The problem with Puertasaurus

Puertasaurus reuili

Puertasaurus reuili

When I released my Thunder Lizards  size comparison I was asked why a few of the largest animals were rendered in gray, and when I would be making the actual skeletal available. Using gray silhouettes solved an aesthetic concern (the image was threatening to get too busy), but it turns out that those critters have another problem: they are not known from very incomplete remains.

So here is the skeletal of Puertasaurus in all its "glory". I have a fully restored version as well, but it's not going to be making a public appearance, as frankly I don't want it to be separated from the rigorous version, as that could give off the impression that the animal is better known. In fact even this version is somewhat misleading, as the two tail vertebrae were reported but not figured or described - I don't actually know how big they were!

That's not to say the reconstruction is a fantasy - it's status as a lognkosaur seems secure, and we have very good remains of some of its relatives. And the neck and back vertebrae actually provide a pretty reasonable basis for scaling the largest parts of Puertasaurus. That said, I feel it's important for scientists (and scientific illustrators) not to inadvertently mislead people about the level of inference involved.

So enjoy the skeletal, but please do so responsibly! 

The biggest of the big

Thunder Lizards 4 blog.jpg

I don't know if that grabs your attention, but sorting out the size of giant sauropods sure grabs mine. Let's take a more detailed look at some of the critters in this image:

First off, I need to admit that this is not all inclusive. The legendary Amphicoelias fragillimus will never be included (unless more material is found). I have not sufficiently nailed down the scaling of Argentinosaurus yet to include it, but early scaling makes it look like it's the same size or slightly smaller than Puertasaurus (which I did include).

Note that most of these animals are only known from a single specimen (and often quite incomplete skeletons at that), which means that we don't really know what the size range of animals was in a living population. So keep in mind that while we can compare individual specimens, we can't say with any certainty that the biggest skeleton really came from the biggest sauropod species.

Here are some other quick hits:

1) For personal reasons I love me some Supersaurus. I've scaled the reconstruction to the size of the WDC specimen (32m), though the type specimen may have reached 34m in length. Either way it's the longest sauropod we can reasonably restore, though it certainly was not the heaviest (diplodocids tend to be fairly slab-sided compared to titanosaurs).

2) The large NMMNH Diplodocus specimen (originally named Seismosaurus) is also very long (~30m) but probably even lighter in mass.

3) Diplodocids may rule the roost in length, but macronarians seems to (mostly) crush them in terms of mass. Puertasaurus is currently my reigning champion; filling in the (extensive) missing elements with other lognkosaur relatives leads to a 27 meter long animal that is clearly the heaviest of the group (I'll speculate maybe in the 60-70 tonne range, but treat that as arm waving until it's verified by volumetric or double integration analysis).

4) To elaborate on preliminary Argentinosaurus results (not included above), it’s in the same size range as Puertasaurus, but basal titanosaurs may have had somewhat shorter tails (hence the smaller length) and the vertebrae aren't quite as wide as Puertasaurus, so my best guesstimate is that it loses on both accounts to it's lognkosaur relative, if only by a weeeee bit.

5) I didn't include Paralititan but I did scale it (hey, there's only so much space). It's large, but appears to be somewhat smaller than the Dallas specimen of Alamosaurus.

6) Speaking of Alamosaurus, I spent a lot of time trying to sort out who had the biggest fragmentary remains between Fowler & Sullivan (2010) and Guzman-Gutierrez & Palomino-Sanchez (2006). The tibia from Mexico is easily biggest (see gray silhouette behind the main Alamosaurus), but foreground skeletal here is based on Fowler and Sullivan's largest specimen (an isolated tail vertebrae) which happens to be from animal almost exactly the same size as the specimen on display at the Perot Museum of Nature and Science. Of course at this point we don't know for sure if the mexican tibia is truly Alamosaurus, or something new.

6) Brachiosaurus has long been abandoned in discussions of who is the largest dinosaur, but I'm not sure that's a good idea. The skeletal above is restored to the size of the type specimen, but some of the Utah specimens may be larger. The very broad-gutted Puertasaurus ekes out a larger size, but with such small sample sizes I don't think Brachiosaurus can actually be ruled out at the species level.

7) On the other hand, the significantly less robust Giraffatitan probably can be ruled out despite being quite tall.

8) While titanosaurs are generally heavier than diplodocids, very large Apatosaurus specimens appear to fit comfortably in the same size class. In addition to the Oklahoma specimen I have seen a few other (unpublished) apatosaur specimens that at least rival it in size.

So there you have it. If you have any other questions hit me up in the comments section below.

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Check out the Walking with Dinosaurs movie trailer, with "my" dinosaurs

I know, it's not exactly an earth-shaking post on anatomy or reconstructing prehistoric life, but as I mop up some of the duties that have taken me away from blogging the last few months I thought I'd share this trailer, which shows off some of what took time away from blogging last year at this time:

I know that some will object to the anthropomorphization of the dinosaurs' actions, but actually a ton of time was spent on trying to develop less mammalian behaviors and expressions that would still read to an audience. In the end not all of them worked out, but the realities of such a project are that no movies with this sort of budget will get made if they people fronting the cash think audiences won't be able to relate to it.

I think the anatomy will be some of the best ever seen on the silver screen. The compositing and color in one or two of the shots don't look as good as say the Jurassic Park movies, but with a final release not coming until holidays in 2013 I seriously doubt the entire film has been through final color grading, so I wouldn't let that bother you.

What do you guys think?

P.S. I was only one of the anatomy designers - Mark Witton was the other major designer that I know of (that is, created anatomical creature design illustrations as well as consulted), although there was an impressive assortment other paleontologists consulting on the project. After the 2D design was done the talented David Krentz added greatly to the character designs while transferring our work into the realm of three dimensions.

Even after models are made a project like this depends on an army of incredibly talented artists, including those who paint the models, the technical directors and riggers who make it so those static models can move, and the animators who bring them to life. The finished look also strongly depends on the texture and render artists, including shader development, digital lighting, and the people who composite and color grade the finished imagery. I only use the term "my" to illustrate enthusiasm for having played a role, not to imply that the role was more than a cog in a large and very talented army of people who worked on the project.

Massive changes incoming to diplodocid sauropod stance

apatosaurus+louisae+updated+April+2013.jpg

I know it's been a while since I posted anything, and luckily I have a backlog of content to share in the coming weeks, but I'm so excited about this project that I felt I had to post this, if for no other reason than as a warning to artists out there that are thinking about restoring sauropods in the near future. In particular diplodocoids - think "therizinosaur" and you'll be on the right track. I can't say too much until the paper clears embargo later this week, but all of the oddities we see in diplodocoids will make a lot more sense, including the massive upcurve in the tail. It also nicely links Taylor et al's work on neck posture with Emily Giffin's older work on reduced forelimb innervation in Apatosaurus.

More as soon as the journal will allow it!

Edit: Well it's April 2nd, and I'm going to have a post on this prank up in the next day or two, but in case you are landing on this page from an external source I wanted to clarify that it was indeed an April Fool's prank.

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