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RE: Peering at review



Ken Carpenter wrote:
 
> > but there is absolutely NO evidence of the existence of these 
> > critters.
>
> sorry, but you cannot use negative evidence to "prove" a point. Prior to
> the rather recent discovery of feathered dinosaurs, it was argued from
> negative evidence that no dinosaurs had feathers.

I take your point.  However, in the case of "feathery dinos" there was no
evidence either way; for the vast majority of theropods, no integument at
all was preserved, making either interpretation (feathery or scaly
integument) lacking in direct supporting evidence.  The "negative evidence"
cut both ways in this case.  Typological preconceptions filled the vacuum,
and therefore kept theropods featherless until the discovery of the Liaoning
taxa.

Hypothetical scenarios such as BCF fall into a different category.  True,
the absence of Triassic arboreal basal dinosaurs with aerial capabilities
does not *disprove* BCF.  However, the available evidence supports a
contrary phylogenetic hypothesis: the origin of birds from derived theropod
dinosaurs of the clade Maniraptora.  Thus BCF has two burdens to overcome:
why existing phylogenies are incorrect, and why we should believe that there
is a ghost lineage of tree-dwelling basal dinosaurs that gave rise to birds
and terrestrial dinosaurian clades.



Tim