In the recent post on serial variation in sauropod cervicals, I wrote: Even in ‘adult’ sauropods like the big mounted Apatosaurus and Diplodocus skeletons, the anterior cervicals are less complex than the posterior ones.

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).

This is the third post in a series on neural spine bifurcation in sauropods, inspired by Woodruff and Fowler (2012). In the first post, I looked at neural spine bifurcation in Morrison sauropod genera based on the classic monographic descriptions. In the second post, I showed that size is an unreliable criterion for assessing age and that serial variation can mimic ontogenetic change in sauropod cervicals.

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.

The discussion over the new paper by Woodruff and Fowler (2012)–see this post and the unusually energetic comment thread that follows–made me want to go back to the literature and see what was known or could be inferred about neural spine bifurcation in the Morrison sauropods before the recent paper was published.

By one of those happy coincidences that you sometimes get, today saw the publication of not one but two dinosaur ontogeny papers: this morning I was sent a copy of Woodruff and Fowler (2012) on ontogenetic changes in the bifid spines of diplodocoids, and tonight I was alerted to Werning (2012) on Tenontosaurus growth trajectories based on osteohistology. It’s interesting to compare them.

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Sorry to have written so much about publishing politics recently, and so little about sauropod vertebrae!  That stuff is important, and I give you fair warning I will be returning to it soon.

Although I’m on record of being no fan of the tabloids, there’s no doubt that they are hugely influential.  So it has to be good news to find that in the last few hours, both Nature and Science have publicly come out against the Research Works Act.