Titanosaurs have stupid cervicals

March 21, 2013

As I noted in a comment on the previous post, titanosaurs have stupid cervicals.

As evidence, here is as gallery of titanosaur cervicals featured previously on SV-POW!.

1. From Whassup with your segmented lamina, Uberabatitan ribeiroi?, an anterior cervical of that very animal, from Salgado and Carvalho (2008: fig. 5). As well as the titular segmented lamina, note the ridiculous ventral positioning of the cervical rib. It’s like it’s trying to be Apatosaurus, but it just doesn’t have the chops.

uberabatitan-cervicals-copy

2. From Mystery of the missing Malawisaurus vertebra, this alleged vertebra of that taxon from Jacobs et al. (1993:fig. 1), which completely fails to resemble all the other cervicals subsequently described from Malawisaurus (see the earlier post for details). Note the crazy sail-like neural spine and super-fat parapophyseal stump.

malawisaurus-1993

3. From Futalognkosaurus was one big-ass sauropod, this completely insane posterior cervical vertebra of Futalognkosaurus in right anterolateral view, with Juan Porfiri (175 cm) for scale. It’s super-tall — much taller than it is wide, and seemingly taller than it is long.

Posterior cervical vertebra of Futalognkosaurus in right anterolateral view; Juan Porfiri (175 cm) for scale

4. From Ch-ch-ch-changes, cervical 11 of Rapetosaurus, from Curry Rogers (2009:fig. 5). Notice how tiny the centrum is compared with the tall superstructure, and how the neural spine has such a distinct peak. Weird.

Rapetosaurus cervical

5. From Talking about sauropods on The Twenty-First Floor, cervical 9 of the same Rapetosaurus individual, from Curry Rogers (2009:fig. 9). The neural spine is a completely different shape from that of C11, but that is presumably mostly due to damage. One of the interesting things here is the apparent lack of pneumatic foramina in the centrum. They’re there somewhere: Curry Rogers (2009:1054) writes “In cervical vertebrae 9, 11, and 12, the centrum bears an elongate shallow pneumatic fossa with two anterior pneumatic foramina surrounded by sharp, lip-like boundaries.” But they are hard to make out! 

CurryRogers2009-rapetosaurus-fig9-C9

The meta-oddity here is that the cervicals of the four titanosaur genera pictures here are all so different from each other. What does this mean?

Probably only that Titanosauria is a huge, disparate, long-lived clade that encompasses far more morphological variation than (say) Diplodocidae. It’s a truism that we don’t, even now, really have a handle on titanosaur phylogeny — every new study that comes out seems to recover a dramatically different topology — so our perception of the clade is really as a big undifferentiated blob. In contrast, the division of Diplodocoidea into Rebbachisaurids, Dicraeosaurids and Diplodocids (plus some odds and ends) is nicely established and easy to think about.

So. Lots of work to be done on titanosaurs.

References

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2 Responses to “Titanosaurs have stupid cervicals”


  1. I think we have a fundamentally poor understanding of how sauropod cervical works, much less develop, and their relation to soft-tissue, that influences their morphology. Understanding the biomechanics of sauropod cervicals on more specific level than even relative orientation or posture would go a long way to resolving the value of relative characters for sauropod cervicals in phylogenetic analyses. Right now, it’s plug, plug, plug, without any sense of functional relationship or usefulness, merely how well a character fits to a given phylogeny.


  2. When people ask what titanosaurs differ from other sauroposd were like I usually quip that it’s like asking how anthropoids differ from other primates – there’s probably an answer, but you’re asking about a group that may be more diverse than everything else in the clade.


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