RE: Titanosaurs and their relationship to Brachiosaurs and Diplodocoids.

[mike@miketaylor.org.uk (Mike Taylor)]

Michael Mortimer writes:
>> Aside from the absence of a ungual claw (which I read was reduced
>> in Brachiosaurids) I haven't read of anything that connects
>> Titanosaurs and Brachiosaurids (but I acknowledge that this is
>> probably due to poor sources).
> 
> Here's Wilson's (2002) list of macronarian and titanosauriform
> characters-
> 1. External naris, maximum diameter greater than orbital maximum diameter.
> 2. Coronoid process on lower jaw (surangular depth more than twice depth of 
> the angular).
> 3. Surangular ridge separating adductor and articular fossae.
> 4. Dentary teeth 17 or fewer.
> 5. Posterior dorsal centra opisthocoelous.
> 6. Longest metacarpal-to-radius ratio 0.45 or more.
> 7. Metacarpal I longer than metacarpal IV.
> 8. Puboischial contact one-half total length of pubis.
> 1. Spongy presacral bone texture.
> 2. Mid-cervical centra elongate, length four times posterior centrum height.
> 3. Dorsal ribs with pneumatic cavities.
> 4. Anterior dorsal ribs plank-like.
> 5. Metacarpal I distal condyle undivided, phalangeal articular surface 
> reduced.
> 6. Metacarpal I distal condyle oriented perpendicular to axis of shaft.
> 7. Iliac preacetabular process semicircular.
> 8. Femoral shaft with lateral bulge, proximal one-third deflected medially.

(To clarify for anyone who's not familiar with these groups: the first
set of eight characters that Mickey listed here are those that unite
_Camarasaurus_ with the brachiosaur-titanosaur clade; only the second
set of eight unite titanosaurs with brachiosaurs.)

I only recently discovered that Wilson's 2002 analysis is freely
available (along with the rest of his publications) at:
        http://www-personal.umich.edu/~wilsonja/JAW/Publications.html

I _highly_ recommend this for anyone who's interested in sauropods.
Although Upchurch et al.'s (2004) analysis is nominally two years more
recent, its publication date is only as late as it is because of the
looong delays in the publication of _The Dinosauria_ 2nd ed., so that
in many respects Wilson (2002) is still the most up to date sauropod
analysis.  It also contains a very helpful discussion of earlier
analyses and where they were in error.

Also available to download from the same page is Wilson and Sereno's
1998 sauropod analysis.  Although its conclusions are now superseded
by Wilson 2002, it is well worth reading for its exceptionally clear,
detailed and well illustrated descriptions of the characters that are
used.

 _/|_    ___________________________________________________________________
/o ) \/  Mike Taylor  <mike@miketaylor.org.uk>  http://www.miketaylor.org.uk
)_v__/\  "You get facts from non fiction, truth from fiction" --
         David Shaw.