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Re: Archie a bird not a dino



"Dear gods, someone kill that Corbis graphics pseudo-Archie sculpture; because 
it is on a database accessible to the media it showsup all the time, despite 
the fact it looks nothing likch Archaeopteryx!!"

Well, that answers my question! Didn't think it looked right.

 
"Scepticism is the highest of duties; blind faith the unpardonable sin." 
~Thomas Henry Huxley


----- Original Message -----
From: "Thomas R. Holtz, Jr." <tholtz@umd.edu>
To: birdbooker@zipcon.net; dinosaur@usc.edu
Cc: vrtpaleo@usc.edu
Sent: Wednesday, 26 October 2011 8:24 PM
Subject: RE: Archie a bird not a dino

> From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu] 
> On Behalf Of Ian Paulsen
> HI ALL:
>  FYI:
> 
> http://www.guardian.co.uk/science/2011/oct/26/archaeopteryx-bird-family-tree

Dear gods, someone kill that Corbis graphics pseudo-Archie sculpture; because 
it is on a database accessible to the media it shows
up all the time, despite the fact it looks nothing likch Archaeopteryx!!

In any case:

The paper in question:
Lee, M.S.Y. & T.H. Worthy. 2011. Likelihood reinstates Archaeopteryx as a 
primitive bird. Biol. Lett. published online before print
October 26, 2011, doi:10.1098/rsbl.2011.0884

http://rsbl.royalsocietypublishing.org/content/early/2011/10/18/rsbl.2011.0884.full

The abstract:

"The widespread view that Archaeopteryx was a primitive (basal) bird has been 
recently challenged by a comprehensive phylogenetic
analysis that placed Archaeopteryx with deinonychosaurian theropods. The new 
phylogeny suggested that typical bird flight (powered
by the front limbs only) either evolved at least twice, or was lost/modified in 
some deinonychosaurs. However, this parsimony-based
result was acknowledged to be weakly supported. Maximum-likelihood and related 
Bayesian methods applied to the same dataset yield a
different and more orthodox result: Archaeopteryx is restored as a basal bird 
with bootstrap frequency of 73 per cent and posterior
probability of 1. These results are consistent with a single origin of typical 
(forelimb-pow
inonychosaur clade retrieved by parsimony is supported by more characters 
(which are on average more homoplasious),
whereas the Archaeopteryx-bird clade retrieved by likelihood-based methods is 
supported by fewer characters (but on average less
homoplasious). Both positions for Archaeopteryx remain plausible, highlighting 
the hazy boundary between birds and advanced
theropods. These results also suggest that likelihood-based methods (in 
addition to parsimony) can be useful in morphological
phylogenetics."

The punchlines to the paper:

"These include traits unique to Archaeopteryx and other birds, such as evenly 
spaced anterior maxillary teeth (character #89) teeth
and anterior chevrons with flattened plate-like base (#122; but see [19]), as 
well as traits unique to Xiaotingia, Anchiornis and
troodontids, such as anterior caudal vertebrae with distally tapering 
transverse processes (#373). Conversely, some of the
similarities between Archaeopteryx and deinonychosaurs, interpreted in the 
parsimony analysis as shared derived characters [3], need
to be reinterpreted as primitive characters of all birds and deinonychosaurs 
(paravians), secondarily lost in birds above
Archaeopteryx and Wellnhoferia. These include hyperextensibility of the second 
(= first functional) toe (character #323), a
posterior process on the ischium (#334) and a distally located obturator 
process (#167)."

And

"The results here do not demonstrate unequivocally that Archaeopteryx belongs 
with birds rather than with deinonychosaurs; bootstrap
support is only approximately 73 per cent, while the posterior probability of 1 
is tempered by arguments that Bayesian inference can
greatly overestimate support if the models implemented are inadequate [8,23]. 
Resolution of the precise position of Archaeopteryx
will likely require more empirical data such as new fossils or novel 
characters. The alternative placements of Archaeopteryx
highlight the closure of the morphological gap between birds and theropod 
dinosaurs [2-6,17,22], and also suggest that dramat
einterpretations of early bird evolution are not yet required. Furthermore, the 
more generally accepted tree, found with
likelihood-based methods (and the strong contrast with parsimony), suggests 
that likelihood-based phylogenetic methods should be
used more often in palaeontology and morphology [24], especially for large 
datasets [3] that have sufficiently large numbers of
characters to allow critical parameters in likelihood models to be robustly 
estimated."

Thomas R. Holtz, Jr.
Email: tholtz@umd.edu    Phone: 301-405-4084
Office: Centreville 1216            
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
http://www.geol.umd.edu/~tholtz/
Fax: 301-314-9661        

Faculty Director, Science & Global Change Program, College Park Scholars
http://www.geol.umd.edu/sgc
Fax: 301-314-9843

Mailing Address:    Thomas R. Holtz, Jr.
            Department of Geology
            Building 237, Room 1117
            University of Maryland
            College Park, MD 20742 USA 

> -----Original Message-----
> sincerely
> -- 
> 
> Ian Paulsen
> Bainbridge Island, WA, USA
> Visit my BIRDBOOKER REPORT blog here:
> http://birdbookerreport.blogspot.com/