David Hone on the Cope's Rule paper

[Mike Taylor <mike@indexdata.com>]

Posted on David's behalf ...

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Dear DML-ers,

My thanks to Mike Taylor for posting this on my behalf. I have been 
away this last week or so, but I have seen a flurry of posts on the 
archives about my two recent papers. While there is far too much to 
reply to in detail (after all the comments flying around), there are a 
couple of points that I think have been misinterpreted or have got lost 
in the mix somewhere so I will address a couple briefly. (Comments on 
the Archosauromorph 'second paper' will follow shortly as a separate 
post).

Hopefully this won't stir up any more of a hornet's nest that already 
has been, but I guess we will see! People are of course welcome to 
contact me directly for further discussions etc.

Lee Hall seems unhappy with my testing of Cope's Rule (CR) apparently 
deeming it unnecessary. Frankly, this is much the point of this (and 
other) papers. CR is something often banded about with absolutely no 
testing what soever. Following Kingsolver and Pfennig (2004) and recent 
CR papers (including my own, but plenty more are out there - see Hone & 
Benton, 2005 for details) it is clear to me that CR has been massively 
overlooked. There is good evidence for the positive benefits of large 
size and for increase in sizes across lineages. This may often (see 
dinosaurs) be represented by a diversification event, rather than an 
active trend for large size (see pterosaurs), but it is there. CR is 
alive and well, and should not be dismissed until tested fully. So far 
it has been, at best, tested badly in a few lineages (look at the 
effects of different levels in Pterosaurs, but also see Alroy, 2000) so 
to say that I'm wasting my time seems to me (obviously) to be very well 
wide of the mark.

Mark Witton has commented on my apparent perpetuation of the 'all 
pterosaurs are fish eaters' myth. Mark, I actually agree with you. I 
have an application in for a project on trying to bust at least part of 
this myth (I am satisfied that many lineages are primarily piscivorous, 
and of course there are obvious exceptions like Anurognathus, 
Pterodaustro and Dsungeripterus). *However*, the bulk of the literature 
deals with the assumption that most pterosaurs were piscivorous, and 
without good evidence published to the contrary, that is what I am 
going on, and what I will refer to. Still, if nothing else, the vast 
majority of pterosaurs are at least known from marine / lacustrine 
environments and while that is not exactly compelling evidence for 
dietary preference, it is at least good circumstantial evidence.

Much has been made of the allusions towards competitive exclusions with 
birds. This needed including as it has been mentioned a number of times 
before (by Unwin among others) and so it is hard to ignore. I am not 
dumb enough to think comparing marine soarers like Pteranodon with 
inland small birds from the Jehol is a valid comparison (time, size, 
distribution, ecology so start with) BUT it is noticable that the drop 
off of small pterosaurs occurs as the birds begin to rise, and I would 
look more of a fool if I ignored that fact. It is not lost on me that 
the McGown and Dyke paper on this very subject was the next paper in 
the journal, but for what its worth I think that there is good evidence 
out there already, and on the way (from myself and others) that birds 
*may* have had a significant role in the decline of smaller (almost, 
but not quite, synonymous with rhamphorhyncoid) pterosaurs.

That will do that one for now! If Mike will indulge me, I'll address 
the Archosauromorph paper in a second mail so that those interested in 
CR are not bored by it and vice versa.

Thanks,

Dave
_______________________________________________
Dr David W.E. Hone
Bayerische Staatssammlung für Paläontologie und Geologie
Richard-Wagner-Straße 10
D-80333 München
Germany

Tel: +49 / (0)89 / 2180 6613
Fax: +49 / (0)89 / 2180 6601

www.askabiologist.org.uk