Re: Giant flightless birds

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

><<The purpose of my query is to gather data on groups of extinct 
>flightless birds to trace phylogeny to living forms and to the 
>dinosaurs. (Flightlessness being an ancestral trait and therefore a 
>semi-good marker for phylogenetic research, in my opinion. Of course, 
>I've said that before.) I'm trying to find out the adaptations of the 
>rest of the body in addition to/or because of the loss of flight. 
>Especially the pelvis.>>
>
><Well, let's talk about a flightless bird's pelvis. If alvarezosaurids 
>are birds, then they show a unique amount of variation in the structure 
>of the pelvis compared to other birds. Patagopteryx is 
>convergent on some ratites in the morphology of the pelvis (pubis and 
>ischium are of equal length and are nearly parallel, with a small 
>foot-like process on the dital end).>
>
>First I've heard that on *Patagopteryx*.

     Herculano and Bonaparte have described the pelvis of Patagopteryx 
as being basically similiar to the ratite pelvis ( pubis and ischium of 
equal length, both thin and rod-like, extending to the distal portion of 
the pygostyle).

><One of the strangest trends in flightless birds is the convergent 
>morphology of the pelvis. Some flightless ratites, anseriformes, 
>gruiformes, galliforms, podicipediformes, gaviiformes, and even 
>hesperornithiformes have a arrangements of the pelvis where the pubis 
>and ischium are nearly horizontal and extend to the distal end of the 
>pygostyle.>
>
>Ostriches have a pubic symphysis, if I'm not mistaken, while nearly all 
>other avian pelvises do not (e.g., passerines, strigiforms, penguins, 
>falconiforms). This may be a atavism, retroeval character, or something 
>else entirely, if true.

    Seperation of the distal pubes is a character of Hesperornis+ 
Icthyornis and all other birds. I'll have to check on whether Struthio 
has a pubis symphysis.

><The pelvis in phorusrhacids, however, is not in this arrangement, and 
>it resembles more of that of a flighted, volant bird. The arrangement 
is 
>conservative in all lineages of flightless birds (and I have only 
>scratched the surface on the diversity of them). It should be noted, 
>with *perhaps* the exception of Spenisciformes (penguins) and the 
>possiblilty of aquatic gaviiform ancestors, that most flightless birds 
>evolved in parallel of each other and they evolved the structure of 
>their pelvis convergently.>
>
>This brings me to something. I'm trying to get a hold of more info on 
>*Phorusrhacos*, especially something more than a restoration---skull, 
>arm, etc. Somewhere on the net, and article, a book....

    There's the _Discover_ article on phorusrhacids ( with a nice set of 
pictures of Andalgalornis ), a Paleoworld episode on them, a small 
section in Feduccia's book on them, Bob Chandler's SVP abstract, and 
this one:

 Chandler, R.M., 1994. The wing of Titanis walleri ( Aves: 
Phorusrhacidae ) from the late Blancan of Florida. _Bulletin Florida 
State Museum of Natural History, Biology Series 36 ( 6 ): 175-180.

  
>Jaime A. Headden
>
>PS: by the way, if you know, how many avian taxa have a notarium? 

   Most all have a notarium.

MattTroutman

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