RE: Steadman's review of Mesozoic Birds

["Tim Williams" <twilliams_alpha@hotmail.com>]

John Pourtless wrote:

> I have watched and participated in this fracas for about a decade now.  And 
> in that time I have abandoned the thecodont hypothesis to which I 
> previously held, but I remain deeply troubled by the tone of the debate 
> amongst professionals and spectators such as myself.

I have to say (and it saddens me to say this) that this is part-and-parcel 
of scientific debate.  Every field of science has its topics that generate a 
surprising amount of acrimony.  To give another example... If you've tuned 
in to the life-on-Mars debate, you'll know that central to this debate is a 
certain Martian meteorite (ALH84001) found on Antarctica.  This meteorite, 
which is of undoubted Martian origin, contains microscopic crystals of 
magnetite that are of a shape and size uncannily similar to those produced 
biogenically by certain bacteria on Earth.  The debate over whether the 
magnetite contained in the Martian meteorite is indeed biogenic (and 
therefore indicative of past or present life on the Red Planet) is one of 
the most heated debates I have seen.  (I have heard that some scientists are 
no longer on speaking terms.)

Vitriolic debate also occurs in other areas of paleontology - as anybody who 
is familiar with the opposing theories on the origin of _Carcharodon_ (the 
great white shark) will attest to.

As for the birds-are-dinosaurs debate, this has to be one of the most 
lopsided debates in the history of science.  The notion that birds and 
maniraptorans are not really theropods, but a separate lineage that evolved 
independently from other theropods, is utterly bewildering.  Mickey is 
right: this does have an air of desperation to it.

>  It is nothing of the sort.  I merley wish to indicate that cladistics, 
> much like molecular systematics, is not the universal panacea for 
> ornithological systematics.

Molecular systematics actually employ cladistic methodology.  Nucleotides 
(for genes or RNA) and amino acids (for proteins) are the characters that 
are used.  But I would agree wholeheartedly that molecular analyses are not 
the panacea for resolving phylogenies (for birds or anything else).


Tim

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