[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: 11th specimen of Archaeopteryx

Jaime, I pretty much agree with everything you've said.
_Archaeopteryx_ deserves its iconic status.  _Archaeopteryx_ is
certainly a mosaic, in the sense that it combines a highly derived
modern avian aerodynamic integument with (by avian standards) a highly
"primitive" osteology.  However, given that archaeopterygids represent
merely one lineage of paravians that employed their feathers for
aerial locomotion, I think it's dangerous to view _Archaeopteryx_ as
an aerodynamic precursor to modern bird flight.

Ironically, close examination of _Archaeopteryx_ has actually served
to overturn some of the long-held assumptions about the behavior of
the first 'birds':

Examination of the shoulder joint indicates that _Archaeopteryx_ was
incapable of flapping flight.

Examination of the pes shows that the hallux was fairly short and not
reversed, contradicting what one would expect in a perching bird.

Examination of the entire skeleton shows beyond doubt that
_Archaeopteryx_ was not specialized for an arboreal lifestyle.

IMHO, the fossil evidence points to a "long-fuse" development of the
modern avian flight apparatus.  Over a long period of time, and within
multiple lineages, paravians were engaged in aerial behavior that did
not qualify as true powered flight.  Various pre-ornithothoracean
clades (microraptorines, archaeopterygids, jeholornithids,
confuciusornithids, sapeornithids, etc) probably included parachuters
and gliders, plus forms that flapped to a minimal degree (such as for
undulating "flight").  But it was only at or close to the level of
Ornithothoraces that true flapping flight appeared - at least, that's
what the current evidence points to.  For that reason, paying too
close attention to _Archaeopteryx_ in a phylogenetic or aerodynamic
context could be dangerous.



On Fri, Oct 21, 2011 at 5:37 PM, Jaime Headden <qi_leong@hotmail.com> wrote:
>   Archie remains the cornerstone taxon to avian evolution on both an 
> historical level (as the key piece in the classic debates over avian origins 
> and phylogeny) and actual experiential level (the public has, because of the 
> historical aspect, more familiarity with these specimens and the acclaim they 
> brought to paleontology itself). Thus it remains a particularly valuable 
> element of education and discussion. It is also one of very few taxa whose 
> every specimen is known so well, in detail, and by particular monicker to 
> people who are not even specialists, a feat only approached by *Tyrannosaurus 
> rex*. The taxon has gained the classic monicker of "Archie," and it remains 
> used to this day. I do not think its impact is waning despite its decreasing 
> evolutionary significance, but that with the discussion around the 
> Thermopolis and now this new specimen, the acclaim will only increase. 
> Moreover, the material remains a viable piece of data in reconstructing 
> variability of "avian" evolution due to the integument and osteology in a 
> lagerstätt, and one from Germany where in the past two years any discussion 
> of avian origins has focused in Liaoning Province.
>   It should be important and telling that, despite it's seeming lack of being 
> a true "urvogel," Archie remains interesting due to the apparently unique 
> acquisition of features that nonetheless appear in other birds, part of the 
> basal mosaic of avian evolution, the root of Avialae, and this continues to 
> make Archie functionally important in an evolutionary as well as 
> biomechanical sense.
>   Although, it is just a dumb theropod to some ;).
> Cheers,
>  Jaime A. Headden
>  The Bite Stuff (site v2)
>  http://qilong.wordpress.com/
> "Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)
> "Ever since man first left his cave and met a stranger with a
> different language and a new way of looking at things, the human race
> has had a dream: to kill him, so we don't have to learn his language or
> his new way of looking at things." --- Zapp Brannigan (Beast With a Billion 
> Backs)
> ----------------------------------------
>> Date: Fri, 21 Oct 2011 17:19:12 +1100
>> From: tijawi@gmail.com
>> To: dinosaur@usc.edu
>> Subject: Re: 11th specimen of Archaeopteryx
>> Heinz Peter Bredow <hpbredow1956@googlemail.com> wrote:
>> > It contains a report about an 11th specimen of Archaeopteryx,
>> > with very well preserved bones and feathers but no skull.
>> >
>> > This specimen will be displayed with some other specimens of Archaeopteryx
>> > at the end of this month at the Münchner Mineralientage.
>> The importance of _Archaeopteryx_ to the evolution of flight has been
>> receding over the past decade - long before the phylogeny of Xu et al.
>> (2011) relegated it to the deinonychosaurian branch (which may change
>> at some point in the future).
>> Archie may actually have little relevance to the origin of the modern
>> avian flight apparatus. The flight abilities of Archie were not only
>> exceedingly weak, but with its long tail adorned with a "rectricial
>> frond" it probably represents a novel form of flight, very different
>> to that of modern birds. It is possible that archaeopterygids,
>> microraptorines and jeholornithids each represent separate experiments
>> in aerial flight behavior, none of which was ancestral to the modern
>> avian mode of flight. Short-tailed proto-birds like _Sapeornis_ might
>> be far more relevant to how modern birds came to fly - and there are
>> literally dozens of _Sapeornis_ specimens.
>> Of course, none of this detracts from the discovery of another Archie
>> specimen. Looking forward to the paper.
>> Cheers
>> Tim