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

Re: Yonghesuchus, was Shuvosaurus

Earlier I wrote:

The Proterochampsidae lies outside of whatever is left of the
Archosauriformes. You'll find they nest in a continuum from Youngina -
Choristodera - Proterochampsidae - Doswellia  - Parasuchia.

D. Marjanovic wrote:

That's a very strange assemblage. 

>>>> Strange only because it hasn't been TRIED before. Lay them out on paper. 
>>>> It'll make sense.

DM: Are you sure you've included all proposed
apomorphies of Archosauriformes as characters in your analysis? 

>>>>> Not necessary, as explained way earlier. Taxon inclusion is all that is 
>>>>> necessary after 150 or so characters are used. If you're worried about it 
>>>>> though, suggest a character or ten that would attract other (traditional) 
>>>>> taxa. Would love to see the list. You can choose to keep it private if 
>>>>> you wish and I'll respect your request.

DM: Perhaps -- perhaps -- worse yet: if you don't find Lepidosauromorpha and 
Archosauromorpha as sistergroups to the exclusion of *Youngina*, then you need 
to postulate that the "diapsid" middle ear evolved twice. 

>>>>> In the Diapsida, if is difficult to find any characters that occur in 
>>>>> isolation. The homoplasy index is way higher than I've ever seen 
>>>>> elsewhere. Although the "diapsid" middle ear is not visible in the great 
>>>>> majority of taxa â?? and so did not make my character list â?? if it 
>>>>> evolved twice or more then it would join the great majority of characters 
>>>>> that also pop up repeatedly. 

And if you have good material on Youngina, please point the way~!  This is a 
taxon that needs more study. Broom's illustrations are not up to modern par. 

David Peters
St. Louis