Re: correct this "definition"

[David Marjanovic <david.marjanovic@gmx.at>]

> > * Three or more vertebrae fixed to the hip bones
>
> In general, yes; but either reversed in a few Late Triassic forms or
> independantly evolved in Ornithischia, Sauropodomorpha, Theropoda.

This, in turn, depends on the definition of "sacral vertebra", as pointed 
out in Sereno's Historical Biology paper. "Fixed to the hip bones" doesn't 
begin to cover the observed variation.

> > * a hole rather than a socket in the hip for the leg bone
>
> Yes.

Not that it matters, but this is reversed in ankylosaurs and partially 
reversed in lots of birds.

> > but aren't the "ruling reptiles" the archosaurs?

Yes, except it's more like "ruling lizards".