John Yasmer, DO (right) and me getting ready to scan MWC 8239, a caudal vertebra of Diplodocus on loan from Dinosaur Journey, at Hemet Valley Imaging yesterday.

Alignment lasers – it’s always fun watching them flow over the bone as a specimen slides through the tube (for alignment purposes, obviously, not scanning – nobody’s in the room for that).

Lateral scout. I wonder, who will be the first to correctly identify the genus and species of the two stinkin’ mammals trailing the Diplo caudal?

A model we generated at the imaging center. This is just a cell phone photo of a single window on a big monitor. The actual model is much better, but I am in a brief temporal lacuna where I can’t screenshot it.

What am I doing with this thing? All will be revealed soon.

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Preserved bits of the Snowmass Haplocanthosaurus, MWC 8028, with me for scale. Modified from Wedel (2009: fig. 10), but not much – MWC 8028 was about the same size as CM 879.

Let’s say you had a critter with weird neural canals and super-deeply-dished-in centrum-ends, and you wanted to digitally rearticulate the vertebrae and reconstruct the spinal cord and intervertebral cartilages, in a project that would bring together a bunch of arcane stuff that you’d been noodling about for years. Your process might include an imposing number of steps, and help from a LOT of people along the way:

1. Drive to Dinosaur Journey in Fruita, Colorado, to pick up the fossils and bring them back to SoCal. (Thank you Paige Wiren, John Foster, and Rebecca Hunt-Foster for an excuse to come to the Moab area, thank you Brian Engh for the awesome road trip, and thank you Julia McHugh for access to specimens and help packing them up!).

2. Take the fossils to the Hemet Valley Medical Center for CT scanning. (Thank you John Yasmer and team.)

3. Find a colleague who would help you generate 3D models from the CT scans. (Thank you Thierra Nalley.)

4. Talk it over with your university’s 3D vizualization team, who suggest a cunning plan: (Thank you Gary Wisser, Jeff Macalino, and Sunami Chun at WesternU.)

5. They print the best-preserved vertebra at 75% scale. (50% scale resin print shown here.)

6. You and a collaborator physically sculpt in the missing bits with some Super Sculpey. (Thank you Jessie Atterholt for sculpting, and thank you Jeremiah Scott for documenting the process.)

(7.) The 3D-viz team use their fancy optical scanner (basically a photogrammetry machine) to make:

  • a second-generation digital model (digital)
  • from the sculpted-over 3D print (physical)
  • of the first-generation digital model (digital)
  • made from the CT scans (digital)
  • of the original fossil material (physical).

(8.) With some copying, pasting, and retro-deforming, use that model of the restored vert as a template for restoring the rest of the vertebrae, stretching, mirroring, and otherwise hole-filling as needed. (Prelim 2D hand-drawn version of caudal 1 shown here.)

(9.) Test-articulate the restored vertebrae to see if and how they fit, and revise the models as necessary. (Low-fi speculative 2D version from January shown here.)

(10.) Once the model vertebrae are digitally rearticulated, model the negative spaces between the centra and inside the neural canals to reconstruct the intervertebral cartilages and spinal cord.

(11.) Push the university’s 3D printers to the limit attempting to fabricate an articulated vertebral series complete with cartilages and cord in different colors and possibly different materials, thereby making a third-generation physical object that embodies the original idea you had back in January.

(12.) Report your findings, publish the CT scans and 3D models (original and restored), let the world replicate or repudiate your results. And maaaybe: be mildly astonished if people care about the weird butt of the most-roadkilled specimen of the small obscure sauropod that has somehow become your regular dance partner.

We did number 6 yesterday, so just counting the arbitrarily-numbered steps (and ignoring the fact that 7-12 get progressively more complicated and time-consuming), we’re halfway done. Yay! I’ll keep you posted on how it goes from here.

It’s been a bit since my last update. That’s how things go on the road. We got in some time for exploration and a little prospecting.

We also had to close the quarry. Anne Weil, whose dig London and I were out there to assist on, brought a speaker on the last day and played us out with a hydration song while we shut everything down for another year. We found some great stuff, and I’m anxious for you to get to see it, but there’s work to do first. Rest assured, I’ll keep you posted when the time comes.

The extant wildlife continued to be a source of enjoyment and inspiration, especially this cottontail. Rabbits, baby!

Time goes on, and so does the road. My road leads back home, and then back out again. I’ll check in when I can. Hope your summer is half as fun.

Afield in Oklahoma

June 25, 2018

Clouds over Black Mesa.

Baby spadefoot toad, with my index finger for scale.

Someone was here before us. Even though Black Mesa is best known for its Morrison exposures and giant Jurassic dinosaurs, there are Triassic rocks here, too, which have produced both body fossils and tracks, including these.

Seen but not photographed today:

  • a group of pronghorn by the side of the road, with two babies;
  • a deer that ran across the road right in front of our vehicle;
  • a wild turkey foraging in the ditch next to the road;
  • a few jackrabbits, and more cottontails than you can shake a stick at;
  • loads of prairie dogs.

Now if you’ll excuse me, I have to go watch a thunderstorm.

Remember this broken Giraffatitan dorsal vertebra, which Janensch figured in 1950?

It is not only cracked in half, anteroposteriorly, it’s also unfused.

Here’s a better view of the broken face, more clearly showing that the neural canal is (a) much taller than wide – unlike all vertebrate spinal cords – and (b) almost entirely situated ventral to the neurocentral joint, getting close to the condition in the perverted Camarasaurus figured by Marsh.

Here’s a dorsal view, anterior to the top, with Mike’s distal forelimbs for scale.

Left lateral view.

Right lateral view – note the subtle asymmetries in the pneumatic foramen/camera. A little of that might be taphonomic distortion but I think much of it is real (and expected, most pneumatic systems produce asymmetries).

And postero-dorsal view, really showing the weird neural canal to good advantage. In this photo and in the pure dorsal view, you can see that the two platforms for the “neural arch” – which, as in the aforementioned Camarasaurus, is neither neural nor an arch – converge so closely as to leave only a paper-thin gap.

A few points arise. As explained in this post, it makes more sense to talk about the neurocentral joint migrating up or down relative to the neural canal, which is right where it always is, just dorsal to the articular faces of the centrum.

So far, in verts I’ve seen with “offset” neurocentral joints, the joint tends to migrate dorsally in dorsal vertebrae, putting the canal inside the developmental domain of the centrum (which now includes a partial or total arch in an architectural sense, even though the chunk of bone we normally call the neural arch develops as a separate bit) – as shown in the first post in this series. In sacral and caudal vertebrae, the situation is usually reversed, with the joint shifted down into what would normally be the centrum, and the canal then mostly or completely surrounded by the arch – as shown in the second post in the series. This post then doesn’t really add any new concepts, just a new example.

Crucially, we can only study this in the vertebrae of juveniles and subadults, because once the neurocentral joints are fused and remodeled, we usually can’t tell where the old joint surface was. So it’s like cervicodorsal and caudal dorsal pneumatic hiatuses, in that the feature of interest only exists for part of the ontogeny of the animal, and our sample size is therefore inherently limited. Not necessarily limited by material – most museums I’ve visited have a fair amount of juvenile and subadult material in the collections – but limited in published visibility, in that for many sauropods only the largest and most complete specimens have been monographically described.

So once again, the answer is simply to visit collections, look at lots of fossils, and stay alert for weird stuff – happily, a route that is open to everyone with a legitimate research interest.

Reference

  • Janensch, W. 1950. Die Wirbelsaule von Brachiosaurus brancai. Palaeontographica (Suppl. 7) 3:27-93.

Last Wednesday, May 9, Brian Engh and I bombed out to Utah for a few days of paleo adventures. Here are some highlights from our trip.

We started at a Triassic tracksite on Thursday. But I’m not going to post any pictures of the tracks – those will be coming to a Brian Engh joint near you in the future. Instead, I’m going to talk about this little male collared lizard whose territory included the tracksite. He was fearless – didn’t want to run off and leave us yahoos wandering around his patch of desert unsupervised. Brian tickled his chin at one point.

Getting this close to him is how I got shots like this one:

Click through to the big version, it’s worth it.

One more shot of a couple of cool desert dwellers. I was so fixated on the lizard that I didn’t realize until later that Brian was in the frame, taking a much-needed hydration break.

On Friday we had a temporary breaking of the fellowship. I went to Fruita, Colorado, to visit the Dinosaur Journey museum. You’ve seen photos from DJ here before, from the 2014 Mid-Mesozoic Field Conference and the 2016 Sauropocalypse. Here’s an apatosaur pubis with some obvious bite marks on the distal end. This is on display next to a similarly-bitten ischium, which is shown in the MMFC14 post linked above.

Here’s a big apatosaur cervical, in antero-ventral view, with a dorsal rib draped over its left side. The cervical ribs are not fused in this specimen, so it was probably still growing. Here’s a labeled version:

The short centrum and nearly-vertical transverse processes indicate that this is a pretty posterior cervical, possibly a C13 or thereabouts. This specimen was over the fence in the exhibit area and I couldn’t throw a scale bar at it, but I’d describe it as “honkin'”. Like most of the apatosaur material at DJ, this vert is from the Mygatt-Moore Quarry.

Of course the real reason I was at Dinosaur Journey was to see the Snowmass Haplocanthosaurus that John Foster and I described back in 2014. You may remember that its caudal vertebrae have wacky neural canals. You may also have noticed a recent uptick in the number of posts around here about wacky neural canals. The game is afoot.

But as cool as they were, the Triassic tracks, the collared lizard, and even the Snowmass Haplo were only targets of opportunity. Brian and I had gone to Utah for this:

That photo was taken by Paige Wiren of Salt Lake City, on the day that she discovered that bone eroding out of a riverbank, just as you see it.

Here’s Paige with the element, which proved to be the left femur of an apatosaurine sauropod. It’s face down in these photos, so we’re looking at the medial side. The articular head is missing from the proximal end – it should be facing toward Paige’s right knee in the above photo – but other than that and a few negligible nicks and dings, the femur was complete and in really good shape.

Paige did the right thing when she found the femur: she contacted a paleontologist. Specifically, she asked a friend, who in turn put her in touch with Carrie Levitt-Bussian, the paleontology Collections Manager at the Natural History Museum of Utah. Based on Paige’s photos and maps, Carrie was able to identify the element as a dinosaur femur, probably sauropod, within the territory of the BLM Hanksville Field Office. John Foster, the Director of the Museum of Moab, has a permit to legally collect vertebrate fossils from that area, and he works on sauropods, so Carrie put Paige in touch with John and with ReBecca Hunt-Foster, the district paleontologist for the BLM’s Canyon Country District in Utah.

Now, I know there’s a lot of heated rhetoric surrounding the Bureau of Land Management, but whatever your political bent, remember this: those are our public lands. Therefore the fossils out there are the collective property of all of us, and we should all be upset if they get poached or vandalized. Yes, that is a big problem – the Brontomerus type quarry was partially poached before the bones we have now were recovered, and vandalism at public fossil sites in Utah made the national news while we were out there.

So that’s what we went to do: salvage this bone for science and education before it could be lost to erosion or asshats. Brian and I were out there to assist John, ReBecca, and Paige, who got to see her find come out of the ground and even got her hands dirty making the plaster jacket. Brian and John headed out to the site Friday morning and met up with Paige there, and ReBecca and I caravanned out later in the day, after I got back from Fruita.

But I’m getting ahead of myself a bit. We didn’t have to jacket the whole thing. It had naturally broken into three pieces, with thin clay infills at the breaks. So we just slid the proximal and middle thirds away as we uncovered them, and hit any loose-looking pieces with consolidant. The distal third was in more questionable shape, so we did make a partial jacket to hold it together.

We also got to camp out in gorgeous country, with spectacular (and welcome) clouds during the day and incredible starry skies at night.

We floated the femur out of the site using the Fosters’ canoe at the end of the day on Saturday, and loaded up to head back to Moab on Sunday. At one point the road was empty and the sky was not, so I stood on the center line and took some photos. This one is looking ahead, toward I-70 and Green River.

And this one is looking behind, back toward Hanksville.

Here are John and Brian with the femur chunks in one of the back rooms of the Museum of Moab. The femur looks oddly small here, but assembled it was 155 cm (5’1″) long and would have been 160 (5’3″) or more with the proximal head. Smaller than CM 3018 and most of the big mounted apatosaurs, but nothing to sneeze at.

What happens to it next? It will be cleaned, prepped, and reassembled by the volunteers and exhibit staff at the Museum of Moab, and eventually it will go on public display. Thousands of people will get to see and learn from this specimen because Paige Wiren made the right call. Go thou and do likewise.

That was the end of the road for the femur (for now), but not for Brian and me. We had business in Cedar City and St. George, so we hit the road Sunday afternoon. Waves of rainclouds were rolling east across Utah while we were rolling west, with breaks for sunlight in between. I miiiight have had to swerve a couple of times when all the scenery distracted me from driving, and I definitely made an obnoxious number of stops to take pictures.

I don’t remember which scenic overlook this was, but it was a pretty darned good view. This is another one that will reward embiggening – check out those mesas marching off into the distance.

In Cedar City we were guests of Andrew R.C. Milner, Site Paleontologist and Curator at the St. George Dinosaur Discovery Site at Johnson Farm (SGDS). We spent most of Monday at SGDS, getting our minds comprehensively blown by the amazing trace and body fossils on display. It was my first time visiting that museum, but it sure as heck won’t be the last.

I didn’t take nearly enough photos in St. George – too busy helping Brian do some filming for a future project – but I did get this gem. This is a Eubrontes track, from a Dilophosaurus-sized theropod. This is a positive track, a cast of the dinosaur’s foot made by sandy sediment that filled the natural mold formed when the dino stepped into mud. The high clay content of the mud recorded the morphology of the foot in fine detail, including the bumps of individual scales on the foot pads. The vertical streaks were cut into the side of the track by similar scales as the animal’s foot pushed into the mud.

The full story of the Johnson Farm tracks and trackmakers is beautifully told in the book Tracks in Deep Time: The St. George Dinosaur Discovery Site at Johnson Farm, by Jerry Harris and Andrew Milner. I hadn’t read it before, so I picked up a copy in the gift shop and I’ve been devouring it. As a professional scientist, educator, and book author myself, I’m jealous of what Jerry and Andrew produced – both the text and the abundant full-color illustrations are wonderfully clear, and the book is well-produced and very affordable.

From St. George we hit the road home, and rolled into Claremont just before midnight on Monday. It was a whirlwind tour – 1800 miles, three museums, and two fossil sites in six days – and my brain is still fizzing with all of the things we got to see and do.

One of the many pros of having a professional artist as a friend is that minimal hospitality, like letting him crash on my couch, is sometimes rewarded with original art. Brian was already gone when I got up Tuesday morning, but this was waiting for me on the dining room table. (Want your own? Help Brian make more monsters here.)

I owe plenty of thanks myself: to the Foster and Milner families for their near-maximal hospitality, to Julia McHugh of Dinosaur Journey for assistance in collections, to Diana Azevedo, Jalessa Spor, Jerry Harris, and the rest of the SGDS staff for being such gracious hosts, to Brian for being such a great friend and traveling companion, and most of all to Paige Wiren for finding the apato femur and helping us save it for science. You’re all top-notch human beings and I hope our paths cross again soon.

Here at SV-POW!, we’re just not having it.

Photo by Liguo Li, at the Academy of Natural Sciences in Philadelphia.

Also, because it’s only fair: Giant Irish Matt, to go with Giant Irish Mike. Don’t hold your breath for Giant Irish Darren – it just seems wrong to put antlers on the dude who invented Slinker World.