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.

Western University of Health Sciences

Matt Wedel

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*Plateosaurus engelhardti* (originally *P. trossingensis*) SMNS 13200
cervical vertebrae 3-8 in left lateral view. C8 is roughly 15 cm long.
:::

In the [recent
post](http://svpow.com/2012/04/09/neural-spine-bifurcation-in-sauropods-part-2-why-serial-position-matters/)
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. Compared to posterior cervicals, anterior
> cervicals tend to have simpler pneumatic fossae and foramina, fewer
> laminae, and unsplit rather than bifid spines. In all of these things
> the anterior cervicals are similar to those of juveniles of the same
> taxa, and to those of adults of more basal taxa. This is also true in
> prosauropods--in *Plateosaurus*, the full complement of vertebral
> laminae is not present until about halfway down the neck.

I was working from memory there and actually understated things a bit.
*Plateosaurus* presacral vertebrae don't have well-developed spinal
laminae, but they do eventually get the four major diapophyseal
laminae--the anterior centrodiapophyseal lamina (ACDL), posterior
centrodiapophyseal lamina (PCDL), prezygodiapophyseal lamina (PRDL), and
postzygodiapophyseal lamina (PODL--please see the [lamina
tutorial](http://svpow.com/2007/11/10/tutorial-4-laminae/) if you need a
refresher on these and the other 15 commonly identified laminae). But
they aren't all present halfway down the neck--the ACDL doesn't really
show up until the cervicodorsal transition. The other three kick in
sequentially down the neck, as shown in the above image. I think that's
pretty cool, that you get different character states expressed at
different points along the neck, in one individual organism, at one
time. And possibly also at different times--in sauropods, the anterior
cervicals tend to look more 'juvenile' or 'primitive', even in adult
animals, so all of the cervicals go through a juvenile stage, but not
all of them grow out of it. I don't know if there's a word for
that--some kind of serial heterochronotopomorphy or the like--but
hopefully someone will enlighten me.

I took the original photo in the collections at the Staatliches Museum
für Naturkunde Stuttgart in the spring of 2004. Markus Moser and Rainer
Schoch were wonderful hosts during my visit. Mike did all the work of
turning the raw photo into a figure, so thanks to him for getting this
off my hard drive and out into the world.


<em>
 Plateosaurus engelhardti
</em>
(originally
<em>
 P. trossingensis
</em>
) SMNS 13200 cervical vertebrae 3-8 in left lateral view. C8 is roughly 15 cm long. In the recent post on serial variation in sauropod cervicals, I wrote:  I was working from memory there and actually understated things a bit.

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Serial changes in the vertebral laminae of Plateosaurus