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Re: What is Saltopus?



In a message dated 9/4/00 5:50:06 PM EST, mickey_mortimer@email.msn.com 
writes:

<< George Olshevsky wrote-
 
 > How is this a synapomorphy of Ornithodira when any >flying< bird blows
 this
 > 50% ratio away?
 
 The same way it can be a synapomorphy if sauropods, stegosaurs, ankylosaurs,
 etc. all have higher than a 50% ratio.  It's most parsimonious to think it
 reversed several times, but is still usefull for determining relationships
 among basal members. >>

In BCF, the forelimb to hindlimb ratio is close to 1 plesiomorphically for 
Archosauria, and it becomes smaller convergently within various lineages. It 
remains close to 1 throughout the lineage that leads to birds, even 
increasing beyond 1 as forelimbs develop into wings. Same with pterosaur 
lineage, if that is considered an ornithodiran group. Ratite birds typically 
have a small forelimb to hindlimb ratio, but I don't think anyone would argue 
(although I believe Percy Lowe might have, in the 1930s) that this feature is 
synapomorphic with the small forelimb to hindlimb ratios seen in various 
theropod lineages. There is, therefore, also no good reason to argue that the 
small forelimb to hindlimb ratios of the various theropod lineages are 
synapomorphic with one another.