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Re: titanosaurs

Rutger Jansma (fam.jansma@worldonline.nl) wrote:

<How much is actually known for Opisthocoelicaudia?>

  The entire post-cervical postcrania with the following exceptions:

  Eight articulated presacral dorsals, with three articulated but
disassociated anterior dorsals, the most cranial of which shows some
cervical anatomy that makes me thinks it what is very rare in sauropods: a
cervicodorsal. All ribs. The sacrum is complete but the last sacral arch
and the left side are damaged. 34 sequential caudals are preserved
including the most anterior vertebrae, and the end of the series was
probably only a few more elements long, so hypothetically at or just less
than 40. The shoulder and sterna are complete, and so is the left
forelimb, but the right has only three metacarpals (the left has a
complete arch), and the left pes has only three metatarsals without a
right pes. The pelvis is partially eroded, but every part of each bone is
reserved: lacking proximal right pubis and distal left, the anterior left
and posterior right ilia, and the dorsal margin of both were damaged
preburial. Otherwise, everything is there. Interestingly, the pelves are
fused into innominate elements, and one astragalus is fused to its tibia
wheras the other is not.

  Other info, for your info:

  specimen, ZPAL MgD-I/48; femoral and hindlimb lengths relatively 1395 mm
and 2.47m; caudal series 4.5m (but with some distance between caused by
the espansion of the articular surfaces and cartilage with meniscae making
the know length about 5m), estimated total vertebral column length (sacrum
is roughly 1m, estimated with eroded bit of last sacral) 7.895m, and with
additional meniscae and cartilages, 8.59m. Other vertebral estimates from
gross centrum length excepting the articular balls. The specimen is from
Altan Ula IV, a Nemegetskaya svita locality, and the same site from which
*Avimimus* and *Udanoceratops* hail from, but since the latter two have
been conceived as being Djadokhtan in age by some (recent Ukhaa Tolgod
analyses) and Baruungoyotian by others (as in Encyclopedia of Dinosaurs,
Currie and Padian, under the heading "Barun Goyot Formation"), it seems
this is shaky stuff.


  Incidentally, if *Opisthocoelicaudia* is being suggested as a
euhelopodid or of such descent, one might want to put forth corroborative
evidence rather than just draw parallels given bifidy and caudal opsithocoely.

Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

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