Re: paleonet Origin of birds

[Thomas Yancey <yancey@xxxxxxxxxxxx>]

Everyone seems to agree on the matter of relationship, but this 
question needs a little more explanation for the non-specialist and 
especially for students without any background. People who teach will 
be faced with answering similar questions from students and a summary 
of basics would be appreciated.

If birds have a saurischian hipped skeletal structure, is the 'bird 
hipped' skeletal structure of the onithischians a case of bad naming, 
or has the hip structure of the saurischians changed significantly 
over the course of evolution?
If it is a case of bad naming, what was the reason for the poor 
choice of terms?

Note that this question does not relate to determining relationship, 
it relates to understanding the appropriateness of names and the 
reason for the confusing names that have been used in discussing the 
hip structure of group names of dinosaurs and birds. A short answer 
to this type of question will quickly satisfy students and will make 
learning more than simple memorization of terms.

  T. Yancey




>You've got it essentially correct. Birds are descendants of small 
>theropods making them dinosaurs themselves. Theropods are 
>saurischians but the "lizard hipness" of the entire group was not 
>meant to imply relatedness, just similarity. The very birdlike 
>non-bird theropods weren't well known at the time of the origin of 
>the word saurischian and, as it turns out, their hips are more 
>birdlike than the ornithischians.
>
>-Carl
>
>At 09:58 AM 4/11/2005, you wrote:
>>If I understand it correctly, birds are thought to be closely 
>>related (derived from or cousins with) the small theropod 
>>dinosaurs.  But theropods are part of sauriscia, the "lizard 
>>hipped" clad.  Are ave hips really like ornithicia ?  Is there a 
>>disconnect here, or are my understanding of dinosaur clads 
>>incorrect.
>>
>>(Forgive my spelling)
>>
>>Am I being to simple minded here ?
>>
>>
>>Al McCarrick
>
>Carl Mehling
>Fossil Amphibian, Reptile, and Bird Collections
>Division of Paleontology
>American Museum of Natural History
>Central Park West @79th Street
>New York, NY  10024
>(212) 769-5849
>Fax: (212) 769-5842
>cosm@amnh.org