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Re: Greg Paul is right (again); or "Archie's not a birdy"



> Wouldn't it have been AT LEAST equally cool to have reported this
> study under the headline Velociraptor Was A Bird?

Probably more cool, but I think less useful to both the science and
the public's understanding of it.

Birds are a living group of animals (that's sure what Linneaus meant
when he named them) and their most recent common ancestor (and
associated descendants).  Once we start tossing in taxa further from
the crown the word becomes more and more misleading.  Birds are known
to have only one working ovary as their primitive condition...is this
true of Archaeopteryx? Velociraptor?  What about the palatine?  It was
assumed (and even described from a poorly preserved version) as having
the "avian condition" in Archaeopteryx, when better data showed it has
the more primitive tetraradiate palatine.  In fact, outside of
feathers (which we now know goes far beyond Archaeopteryx) there is
almost nothing about it that makes it terribly like crown-group birds.

Researchers have already shown they don't do much better than the
public when it comes to getting passed the sort of typological
thinking that comes with taking a traditional crown-based name and
extending it down the tree.  Until very recently it was almost
impossible for Archaeopteryx to be found anywhere else...not because
of an inherent lack of data, but because up until the last year or two
almost everyone based their phylogenetic studies on one of two formats
that totally hinged on assumptions about Archaeopteryx being a bird:

1) Study where "birds" are nested - So you have extensive "non-avian"
theropod sampling, perhaps a few basal dinosaurs, but "birds" are
Archaeopteryx + Confusciousornis (or something similar).  It was
considered a huge breakthrough when people finally started tossing in
Jeholornis or the occasional enantiornithine.

2) Study the relationships of "early birds" - in this model you had
extensive sampling of theropods closer to modern birds than
Archaeopteryx, but perhaps Velociraptor and Allosaurus as an outgroup.

So in essence we've been failing to seriously test the position of
Archaeopteryx relative to "birds" and other coelurosaurs for the first
couple decades of the use of cladistics became mainstream in dinosaur
phylogenetics (which I'll define as the 1986 Gauthier paper on
saurischian monophyly).  And there seems to be no other reason than
our fixation on Archaeopteryx as somehow being the linchpin for birds
(Aves), which it never should have been.

I know that some people worry that this will create some sort of
unspecified havoc with the public ("Congress had to postpone the debt
ceiling issue today as they took up HB155GA: 'Is Archaeopteryx a
Bird', which has widespread bipartisan support").  Instead I urge
paleo workers to see this as our "Pluto Moment".  Teachable moments
like these, where the public is forced to encounter counter-intuitive
scientific ideas, are the greatest pedagological gift we can have.
Anyone asking an astronomer why Pluto isn't a planet in effect asking
"So why IS something a planet?", which in the hands of a good educator
is pure gold.

Likewise, any interested/concerned person asking why Archaeopteryx
isn't a bird "anymore" has just asked (with a genuine interest) to
know more about classification and how we study relationships.  Let's
embrace that moment, rather than expressing concern because, for
goodness' sake, someone might ask questions because of it(!!).

/end soapbox

-Scott

On Wed, Jul 27, 2011 at 3:36 PM, Mike Taylor <mike@indexdata.com> wrote:
> On 27 July 2011 18:34, Mike Keesey <keesey@gmail.com> wrote:
>> On Wed, Jul 27, 2011 at 10:20 AM, Thomas R. Holtz, Jr. <tholtz@umd.edu> 
>> wrote:
>>>
>>> An Archaeopteryx-like theropod from China and the origin of Avialae
>>>
>>> Xing Xu,         Hailu You,      Kai Du  & Fenglu Han
>>> Nature 475, 465–470 (28 July 2011) doi:10.1038/nature10288
>>> Received 16 November 2010 Accepted 10 June 2011 Published online 27 July 
>>> 2011
>>>
>>> Archaeopteryx is widely accepted as being the most basal bird, and
>>> accordingly it is regarded as central to understanding avialan origins;
>>> however, recent discoveries of derived maniraptorans have weakened the
>>> avialan status of Archaeopteryx. Here we report a new Archaeopteryx-like
>>> theropod from China. This find further demonstrates that many features
>>> formerly regarded as being diagnostic of Avialae, including long and
>>> robust forelimbs, actually characterize the more inclusive group Paraves
>>> (composed of the avialans and the deinonychosaurs). Notably, adding the
>>> new taxon into a comprehensive phylogenetic analysis shifts Archaeopteryx
>>> to the Deinonychosauria. Despite only tentative statistical support, this
>>> result challenges the centrality of Archaeopteryx in the transition to
>>> birds. If this new phylogenetic hypothesis can be confirmed by further
>>> investigation, current assumptions regarding the avialan ancestral
>>> condition will need to be re-evaluated.
>>
>> Very cool!
>>
>> Yet another reason why the definition of "Aves" should not rest on
>> _Archaeopteryx_.
>
> Really?
>
> Wouldn't it have been AT LEAST equally cool to have reported this
> study under the headline Velociraptor Was A Bird?
>
> -- Mike.
>



-- 
Scott Hartman
Scientific Advisor/Technical Illustrator
(307) 921-9750
website: www.skeletaldrawing.com
blog: http://skeletaldrawing.blogspot.com/