Re: Magnosaurus & matrilineal dinosaurs

["Steve Brusatte" <dinoland@lycos.com>]

On Thu, 20 Dec 2001 13:46:39  
 Jaime A. Headden wrote:
>David Marjanovic (david.marjanovic@gmx.at) wrote, in reply to Pickering:
>
><In many species, especially predatory ones AFAIK, the females are 
>considerably larger.>
>
>  I would like to see evidence for this assumption. It is my understanding 
> that as of the main
>line of evidence supporting this (Larson, 1995, 1997) a recent list-member's 
>in press publication
>(Brochu, in press) would seem to suggest that there is no way to securely mark 
>a "male" or
>"female" label to that skeleton, or in fact apply it to others. What appears 
>to indicate male and
>female morphs in ceolophysids (robust and gracile) does not compare to actual 
>size disparities
>(Raath, 1980; Colbert, 1989) and ceratopsid variation is based almost soley on 
>horn and facial
>morphology (Sampson, 1995, 1997; Tanke has something in prep on this, as well) 
>and not size. In
>fact, there is no real data for size variation as an indication of gender 
>except for
>tyrannosaurines, and this is based on 1) sample size and 2) inference from 
>crocodylians which, as
>Brochu (onlist and in press) has said, is not entirely correct.

I don't know much about HP Brochu's paper, and I certainly don't want to 
speculate here.  However, in a lecture he gave at the Field Museum last year 
(during the unveiling of Sue) he discussed many of the points Jaime mentioned 
above.  I hope that he includes much of what he spoke of in his paper.  

In regards to a few comments David mentioned in previous posts about predatory 
birds, HP Brochu also discussed size differences between birds of prey and 
other predatory birds at his lecture.  Much of this is covered in an article I 
wrote last year for Fossil News and Dinosaur World (Debus and Brusatte, 2000).  
Don Glut also includes a few paragraphs on it in his most recent Dinosaurs: The 
Encyclopedia supplement.  

Basically, HP Brochu examined specimens of modern birds housed in the Field 
Museum's collections and found that some of his data cast doubts on Larson's 
conclusions.  Hopefully he will also include some of this information in his 
upcoming paper, and for that reason I will not further speculate here.

Steve

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