My camera had a possibly-fatal accident in the field at the end of the day on Saturday, so I didn’t take any photos on Sunday or Monday. From here on out, you’re either getting my slides, or photos taken by other people.

Powell Museum sauropod humerus

On Sunday we were at the John Wesley Powell River History Museum in Green River, Utah, for the Cretaceous talks. There were some fossils on display downstairs, including mounted skeletons of Falcarius and one or two ornithischians,* and this sauropod humerus from the Cedar Mountain Formation (many thanks to Marc Jones for the photo).

* A ceratopsian and Animantarx, maybe? They were in the same room as the sauropod humerus, so it’s no surprise that I passed them by with barely a glance.

There were loads of great talks in the Cretaceous symposium on Sunday, and I learned a lot, about everything from clam shrimp biostratigraphy to ankylosaur phylogeny to Canadian sauropod trackways. But I can’t show you any slides from those talks, so the rest of this post is the abstact from Darren’s and my talk, illustrated by a few select slides.

Wedel Naish 2014 Sauroposeidon and kin - slide 1 title

Sauroposeidon is a giant titanosauriform from the Early Cretaceous of North America. The holotype is OMNH 53062, a series of four articulated cervical vertebrae from the Antlers Formation (Aptian-Albian) of Oklahoma. According to recent analyses, Paluxysaurus from the Twin Mountain Formation of Texas is the sister taxon of OMNH 53062 and may be a junior synonym of Sauroposeidon. Titanosauriform material from the Cloverly Formation of Wyoming may also pertain to Paluxysaurus/Sauroposeidon. The proposed synonymy is based on referred material of both taxa, however, so it is not as secure as it might be.

Wedel Naish 2014 Sauroposeidon and kin - slide 34 Sauroposeidon characters

Top row, vertebrae of Paluxysaurus. From left to right, the centrum lengths of the vertebrae are 72cm, 65cm, and 45cm. Main image, the largest and most complete vertebra of the holotype of Sauroposeidon. Labels call out features that are present in every Sauroposeidon vertebra where they can be assessed, but consistently absent in Paluxysaurus. Evaluating the proposed synonymy of Paluxysaurus and Sauroposeidon is left as an exercise for the reader.

MIWG.7306 is a cervical vertebra of a large titanosauriform from the Wessex Formation (Barremian) of the Isle of Wight. The specimen shares several derived characters with the holotype of Sauroposeidon: an elongate cervical centrum, expanded lateral pneumatic fossae, and large, plate-like posterior centroparapophyseal laminae. In all of these characters, the morphology of MIWG.7306 is intermediate between Brachiosaurus and Giraffatitan on one hand, and Sauroposeidon on the other. MIWG.7306 also shares several previously unreported features of its internal morphology with Sauroposeidon: reduced lateral chambers (“pleurocoels”), camellate internal structure, ‘inflated’ laminae filled with pneumatic chambers rather than solid bone, and a high Air Space Proportion (ASP). ASPs for Sauroposeidon, MIWG.7306, and other isolated vertebrae from the Wessex Formation are all between 0.74 and 0.89, meaning that air spaces occupied 74-89% of the volume of the vertebrae in life. The vertebrae of these animals were therefore lighter than those of brachiosaurids (ASPs between 0.65 and 0.75) and other sauropods (average ASPs less than 0.65).

Wedel Naish 2014 Sauroposeidon and kin - slide 64 Mannion phylogeny

Check this out: according to at least some versions of the Mannion et al. (2013) tree, Sauroposeidon and Paluxysaurus are part of a global radiation of andesaurids in the Early and middle Cretaceous. Cool!

Sauroposeidon and MIWG.7306 were originally referred to Brachiosauridae. However, most recent phylogenetic analyses find Sauroposeidon to be a basal somphospondyl, whether Paluxysaurus and the Cloverly material are included or not. Given the large number of characters it shares with Sauroposeidon, MIWG.7306 is probably a basal somphospondyl as well. But genuine brachiosaurids also persisted and possibly even radiated in the Early Cretaceous of North America; these include Abydosaurus, Cedarosaurus, Venenosaurus, and possibly an as-yet-undescribed Cloverly form. The vertebrae of Abydosaurus have conservative proportions and solid laminae and the bony floor of the centrum is relatively thick. In these characters, Abydosaurus is more similar to Brachiosaurus and Giraffatitan than to Sauroposeidon or MIWG.7306. So not all Early Cretaceous titanosauriforms were alike, and whatever selective pressures led Sauroposeidon and MIWG.7306 to evolve longer and lighter necks, they didn’t prevent Giraffatitan-like brachiosaurs such as Abydosaurus and Cedarosaurus from persisting well into the Cretaceous.

Wedel Naish 2014 Sauroposeidon and kin - slide 65 Cloverly sauropods

The evolutionary dynamics of sauropods in the North American mid-Mesozoic are still mysterious. In the Morrison Formation, sauropods as a whole are both diverse and abundant, but Camarasaurus and an efflorescence of diplodocoids account for most of that abundance and diversity, and titanosauriforms, represented by Brachiosaurus, are comparatively scarce. During the Early Cretaceous, North American titanosauriforms seem to have radiated, possibly to fill some of the ecospace vacated by the regional extinction of basal macronarians (Camarasaurus) and diplodocoids. However, despite a flood of new discoveries in the past two decades, sauropods still do not seem to have been particularly abundant in the Early Cretaceous of North America, in contrast to sauropod-dominated faunas of the Morrison and of other continents during the Early Cretaceous.

Wedel Naish 2014 Sauroposeidon and kin - slide 66 acknowledgments

That final slide deserves some explanation. On the way back from the field on Saturday–the night before my talk–a group of us stopped at a burger joint in Hanksville. Sharon McMullen got a kid’s meal, and it came in this bag. We took it as a good omen that Sauroposeidon was the first dinosaur listed in the quiz.

For the full program and abstracts from both days of talks, please download the field conference guidebook here.

Order up!

Sauroposeidon OMNH 53062 articulated right lateral composite with giraffe

Sauroposeidon is stitched together from orthographic views of the 3D photogrammetric models rendered in MeshLab. Greyed out bits of the vertebrae are actually missing–I used C8 to patch C7, C7 to patch C6, and so on forward. The cervical ribs as reconstructed here were all recovered and they are in collections, but they’re in several jackets and boxes and therefore not easily photographed.

The meter bars are both one meter as advertised. The giraffe neck is FMNH 34426 (from this post), which is actually 1.7 meters long, but I scaled it up to 2.4 meters to match that of the tallest known giraffe. I think it’s cool that a world-record giraffe neck is roughly as long as two vertebrae from the middle of the neck of Sauroposeidon.

There are loads of little morphological details in the Sauroposeidon vertebrae that are clearer now than they were in our old photographs, but those will be stories for other posts.

Sauroposeidon in 3D

April 18, 2014

Sauroposeidon meet Sauroposeidon

I was in Oklahoma and Texas last week, seeing Sauroposeidon, Paluxysaurus, Astrophocaudia, and Alamosaurus, at the Sam Noble Oklahoma Museum of Natural History, the Fort Worth Museum of Science and History, the Shuler Museum of Paleontology at SMU, and the Perot Museum of Nature and Science, respectively. I have a ton of interesting things from that trip that I could blog about, but unfortunately I have no time. Ten days from now, I’m off to Colorado and Utah for the Mid-Mesozoic conference and field trip, and between now and then I need to finish up my bits on three collaborative papers, get my summer anatomy lectures posted for internal peer review here at WesternU, and–oh yeah–actually write my conference talk. Fun times.

BUT after being subjected to the horror of the Yale Brontosaurus skull, I figured you all deserved a little awesome.

Photographing Sauroposeidon 2014-04-07

So here’s me getting one of 351 photos of the most posterior and largest of the Sauroposeidon jackets (this is not the awesome, BTW, just a stop along the way). This jacket holds what I once inferred to be the back half of C7 and all of C8. Now that Sauroposeidon may be a somphospondyl rather than a brachiosaur, who knows what verts these are–basal somphospondyls have up to 17 cervicals to brachiosaurids’ probable 13 (for a hypothetical view of an even-longer-necked Sauroposeidon, see this probably-prophetic post by Mike). The vertically-mounted skeleton in the background is Cotylorhynchus. Cotylorhynchus got a lot bigger than that–up to maybe 6 meters long and 2 or 3 tons–and was probably the largest land animal that had ever existed back in the Early Permian. Photo by OU grad student Andrew Thomas, whom you’ll be hearing about more here in the future.

I couldn’t crank the model myself on the road, thanks to the pathetic lack of processing power in my 6-year-old laptop (which will be replaced RSN). Andy Farke volunteered to do the photogrammetricizing with Agisoft Photoscan, if only I’d DropBox him the pictures. Here’s a screenshot from MeshLab showing the result:

Sauroposeidon lateral PLY 10 - 6 and 9 blended

And my best taken-from-overhead quasi-lateral photograph:

Sauroposeidon C8 jacket lateral photo 2014-04-07

If you’re curious, the meter stick at the top is actually one meter long, it just has the English measurement side showing. The giant caliper at the bottom is also marked off in inches, and it is open to 36.0 inches (it didn’t go to 1 meter, or I would have used that). You can tell that there is some perspective distortion involved here since 36 inches on the caliper is 1380 pixels, whereas the 39.4-inch meter stick is only 1341 pixels. Man, I hate scale bars. But they make good calibration targets.

Incidentally, after playing around with the model in orthographic mode in MeshLab, the distortions in the photos of the vertebrae themselves just scream at me. Finally, finally, I can escape the tyranny of perspective. Compare the ends of the big wooden beam at the top of the jacket to get a feel for how much the two views differ.

Working on Sauroposeidon again after all this time made me seriously nostalgic. I love that beast. I don’t think I’m exaggerating when I say that those vertebrae are the most gorgeous physical objects in the universe. Also, an appropriately huge thank-you to preparator Kyle Davies (of apatosaur-sculpting fame), collections manager Jen Larsen, and Andrew Thomas again for help with wrassling those verts around, and for sharing their thoughts and advice. Thanks also to curators Rich Cifelli and Nick Czaplewski for their hospitality and for the go-ahead to undertake this work, and to Andy Farke for generating the model.

I’ll have a lot more to say about this stuff in the future. I didn’t go to all this work just for giggles. For a long time I’ve had a hankering to do a paper on the detailed anatomy of Sauroposeidon, based on all of the things that I’ve noticed in the last decade that didn’t make it into any of the early papers. And now there’s the proposed synonymy of Paluxysaurus with Sauroposeidon. And “Angloposeidon” needs some attention–Darren and I have been thinking about writing “Angloposeidon II” for years now. And…well, plenty more.

So, loads more to come, but not for the next few weeks. Eventually I’ll be publishing all of this–the photos, the 3D models, the whole works. Stay tuned.

UPDATE a few days later

Man, I am frazzled, because I forgot to include the moral of the story: if I can do this, you can do this. There are good, free photogrammetry programs out there–Peter Falkingham published a  whole paper on free photogrammetry in 2012, and posted a guide to an even better program, VisualSFM, on Academia.edu. Even Agisoft Photoscan is not prohibitively expensive–under $200 for an educational license. MeshLab is free and has hordes of good free tutorials. For the photography itself, you basically just build a virtual dome of photos around an object. If you need more instructions than that, Heinrich has written a whole series of tutorials. It doesn’t take a fancy camera–I used a point-and-shoot for the Sauroposeidon work shown here (a Canon S100 operating at 6 megapixels, if anyone is curious). What are you waiting for?

Illustration talk slide 47

Illustration talk slide 48

Illustration talk slide 49

Illustration talk slide 50

That last one really hurts. Here’s the original image, which should have gone in the paper with the interpretive trace next to it rather than on top of it:

Sauroposeidon C6-C7 scout

The rest of the series.

Papers referenced in these slides:

Illustration talk slide 44

Illustration talk slide 45

Illustration talk slide 46

On that last slide, I also talked about two further elaborations: figures that take up the entire page, with the caption on a separate (usually facing) page, and side title figures, which are wider than tall and get turned on their sides to better use the space on the page.

Also, if I was doing this over I’d amend the statement on the last slide with, “but it doesn’t hurt you at all to be cognizant of these things, partly because they’re easy, and partly because your paper may end up at an outlet you didn’t anticipate when you wrote it.”

And I just noticed that the first slide in this group has the word ‘without’ duplicated. Jeez, what a maroon. I’ll try to remember to fix that before I post the whole slide set at the end of this exercise.

A final point: because I am picking illustrations from my whole career to illustrate these various points, almost all fail in some obvious way. The photos from the second slide should be in color, for example. When I actually gave this talk, I passed out reprints of several of my papers and said, “I am certain that every single figure I have ever made could be improved. So as you look through these papers, be thinking about how each one could be made better.”

Previous posts in this series.

References

Illustration talk slide 39

Illustration talk slide 40

Illustration talk slide 41

Illustration talk slide 42

Illustration talk slide 43

The Sauroposeidon stuff is cribbed from this post. For the pros and cons of scale bars in figures, see the comment thread after this post. MYDD is, of course, a thing now.

Previous posts in this series.

Reference:

Wedel, M.J., and Taylor, M.P. 2013. Neural spine bifurcation in sauropod dinosaurs of the Morrison Formation: ontogenetic and phylogenetic implications. Palarch’s Journal of Vertebrate Palaeontology 10(1): 1-34. ISSN 1567-2158.

Sauroposeidon and friends

February 24, 2014

Sauroposeidon and kin cervicals - DRAFTAs a break from photography posts, here are four pretty big vertebrae that swirl in the same thought-space in my head. All are shown to scale, in right lateral view. These are not the biggest sauropod cervical vertebrae–Supersaurus beats them all, and there are vertebrae of Puertasaurus, Alamosaurus, and Futalognkosaurus that rival the big Sauroposeidon vert, but those are either less well preserved or still awaiting detailed description.

Incidentally, I think BYU 12867 is a C10. The centrum proportions are about right, compared to Giraffatitan, and the neural spine looks good, too, like a geometric transformation of the big Giraffatitan C8. Also, the drawn-in prezyg outline for MIWG.7306 is a little short; the actual prezyg is a monster and would have overhung the condyle by another 10cm or so. I’m pretty sure that we had a composite photograph showing this at one point, but irritatingly none of us can find it at the moment. If it turns up, I’ll update the image.

For a long time I thought Sauroposeidon was a brachiosaurid. Now it seems to be a somphospondyl (D’Emic 2012) or possibly even a basal titanosaur (Mannion et al. 2013), even if we stick just to the holotype. But if it’s not a brachiosaurid, it’s cervical vertebrae are at least coarsely brachiosaur-y in outline.

You  may recall from Naish et al. (2004) that MIWG.7306 shares several derived characters with the holotype vertebrae of Sauroposeidon. Does that mean that Angloposeidon is a somphospondyl or titanosaur as well? I dunno–as always, we need more material–but it’s an interesting possibility.

References

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