Re: What the fossil record tells us about trends in pterosaur diversity

[David Peters <davidpeters@att.net>]

As in anything dealing with fractals, it depends entirely on your scale.

If you can divide the Triassic, Jurassic and Cretaceous each into  
three for a total of nine units, then the answers are pretty clear -  
with some allowance for an occasional Lazarus taxon (which has _not_  
popped up yet). If you want to get more specific, then it gets  
trickier. From this vantage point ~65my after the last of the  
pterosaurs, I wouldn't get more specific on scale.

The most interesting thing about current German and Chinese  
Lagerstatte is for whatever reason, they seem to have preserved some  
of the most interesting intervals in the fossil record where  
everything was changing.

And yes, to your point, these are just snaphots.

Best regards,

David Peters


On Nov 17, 2008, at 11:16 AM, Michael Habib wrote:

> David Peters wrote:
>
> > I disagree. Phylograms are particularly instructive.
>
> We can produce a topology, certainly, but if the results of Butler  
> et al. are accurate, then attempts to estimate ghost lineage  
> lengths and overall time calibrationsare more or less completely  
> muddied, meaning that you still can't produce an accurate estimate  
> of diversity through time.
>
> > BTW: various pterosaur genera of all shapes, sizes and niches were  
> > going extinct left and right long before the advent of birds.
>
> It seems that way, but again, if the apparent diversity of  
> pterosaurs in each interval is entirely taphonomic, how do we know  
> that's actually true?  It might be that only a very few of those  
> apparent extinctions are real, and we're truncating the last  
> occurance dates for many lineages.
>
> Cheers,
>
> --Mike
>
>
> Michael Habib, M.S.
> PhD. Candidate
> Center for Functional Anatomy and Evolution
> Johns Hopkins School of Medicine
> 1830 E. Monument Street
> Baltimore, MD 21205
> (443) 280 0181
> habib@jhmi.edu

David Peters
davidpeters@att.net