Re: Long-necked stegosaur, head tail mimicry?

[Mike Taylor <mike@indexdata.com>]

Tim Williams writes:
 > Speaking of long sauropod necks... there's a new paper in the
 > pipeline on _Euhelopus_.  Although Wilson & Upchurch break up the
 > clade of long-necked Chinese sauropods ("Euhelopodidae", containing
 > _Euhelopus_, _Mamenchisaurus_, and _Omeisaurus_), they baulk at
 > erecting (or defining) a new Euhelopodidae, which would include
 > _Euhelopus_ and _Erketu_.

I should think so!  It would be disastrous to resurrect that name to
denote a completely different clade from the one that it has been
universally understood to mean.

By the way, note the (rather poor) phylogenetic definition of
Mamenchisauridae in Naish and Martill (2007:498) --

        Mamenchisauridae Young & Chao, 1972, a clade that we here
        diagnose as all those sauropods closer to Mamenchisaurus
        constructus Young, 1954 than to Saltasaurus loricatus
        Bonaparte & Powell, 1980 ...

I don't know, those University of Portsmouth guys.

 > Nevertheless, it's clear that *very* long necks evolved at least
 > twice in the Sauropoda - in the non-neosauropods (_Mamenchisaurus_,
 > _Omeisaurus_) and basal titanosauriforms (_Euhelopus_, _Erketu_).

At least FOUR times -- in Mamenchisauridae, Diplodocidae (the neck of
Supersaurus is best estimated at 15m, longer than any other),
Brachiosauridae sensu stricto and once or more within the huge,
ill-defined cloud that is Titanosauria.  This is covered briefly by
Matt Wedel's 2006 SVP abstract:
        
http://www.vertpaleo.org/publications/jvp/supplemental_data/26_3/SVP2006Abstracts.pdf
(page 103 of the PDF) and in much more detail in chapter four of his
2007 dissertation:
        http://sauroposeidon.net/Wedel2007-dissertation.pdf
(pages 200-263 of the PDF).  Irritatingly, this chapter is the only
one in the dissertation that has not yet been published.

 _/|_    ___________________________________________________________________
/o ) \/  Mike Taylor    <mike@indexdata.com>    http://www.miketaylor.org.uk
)_v__/\  "Clear use of function pointers is the heart of object-oriented
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