Christine Argot of the MNHN, Paris, drew our attention to this wonderful old photo (from here, original caption reproduced below): [{.size-full .wp-image-9874 aria-describedby=“caption-attachment-9874” loading=“lazy” attachment-id=“9874” permalink=“http://svpow.com/2014/03/01/the-case-of-the-bandy-legged-diplodocus/1-7_diplodocus_2_l/” orig-file=“https://svpow.files.wordpress.com/2014/02/1-7_diplodocus_2_l.jpg” orig-size=“2362,1772”

Let’s take another look at that Giraffatitan cervical.

In his classic monograph, Hatcher (1901) illustrated the cervical vertebrae of the Diplodocus carnegii holotype CM 84 with beautiful drawings: {.aligncenter .size-full .wp-image-8014 loading=“lazy” attachment-id=“8014” permalink=“http://svpow.com/papers-by-sv-powsketeers/wedel-and-taylor-2013-on-sauropod-neural-spine-bifurcation/wedel-and-taylor-2013-bifurcation-figure-13-diplodocus-cervicals-from-hatcher/”

Last Tuesday Mike popped up in Gchat to ask me about sauropod neck masses.  We started throwing around some numbers, derived from volumetric estimates and some off-the-cuff guessing.

Here are cervical vertebrae 2-15 of Diplodocus carnegii in right lateral view, from Hatcher (1901: plate 3). Click to embiggen, and then just gaze in wonder for a while.

Earlier this month I was amazed to see the new paper by Cerda et al. (2012), “Extreme postcranial pneumaticity in sauropod dinosaurs from South America.” The title is dramatic, but the paper delivers the promised extremeness in spades.

Last time, we saw why Haplocanthosaurus couldn’t be a juvenile of Apatosaurus or Diplodocus , based on osteology alone.  But there’s more: Ontogenetic status of Haplocanthosaurus Here is where is gets really surreal.

Introduction Last time around, Matt walked through a lot of the detailed cervical morphology of Suuwassea and known diplodocids to show that, contra the suggestion of Woodruff and Fowler (2012), Suuwassea is distinct and can’t be explained away as an ontogenomorph of a previously known genus. Although Suuwassea is singled out for special treatment in this paper, other genera do not escape unscathed.

I don’t intend to write a comprehensive treatise on the morphology and phylogeny of Suuwassea . Jerry Harris has already done that, several times over (Harris 2006a, b, c, 2007, Whitlock and Harris 2010). Rather, I want to address the contention of Woodruff and Fowler (2012) that Suuwassea is a juvenile of a known diplodocid, building on the information presented in the first three posts in this series (Part 1, Part 2, Part 3).

In the previous post in this series I looked at the some of the easily available raw data on neural spine bifurcation in Morrison sauropods. In this post I’ll explain how serial variation–that is, variation along the vertebral column in one individual–is relevant to the inferences made in the new paper by Woodruff and Fowler (2012). But first, a digression, the relevance of which will quickly become clear.