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RE: Family Nemegtosauridae
Try to imagine sauropod phylogeny with neural-spine bifurcation as
>just once<, but in several stages, starting with the anterior dorsals
posterior cervicals, and then progressing up the neck and down the back.
I find that rather difficult to swallow. It might make the evolution of one
character straight forward but it introduces a whole buttload (is this term
official jargon now? ;-) of other convergences and/or reversals. I think
that the bifid-spined Mamenchisaurus is still better placed with the
strikingly similar but single-spined Omeisaurus,ditto for Diplodocidae +
Dicraeosauridae and Rebbachisauridae, Camarasaurus and Titanosauriforms
(includes Brachiosauridae) and Phuwiangosaurus and Titanosauria.