but we can say that there isn't any 
evidence for the K-T boundary in any of the units, including the North Horn. 
The only firm date that exists is 69Ma for the Javelina, but other lines of 
evidence exist for the NM and UT Fms suggesting both are not even Late 
Maastrichtian, especially not the dinosaur bone bearing horizons of the North 
Horn that lie low in the Fm.

>By contrast, we can directly compare faunas of Campanian age from Alberta and 
>Utah (DInosaur Park and Kaiparowits Fms.)  Both units are well constrained by 
>radiometric dates, and are of similar age.  Though broadly similar in general 
>appearance, at the species level, there appears to be no similarity in the 
>dinosaur faunas.  

The problem with the provincialism hypothesis is that it is confounded by lack 
of high-resolution stratigraphic and ontogenetic analysis. I can certainly 
believe that there is some provincial signal, and this seems to be supported by 
some of the described taxa, but others (including G. monumentensis) are 
stratigraphically separated, and if anything are strong evidence against the 
provincial 
s. Species resolution for dinosaur taxa seems to be generally 300ky or less; so 
using 2Ma time slots for comparison is not going to yield any useful result, 
indeed it will probably produce the wrong result. My thesis is (in part) 
dealing with this issue.



> Date: Fri, 23 Apr 2010 03:37:11 +0000
> From: df9465@yahoo.co.uk
> To: dinosaur@usc.edu
> Subject: Re: Were dinosaur ecosystems continent-sized? (resend)
> 
> I suppose I should also add that the Scollard fauna is included in the 
> dataset. 
> 
> The incorrect taxa include:
> 
> The Aguja sometimes being listed as Maastrichtian: I understand the reasons 
> why this is listed, but this is based on an old interpretation of its age.
> Pentaceratops in the Maastrichtian (it's late Campanian only)
> Parasaurolophus in the Maastrichtian Kaiparowits (Kaiparowits is Campanian)
> Saurolophus in the Maastrichtian of New Mexico
> Chasmosaurus is not known from the Kirtland Fm
> Monoclonius is a dubius taxon.
> 
> It highlights the problems of using a dataset from the paleobiology database 
> (not the authors fault), as this database seems to include every suggestion 
> that has been made in the literature, some from before recognition of 
> accidental mixing of faunas, publication of ash dates, stratigraphic 
> reinterpretation etc.
> 
> But like I say, removal of problem taxa probably reinforces the conclusions 
> of the authors. The recent Longrich paper almost certainly underestimates the 
> age of the unit from which their specimen derives;making comparison with some 
> of the Canadian units not exactly even. 
> 
> There is evidence for latitudinal variation in dino faunas, but it is not 
> nearly as strong as has been suggested. The reasons for this are largely fine 
> details in stratigraphic and taxonomic interpretation, which is a big part of 
> my thesis (hopefully will get to present a little bit at SVP). I think that 
> Vavrek and Larson's result is right on the money: some indication of 
> small-provincialism in limited clades, but not rampant across the board.
> 
> -------------------------------
m
> -----------------------------------
> 
> 
> 
> ----- Original Message ----
> From: Denver Fowler <df9465@yahoo.co.uk>
> To: DML <dinosaur@usc.edu>
> Sent: Thu, 22 April, 2010 21:06:55
> Subject: Re: Were dinosaur ecosystems continent-sized? (resend)
> 
> If you check the datasets (sd01.xls), you'll find that faunas from Utah, New 
> Mexico, and Texas are included. However, a number of taxa have erroneous str
> tudy, since, if anything, removal of incorrect data reduces disparity between 
> northern and southern faunas.
> 
> 
> ----------------------------------
> Denver Fowler
> df9465@yahoo.co.uk
> http://www.denverfowler.com
> -----------------------------------
> 
> 
> 
> ----- Original Message ----
> From: GUY LEAHY <xrciseguy@q.com>
> To: Dinosaur Mailing List <dinosaur@usc.edu>
> Sent: Thu, 22 April, 2010 19:54:21
> Subject: Were dinosaur ecosystems continent-sized? (resend)
> 
> 
> Resent, this time in plain text... :-)
> 
> According to this analysis, yes:
> 
> http://www.mcgill.ca/newsroom/news/item/?item_id=116613
> 
> http://www.pnas.org/content/early/2010/04/05/0913645107
> 
> A couple of problems right off the top:
> 
> 1. No faunas from Utah, New Mexico or Texas are included in the dataset. 
> 2. The upper Maastrichtian Scollard fauna is not included, but the 
> lower-middle Maastrichtian Horseshoe Canyon fauna is...
> 
> It's an interesting coincidence in time this appears a few days after the 
> publication of a new pachycephalosaur (_Texacephale_), where the authors 
> suggest exactly the opposite scenario: 
> http://www.sciencedaily.com/releases/2010/04/100419132406.htm
> 
> Guy Leahy 
> 
> 
> 
> 
>