Re: BIRD CHARACTERISITICS

["Matthew Troutman" <m_troutman@hotmail.com>]

I have a few critisms of this lis.


>From: charger72@juno.com

>Subject: Re: BIRD CHARACTERISITICS

>
>I'm not sure what the diagnostic features would be, but to make sure
>everyone knows what we are talking about I will list the unique 
features
>of birds. Some of these features are shared by other animals, but they
>are distinctly avian characteristics.
>
>1) large sternum with a deep furcula (keel) attached to long ribs and
>elongated coracoid bones.
                                   
 The large sternum is seen in dromaeosaurs and the keel is called the 
carinate. The furcula is the "wishbone." And not all bird ribs are long, 
take for example the running ratites and some of the enantiornthines. 
The elongated coracoid is seen in Archaeopteryx just not to the level 
seen in enantiornthine birds and Ornithurae birds. 


>2) shoulder girdle rotated and shifted upward, even with the backbone.


 This is also seen in Archaeoperyx.

>3) elongated lower leg bones and a modified ankle (tarso-metatarsus)


 Do you mean when you talk about the tarsomeatarsus the one seen in 
ornithuraes? The kind of metatarsus seen in Archaeopteryx and is the 
same one as the one in enantiornthines.

>4) elongated ilium attached to at least 11 vertebrae and as many as 23.


 Enantiornthines have as few as six sacral vertebrae. 


>5) ischium and pubis point backward to make room for the sternum.


 No argument here except that Archaeopteryx is begining to show this 
feature.

>6) short body centered over the feet with breastbone between the knees.


 Actually the bird body is centered right behind the femora in some 
birds like woodpeckers. 

>7) shortened pygostyle tail.
 

Not in Mononykus and to a degree the enantiornthines.

>8) merged temporal openings.


 No argument here. 

>9) feathers.
 

Also seen in dinosaurs and to a small extent Longisuama (maybe.)


>Archeopteryx has only the last feature. One should expect to find the
>others to some extent (or at least the beginings of them) in ancestral
>birds.
 I have to disagree. Archaeopteryx has a lot of avian features.

 One important feature you didn't show is the double-condyled quadrate. 
It seems to be the one feature seen in birds that is not seen in 
dinosaurs ( of course this may be wrong, look at Troodon which appears 
to have a similiar quadrate.)
 Another important feature is the modified diapsid skull. This is where 
the supratemporal fenestrae and the infratemporal fenestrae merge.


 Despite my critisms I congratulate you on making a list like this. It 
is hard to make a list trying to diagnose the entire Aves. They just 
don't show a concrete seperation from dinosaurs.

 WMattTroutman


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