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Re: What the fossil record tells us about trends in pterosaur diversity
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.
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.
Michael Habib, M.S.
Center for Functional Anatomy and Evolution
Johns Hopkins School of Medicine
1830 E. Monument Street
Baltimore, MD 21205
(443) 280 0181