Archaeopterygid bird from China

[John Grehan]

> John,
>       While I do agree with you that the location of oldest fossil is
not
> "necessarily" near the origin of a family, I agree with Dick that an
Asian
> origin for Archaeopterygidae is presently the best hypothesis.  

On what basis is it the best hypothesis? What is the empirical evidence
that the family originated first in any part of its range as opposed to
any other? My point is that fossils themselves do not provide that
evidence and so the contention is not scientific. One might theorize
that the distribution of fossil ages is the result of sequential
migration from an original center of origin, but the pattern might also
be due to sequential differentiation of an ancestor that was already
widespread to encompass all localities.

We don't
> even know yet if this new genus is as old as Archaeopteryx anyway, so
I am
> certainly not basing my hypothesis on the age of the Chinese form.
> HOWEVER, the closest relatives to Archaeopterygidae (namely,
> Scansoriopteryx and Cryptovolans) also come from eastern Asia.

Meaning?
> 
>      I suspect that Archaeopterygidae may have never made it to North
> America (if so, they were probably derived spin offs as well).  And if
we
> DID find an early primitive member of this family in Antarctica, we
would
> have to completely rethink this hypothesis.  But frankly I doubt they
ever
> got anywhere close to Antarctica, because I know of no evidence at all
> that this family ever left Eurasia.  If one is discovered in South
America
> (where lots of interesting Mesozoic fossils are being found), I will
be
> frankly shocked and forced to reconsider, but I'm not going to hold my
> breath.
>   --- Cheers,
>              Ken

It's always possible that any group may have occurred at locations for
which there is currently no record. My point is that the center of
origin is more imaginary than real.

John
> ******************************************************
> John Grehan wrote:
>      It seems non scientific in that the fossils themselves do not
lead to
> the hypothesis.  The hypothesis comes from somewhere else.  For
example,
> why would one need to hypothesize that a taxon had its origin at or
near
> the location of the oldest fossil?  And how can any further fossils
'test'
> that proposition.  If one found an older Archaeopterygid bird in
> Antarctica, for example, one would still not be any the wiser about
the
> initial hypothesis, or even that a taxon has an origin associated with
any
> one particular location.