Please welcome Mirarce eatoni

November 13, 2018

Skeletal reconstruction of Mirarce by Scott Hartman (Atterholt et al. 2018: fig. 19). Recovered bones in white, missing bones in gray. The humerus is 95.9mm long.

Today sees the publication of the monster enantiornithine Mirarce eatoni (“Eaton’s wonderful winged messenger”) from the Kaiparowits Formation of Utah, by Jessie Atterholt, Howard Hutchinson, and Jingmai O’Connor. Not my critter, not my story, but it is SV-POW!-adjacent. (Just here for the paper? Here’s the link.)

Xiphoid process of sternum of Mirarce (Atterholt et al. 2018: fig. 5). Scale bar = 1cm.

As of this past summer, I knew that Jessie had a prehistoric monster coming out soon, and I knew that Brian Engh liked bringing prehistoric monsters to life, and I suspected that if the two reagents were combined, the rest of us might get something cool out of it.

Jessie and Brian talking about Mirarce, Utah for scale. July 13, 2018.

I did some heavy eavesdropping while the three of us were stomping around southern Utah looking for dinosaurs, so I got to hear Jessie and Brian batting ideas back and forth. By the end of our Utah trip Brian had sketches, and not long after, finished art (his post on Mirarce, including process sketches, is here). If you’ve seen one of my talks in the last month or so, you’ve gotten a teaser (with Jessie’s and Brian’s permission), and I know the piece got shown around a bit at SVP, too. You’ve waited long enough, here you go:

Not that the art is the whole story! Mirarce is a legitimately awesome find and Jessie and her coauthors poured a ton of work into the description. I’d tell you all about it, but much more capable and bird-fluent folks are on that already, and I have spinal cord and brainstem lectures to polish. So I’m gonna leave you with some links, which I’ll try to keep updated as different outlets get the story out:

Reference

Atterholt, J., Hutchinson, J.H.., and O’Connor, J.K. 2018. The most complete enantiornithine from North America and a phylogenetic analysis of the Avisauridae. PeerJ 6:e5910 https://doi.org/10.7717/peerj.5910

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The more I look at the problem of how flexible sauropod necks were, the more I think we’re going to struggle to ever know their range of motion It’s just too dependent on soft tissue that doesn’t fossilise. Consider for example the difference between horse necks (above) and camel necks (below).

The skeletons of both consist of vertebrae that are pronouncedly opisthocoelous (convex in front and concave behind), so you might think their necks would be similarly flexible.

But the balls of horse cevicals are deeply embedded in their corresponding sockets, while those of camels have so much cartilage around and between them that the tip of the ball doesn’t even reach the rim of the socket. As a result of this (and maybe other factors), camel necks are far more flexible than those of horses.

Which do sauropod necks resemble? We don’t currently know, and we may never know. It will help if someone gets a good handle on osteological correlates of intervertebral cartilage.

 


[This post is recycled and expanded from a comment that I left on a Tetrapod Zoology post, but since Tet Zoo ate that comment it’s just as well I kept a copy.]

Diverticulum, diverticula

November 4, 2018

This is not ‘Nam. This is Latin. There are rules.

The term for a small growth off an organ or body is diverticulum, singular, or diverticula, plural. There are no diverticulae or God forbid diverticuli, no matter what you might read in some papers. Diverticuli is a word – it’s the genitive form of diverticulum. But I’ve never seen it used that way in an anatomy or paleo paper. Diverticuli and diverticulae as alt-plurals for diverticulum are abominations that must be stomped out with extreme prejudice. If you want to get cute with alternative spellings, Wiktionary says you can use deverticulum. Wiktionary does not warn you that you will be mocked for doing so, but it is true nonetheless.

Stop jacking up straightforward anatomical terms, authors who should know better.

Here’s a swan. Unlike diverticuli and diverticulae, this unlikely morphology is real.

 

In a comment on the last post, Mike wrote, “perhaps the pneumaticity was intially a size-related feature that merely failed to get unevolved when rebbachisaurs became smaller”.

Caudal pneumaticity in saltasaurines. Cerda et al. (2012: fig. 1).

Or maybe pneumaticity got even more extreme as rebbachisaurids got smaller, which apparently happened with saltasaurines  (see Cerda et al. 2012 and this post).

I think there is probably no scale at which pneumaticity isn’t useful. Like, we see a saltasaurine the size of a big horse and think, “Why does it need to be so pneumatic?”, as if it isn’t still one or two orders of magnitude more massive than an ostrich or an eagle, both of which are hyperpneumatic even though only one of them flies. Even parakeets and hummingbirds have postcranial pneumaticity.

Micro CT of a female Anna’s hummingbird. The black tube in the middle of the neck is the supramedullary airway. Little black dots in the tiny cervical centra are air spaces.

We’re coming around to the idea that the proper way to state the dinosaur size question is, “Why are mammals so lousy at being big on land?” Similarly, the proper way to state the pneumaticity question is probably not “Why is small sauropod X so pneumatic?”, but rather “Why aren’t some of the bigger sauropods even more pneumatic?”

Another thought: we tend to think of saltsaurines as being crazy pneumatic because they pneumatized their limb girdles and caudal chevrons (see Zurriaguz et al. 2017). Those pneumatic foramina are pretty subtle – maybe their apparent absence in other sauropod clades is just because we haven’t looked hard enough. Lots of things have turned out to be pneumatic that weren’t at first glance – see Yates et al. (2012) on basal sauropodomorphs and Wedel and Taylor (2013b) on sauropod tails, for example.

Back of the skull of a bighorn sheep, showing the air spaces inside one of the broken horncores.

Or, even more excitingly, if the absence is genuine, maybe that tells us something about sauropod biomechanics after all. Maybe if you’re an apatosaurine or a giant brachiosaurid, you actually can’t afford to pneumatize your coracoid, for example. One of my blind spots is a naive faith that any element can be pneumatized without penalty, which I believe mostly on the strength of the pneumatic horncores of bison and bighorn sheep. But AFAIK sauropod girdle elements don’t have big marrow cavities for pneumaticity to expand into. Pneumatization of sauropod limb girdles might have come at a real biomechanical cost, and therefore might have only been available to fairly small animals. (And yeah, Sander et al. 2014 found a pneumatic cavity in an Alamosaurus pubis, but it’s not a very big cavity.)

As I flagged in the title, this is noodling, not a finding, certainly not certainty. Just an airhead thinking about air. The comment thread is open, come join me.

References

I did a fieldwork!

This is going to set new records for “almost too late to be worth posting”, but here goes.

First up, this Wednesday evening, Oct. 18, at 6:00 PM (in about 18 hours), while most of the paleontologists in the West are at SVP in Albuquerque, I will giving a public lecture at the Canyonlands Natural History Assocation’s Moab Information Center, at the corner of Main St. and Center in Moab (link). The talk is titled, “Lost worlds of the Jurassic: Diverse dinosaurs and plants in the lower Morrison Formation of south-central Utah”, and it is free to the public. It’s a report on the fieldwork I’ve been doing in the Morrison Formation of southern Utah for the past few summers with John Foster, Brian Engh, and Jessie Atterholt. I promise lots of pretty pictures and probably more yapping about sauropods than anyone really needs. Did I mention it’s free? I hope to see you there.

Second, I will be at SVP myself, for a bit. Basically Friday night and Saturday. Gotta catch up with collaborators and go see Brian Engh pick up his Lanzendorf Paleoart Prize Saturday night. Why do you care? Western University of Health Sciences has an open position for an anatomist, and a lot of paleo folks have anatomy training, so…if you are interested in this position specifically, or if you have general questions about what it’s like to be a paleontologist teaching gross anatomy at a med school (spoiler: mostly awesome), come find me sometime Friday evening or Saturday and chat me up. I’ll probably be roaming the hallways and talking with folks instead of attending talks (sorry, talk-givers–you all rock, I’m just too slammed this year). And if you are on the job market, have some anatomy experience, and aren’t allergic to sun, palm trees, and amazing colleagues, please consider applying for the position. We’re taking applications through October 26, so don’t tarry. Here’s that link again.

Last night, Fiona and I got back from an exhausting but very satisfying weekend spent at TetZooCon 2018, the conference of the famous Tetrapod Zoology blog run by Darren Naish — the sleeping third partner here at SV-POW!.

What made this particularly special is that Fiona was one of the speakers this time. She’s not a tetrapod zoologist, but a composer with a special interest in wildlife documentaries. She had half an hour on Music for Wildlife Documentaries – A Composer’s Perspective, with examples of her own work. I thought it was superb, but then I would — I’m biased. I’ll hand over to Twitter for a more objective overview:


Darren Naish: Now at #TetZooCon: Fiona Taylor on music in wildlife documentaries. Fiona is a professional composer.

Ellie Mowforth: Next up, it’s “Music for Wildlife Documentaries”. I am SHOCKED to hear that not everyone shares my love for the waddling penguin comedy trombone. #TetZooCon

Nathan Redland: Nature documentaries are entertainment, not just education: and the composer’s budget comes from the studio, not an academic institution #TetZooCon

“If these shows were just a string of facts about animals, most of us wouldn’t watch. That’s why they carve out stories in editing, why they use intense music, and why they recreate the sound effects — because story-telling is what engages us.”
— Simon Cade.

Will Goring: Very effective demonstration; same image, 5 different scores = 5 different interpretations. #TetZooCon

… and here is the relevant segment of video, together with the script that Fiona used:

Picture of wolf

We’re going to play “What kind of wolf is this?” or perhaps a better question is: “what is the music telling us to feel about this wolf?” I written 5 brief musical clips in 5 very different styles I’m hoping will showhow very differently we can be led into feeling about one image.

  1. This wolf is bad, suspense, about to kill something cute.
  2. Preparing to spring into action, attack.
  3. This wolf is sad, it has just lost its pups, if it doesn’t eat soon, it will starve.
  4. This wolf is cute, and cuddly and very playful. You just want to stroke him.
  5. This wolf is noble, kingly, will survive because his race has always survived, with dignity.

Alberta Claw: #TetZooCon Taylor: Provides detailed analysis of musical accompaniment in several documentary clips. Only a few seconds long each, but incredible amount of nuance and thought goes into these decisions.

Dr Caitlin R Kight: I responded exactly as she predicted and would have even without the explanation, but it was more interesting to know why I was feeling what I was, when I was!

Samhain Barnett: At 25 frames a second, a drumbeat has to occur within 2 frames of a nut being cracked, for our brains to accept it as in sync. Computers have made composers lives a lot easier here. #TetZooCon

(I’d like to show the video clip that that last tweet pertains to, but complicated rightsholder issues make that impractical. Sorry.)

Alberta Claw: #TetZooCon Taylor: Given the power of music to influence emotions, documentary composers have responsibility to think about the effects of music. Peer-reviewed research has shown that musical accompaniment can impact motivation of viewers to contribute to shark conservation.

Here are two sketches from Sara Otterstätter, who did this for every talk:

First one: About music in Nature documentaries. Useful or manipulative? #TetZooCon #sketch #sketchbook

Second one: Show documentaries always reality? #TetZooCon #Sketching #sketch

And two final comments …

Filipe Martinho: Quite often the most interesting talks are completely outside my area. Fiona Taylor gave an amazing eye and ear opener on the role of music in nature documentaries and #scicomm. #TetZooCon

Flo: Thanks to Fiona Taylor I will from now on listen more carefully to the music accompanying wildlife docs. #TetZooCon #musicforwildlifedocumentaries


We both had a great time at TetZooCon. As I said in an email to Darren after I got home, “It made me wonder what they heck I’d been thinking, missing the last few”. I don’t plan to repeat that mistake.

Hearing the talks through the ears of someone without much background was an interesting experience. Some of the speakers did a fantastic job of providing just enough background to make their work comprehensible to an intelligent layman: for example, Jennifer Jackson on whales, Robyn Womack on bird circadian rhythms and Albert Chen on crown-bird evolution. There’s a tough line to walk in figuring out what kind of audience to expect at an
event like this, and I take my hat off to those who did it so well.

 

My good friend, frequent collaborator, and fellow adventurer Brian Engh has won the John J. Lanzendorf Paleoart Prize for 2D paleoart (there are also categories for 3D paleoart and scientific illustration). He’s in august company; previous Lanzendorf winners include luminaries like John Gurche, Michael Skrepnick, Mark Hallett, Todd Marshall, and Julius Csotonyi (among many others–see the complete list of previous winners here). Naturally I’m happy as heck for Brian, and immensely proud of him, not only for the award, but also for what he’s doing now. Usually when we say “pay it forward” we mean metaphorically, but Brian is literally going to pay it forward. He’s created his own paleoart contest, the SummonENGH 2018, and he will award half of his October Patreon take to the winner.

He lays out the rules on his blog and in this video:

There’s a Facebook group, here, and a hashtag: #TheSummonEngh2018 (Facebook, Twitter).

Why do I think this is cool? It’s no exaggeration to say that I am a paleontologist today because I was exposed to mind-bending paleoart from a young age. Brian cares about paleoart–he cares about making better paleoart, himself, and he cares about making paleoart better, for everyone. And now he’s putting his money where his mouth his and doing something to hopefully bring more visibility to the paleoart community, and help move the field forward. That’s admirable, and I’m happy to support the cause.

Also, when we visited the Aquilops display at Dinosaur Journey this summer, we were lucky enough to capture this single frame showing a 100% real paleo-energy discharge. I definitely felt something at the time, but I didn’t know the full extent of what had happened until Brian sorted through our photos after the trip. Apparently this was all fated to happen–some kind of transdimensional chronoparticle emission linking past and future–and who am I to argue with fate?

Now, go summon monsters!