Dinogeorge@aol.com wrote:
"This was secondarily and independently acquired, since basal segnosaur Alxasaurus emphatically does not have the semilunate carpal."
It most emphatically does. From the paper describing _Alxasaurus_: "The first distal carpal possess a doubly keeled proximal articular surface ("pully")..." (p.2114, Russell and Dong, 1993). The section on the Therizinosauroidea in The Dinosauria, 2nd Edition also describes the semilunate carpal joint of _Alxasaurus_: "...well-developed trochlear surface with two ridges" (p.156, lark et al., 2004).
> "Inflated basiphenoid" is a segnosaur autapomorphy, not a segnosaur-bullatosaur
> symplesiomorphy.
This is irrelevant to the issue of prosauropod affinities.
> And here we have the perennial problem of cladistics: a host of evolutionarily labile junk
> characters can overwhelm an important character and completely subvert an analysis. And
> there's no way to tell, so we live in the fool's paradise that cladistic analysis invents.
Says you. But I'd love to know your special insight that allows you to discriminate between "important" and "junk" characters. People sometimes fall into the trap of assuming that the most "important" characters are those that they are most familiar with and/or happen to support their pet theories. The corollary is that the "junk" characters are those that are most inconvenient to their pet theories. Hmmm...
Cheers
Dr Tim Williams
Dinogeorge@aol.com wrote:
In a message dated 7/26/2005 3:59:15 PM Pacific Standard Time, tijawi@yahoo.com writes:
The furcula is just one character.
And here we have the perennial problem of cladistics: a host of evolutionarily labile junk characters can overwhelm an important character and completely subvert an analysis. And there's no way to tell, so we live in the fool's paradise that cladistic analysis invents.
Hey, crurotarsal ankle is just one character. So why isn't Dave Peters's cladogram with Lotosaurus as sister group of Ornithischia correct? He found lots of ornithischian characters in Lotosaurus.
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