Thanks to a comment from long-time reader Andrew Stuck, I realised he is also the tweeter @dinodadreviews, who pointed us to Xenoposeidon in a kids’ book. Now, a review on his website of Ted Rechlin‘s comic-book Jurassic has pointed me to what I think is the first depiction of the BRONTOSMASH! hypothesis in a kids’ book:

This is nice work: it captures the mass of the animals, and resists the nearly ubiquitous tendency to make their necks too slender and elegant. The necks do look rather too short here, but I think we can explain that away as perspective foreshortening.

You’d have to say, though, that it owes more than a little inspiration to the third of Brian Engh’s early sketches:

I suppose there are only a certain number of ways to draw two apatosaurs fighting.

Anyway, it’s great to see what we consider a solidly supported palaeobiological hypothesis out there influencing young hearts and minds. We should also take this as a well-deserved prod to get on with the actual paper, which after all was meant to follow hard on the heels of our 2015 SVPCA presentation.

By the way, folks: the spelling and punctuation is “BRONTOSMASH!”. Not “Brontosmash”, not “BRONTOSMASH”: all in capitals, with an exclamation mark. It’s “the BRONTOSMASH! hypothesis”.

 

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Darren covered this briefly on the Scientific American version of Tetrapod Zoology, but the photos seem to have gone down and who knows how much longer any of that stuff will be up. Plus, he had other things to discuss, so the story has never been told in its entirety. This happened back in April, 2014. Here’s the full writeup I sent to Darren and Mike about it back when:

This happened Sunday afternoon and I thought you’d be interested. London and I let our box turtle, Easty (Terrapene carolina triunguis), crawl around the front yard on sunny days — with supervision, of course. She loves to dig around the edge of the sidewalk and flower bed and eat wood lice, worms, and whatever else comes her way. Sunday we saw her biting this biggish thing that from a distance looked like crumpled up paper. She was really going at it, so I got close to see what she was munching on. It was the head of a rat that our cat, Moe, had killed last week. Easty was snapping off bits of the braincase and eating them.

I had read of turtles scavenging carcasses for minerals but this was the first time I had observed it myself. She kept at it for about 20 minutes, until all of the thin, easily broken parts of the braincase were gone. She didn’t attempt to eat any of the facial skeleton or basicranium. Once she was done, she was done — I tossed the skull in front of her a couple of times and she would stop to smell it, but then walk past it, or even over it on one occasion.

So, there you have it, turtle eats part of rat skull. In keeping with my resolution to blog more about turtles, I’ll try to get some video of Easty feeding later this year. Right now she’s hibernating in a plastic tub on the bottom shelf of our refrigerator, so the hot turtle-feeding action will have to wait. Watch this space!

P.S. The gray ring on Easty’s shell in these photos is a sort of bathtub ring, from soaking in her water dish with just the top of her shell exposed, which she does for about six hours a day when she’s not hibernating. For pictures of Easty with a cleaner shell, please see the previous post. She really is a beautiful turtle.

Cool new paper out today by Yara Haridy and colleagues, describing the oldest known osteosarcoma in the vertebrate fossil record. The growth in question is on the proximal femur of the Triassic stem turtle Pappochelys.

Brian Engh did his usual amazing job illustrating this pervert turtle with no shell and a weird growth on its butt.

I don’t have a ton more to say about the paper, it’s short and sweet. I got to meet Yara in person at SVP last fall and learn about her research, and there is going to a LOT more weird stuff coming down the pike. She is after some really fundamental questions about where bone comes from, how it develops in the first place, and how it remodels and heals. Get ready to see some crazy jacked-up bones from other basal amniotes in the next few years, including some vertebrae that are so horked that Yara and I spent some time discussing which end was which.

On a probably inevitable and purely selfish personal note, I don’t blog nearly enough about turtles. I like turtles. Which, if you’re going to say, you gotta say like this kid:

In fact, I love turtles, and if there were no sauropods, I’d probably be working on turtles. Other people show you pictures of their cats, I’m going to show you pictures of my turtle, Easty. She’s a female three-toed box turtle, Terrapene carolina triunguis.

Here she is closing in on an unlucky roly-poly (or pill bug, if you prefer).

Having a close encounter with our cat Berkeley last summer. I think Easty kinda blew Berkeley’s mind. She’s been around our other cat, Moe, for years, so she’s completely unfazed by cats. But Berkeley is a SoCal kitty who showed up on our doorstep starving and yowling when he was about eight weeks old, so this was his first encounter with a turtle.

Berkeley batted at Easty’s shell a couple of times and then spent about half an hour having a visible existential crisis. Here was a small creature that he couldn’t frighten and couldn’t move, which was not the least bit afraid of him and either ignored him or treated him like an obstacle. Watching them interact — or rather, watching Easty act and Berkeley react — was solid entertainment for most of the afternoon.

Why have I hijacked this post to yap about my turtle? Primarily because up until now I’ve had a hard time visualizing a stem turtle. Turtles are so much their own thing, and I’ve been so interested in them for virtually my entire life, that imagining an animal that was only partly a turtle was very difficult for me. The thing I like most about Brian’s art of the tumorous Pappochelys is that it reads convincingly turtle-ish to me, especially the neck and head:

So congratulations to Yara and her coauthors for a nice writeup of a very cool find, and to Brian for another vibrant piece of paleoart. Triassic turtles sometimes had cancer on their butts. Tell the world!

Since I’ve already blown the weekly schedule here in the new year, maybe my SV-POW! resolution for 2019 will be to blog more about turtles. I’m gonna do it anyway, might as well make it a resolution so I can feel like I’m keeping up with something. Watch this space.

Reference

Sorry for the short notice, but I just wanted to let you all know:

Today is Academic-Led Publishing Day, which the official website describes as “a global digital event to foster discussions about how members of the scholarly community can develop and support academic-led publishing initiatives”. More informally, it’s about how we can throw off the shackles of “publishers” that have made themselves our masters rather than our servants.

Three events are scheduled today: an OASPA Webinar, showcasing examples of excellent in academic-led publishing initiatives; a Twitter chat; and a panel discussion — see the website for details. These involve some stellar people, plus me. Seriously: I have no idea what I am doing there alongside people like Kathleen Shearer, Executive Director of the Confederation of Open Access Repositories, and Rebecca Kennison, co-founder of the Open Access Network. But it’s a privilege to be involved and I hope I can add something to the discussion.

If you want to tune in, you can watch live on YouTube starting at 2pm Eastern time, which is 7pm GMT. I hope to see some of you there!

BTW., if the whole topic of academic-led publishing is new to you, you might find this blog-post by Scholastica helpful: they are one of the leading publishers in this area, and right behind the goal of putting academics back in charge of academic publishing. Read: Why Academic-Led Journal Publishing? Liberating Research Through Tools and Services

I was delighted today to see a tweet from dinodadreviews:

(Here is it, archived, in case it goes away for any reason):

Another kid’s book featuring @MikeTaylor’s baby, Xenoposeidon! Seen in this “#Alphasaurs” book as its old brachiosaurus interpretation, I love the “X-ray” flap showing the approximate location of its one known bone! 🦕

This is a nice, elegant bit of artwork, based of course on the old brachiosaurid interpretation of Xenoposeidon — which has been superseded by the new rebbachisaurid interpretation, but the author and designer weren’t to know that.

My only reservation, really, is that the pronunciation isn’t quite right. There’s no real excuse for that as I gave it right in the paper: it should be “ZEE-no-puh-SYE-d’n”. Oh well.

The inspiration for the book illustration will have been this image:

which we used in Post 4 of the original Xenoposeidon week, and also in my old, pre-SV-POW! web-page about it. That in turn came from this one:

which I made as a joke and described as “the first scientifically rigorous skeletal reconstruction of Xenoposeidon. As the Day-four post says, “I thought it would be funny to do this for an animal known only from a single bone, showing the bone floating in the middle of a big black silhouette. Har har.” It’s funny, now, twelve years later, to the see the descendent of that image in a kids’ book.

Finally, these Xenoposeidon “reconstructions” were based on the solid work that Matt had done on a Brachiosaurus reconstruction (actually Giraffatitan, but back then we thought the latter was a species of the former) to be used in the papers about Sauroposeidon:

Matt wrote a short paper for Prehistoric Times about his work on this reconstuction. It’s only one page: go and read it.

dinodadreviews’ tweet was the first I’ve heard of the Alphasaurs book, but following the #Alphasaurs hashtag took me to a tweet by the book’s designer, which in turn took me to the book’s Amazon page. And there, I was surprised but pleased to see the Xenoposeidon gets the star billing in the Booklist review:

“X marks the spot” for Xenoposeidon. In this alpha-bestiary, the X denoting the only bone found for this long-necked dinosaur—from which its entire structure has been extrapolated—is cut into a flap that, when lifted, reveals Xenoposeidon’s very, very long tail. This dinosaur, like the other 25 who walk, swim, fly, and prowl through these foldout pages, is made up of hundreds of the first letter of its name. Check out the red capital As that mark Allosaurus’ fangs, or the vicious-looking Vs of the Velociraptor’s claws, or the way the Ws of Wuerhosaurus form spikes on its dangerous tail. Each of the dinosaurs showcases a different typeface, too (all the typefaces are identified at the book’s end). Meanwhile, fast facts about dinosaurs fill the margins. There is little doubt the strange art will reel them in—and probably keep them reading. A wholly unique mix of typography and dinosaur science. Grades 1-3. — Connie Fletcher

I’m not quite sure how Connie Flecher concluded that the lift-the-flap reveals the tail, but I’m prepared to give her a pass since the had the good judgement to lead with Xeno.

 

 

Birds have little blobs of tissue sticking out on either side of the spinal cord in the lumbosacral region (solid black arrow in the image above). These are the accessory lobes of Lachi, and they are made up of mechanosensory neurons and glycogen-rich glial cells (but they are not part of the glycogen body, that’s a different thing that lies elsewhere — see this post).

These accessory lobes have been known since at least 1889, when they were first described by Lachi. But the function was mysterious until recently.

Starting in the late 1990s, German anatomist and physiologist Reinhold Necker investigated the development, morphology, and function of the lumbosacral canals of birds. These are not pneumatic spaces, they’re fluid-filled tubes that arch above (dorsal to) the spinal cord in the lumbosacral regions of birds. In a sacral neural canal endocast they look like sets of ears, or perhaps caterpillar legs (below image in the above slide).

Here’s the same slide with the top image labeled, by me.

In our own bodies, the meningeal sac that surrounds the spinal cord is topologically simple, basically a single long bag like a sock with the spinal cord running through the middle. In the lumbosacral regions of birds, the meningeal sac is more like a basket in cross-section, with dorsally-arching loops — the lumbosacral canals — forming the basket handles (lower image in the above slide). Evidently cerebrospinal fluid can slosh through these meningeal loops and push on the accessory lobes of Lachi, whose mechanosensory neurons pick up the displacement. This is essentially the same system that we (and all other vertebrates) have in the semicircular canals in our inner ears, which give us our sense of equilibrium.

Evidence that the lumbosacral canals function as organs of equilibrium comes not only from anatomy but also from the behavior of experimentally-modified birds. If the lumbosacral canals are surgically severed, creating the ‘lesion’ mentioned in the above figure, the affected birds have a much harder time controlling themselves. They can do okay if they are allowed to see, as shown on the left side of the above figure, but if they are blindfolded, they don’t know how to orient themselves and flop around clumsily. Meanwhile, blindfolded birds with their lumbosacral canals intact can balance just fine.

All of this is documented in a series of papers by Necker and colleagues — particularly useful are Necker (1999, 2002, 2005, 2006) and Necker et al. (2000). Necker (2006) seems to be the summation of all of this research. It’s very well-documented, well-reasoned, compelling stuff, and it’s been in the literature for over a decade.

So why is no-one talking about this? When I discovered Necker’s work last spring, I was stunned. This is HUGE. In general, the central nervous systems of vertebrates are pretty conserved, and animals don’t just go around evolving new basic sensory systems willy-nilly. Minimally I would expect congressional hearings about this, broadcast live on C-SPAN, but ideally there would be a talk show and a movie franchise.

I was equally blown away by the fact that I’d never heard about this from inside the world of science and sci-comm. Necker’s discovery seemed to have been almost entirely overlooked in the broader comparative anatomy community. I searched for weaknesses in the evidence or reasoning, and I also searched for people debunking the idea that birds have balance organs in their butts, and in both cases I came up empty-handed (if you know of counter-evidence, please let me know!). It’s relevant to paleontology, too: because the lumbosacral canals occupy transverse recesses in the roof of the sacral neural canal, they should be discoverable in fossil taxa. I’ve never heard of them being identified in a non-avian dinosaur, but then, I’ve never heard of anyone looking. You can also see the lumbosacral canals for yourself, or at least the spaces they occupy, for about three bucks, as I will show in an upcoming post.

Incidentally, I’m pretty sure this system underlies the axiomatic ability of birds to run around with their heads cut off. I grew up on a farm and raised and slaughtered chickens, so I’ve observed this firsthand. A decapitated chicken can get up on its hind legs and run around. It won’t go very far or in a straight line, hence the jokey expression, but it can actually run on flat ground. It hadn’t occurred to me until recently how weird that is. All vertebrates have central pattern generators in their spinal cords that can produce the basic locomotor movements of the trunk and limbs, but if you decapitate most vertebrates the body will just lie there and twitch. The limbs may even make rudimentary running motions, but the decapitated body can’t stand up and successfully walk or run. Central pattern generators aren’t enough, to run you need an organ of balance. A decapitated bird can successfully stand and run around because it still has a balance organ, in its lumbosacral spinal cord.

You may recognize some of the slides that illustrate this post from the Wedel et al. (2018) slide deck on the Snowmass Haplocanthosaurus for the 1st Palaeontological Virtual Congress. Those were stolen in turn from a much longer talk I’ve given on weird nervous system anatomy in dinosaurs, which I am using piecemeal as blog fuel. Stay tuned!

So, birds have balance organs in their butts. We should be talking about this. The comment thread is open.

References

  • Lachi, P. 1889. Alcune particolarita anatomiche del rigonfiamento sacrale nel midollo degli uccelli. Lobi accessori. Att Soc Tosc Sci Nat 10:268–295.
  • Necker, R. 1999. Specializations in the lumbosacral spinal cord of birds: morphological and behavioural evidence for a sense of equilibrium. European Journal of Morphology 37:211–214.
  • Necker, R. 2002. Mechanosensitivity of spinal accessory lobe neurons in the pigeon. Neuroscience Letters 320:53–56.
  • Necker, R. 2005. The structure and development of avian lumbosacral specializations of the vertebral canal and the spinal cord with special reference to a possible function as a sense organ of equilibrium. Anatomy and Embryology 210:59–74.
  • Necker, R. 2006. Specializations in the lumbosacral vertebral canal and spinal cord of birds: evidence of a function as a sense organ which is involved in the control of walking. Journal of Comparative Physiology A, 192(5):439-448.
  • Necker, R, Janßen A, Beissenhirtz, T. 2000. Behavioral evidence of the role of lumbosacral anatomical specializations in pigeons in maintaining balance during terrestrial locomotion. Journal of Comparative Physiology A 186:409–412.
  • Wedel, M.J., Atterholt, J., Macalino, J., Nalley, T., Wisser, G., and Yasmer, J. 2018. Reconstructing an unusual specimen of Haplocanthosaurus using a blend of physical and digital techniques. Abstract book, 1st Palaeontological Virtual Congress, http://palaeovc.uv.es/, p. 158 /  PeerJ Preprints 6:e27431v1

In short, no. I discussed this a bit in the first post of the Clash of the Dinosaurs saga, but it deserves a more thorough unpacking, so we can put this dumb idea to bed once and for all.

As Marco brought up in the comments on the previous post, glycogen bodies are probably to blame for the idea that some dinosaurs had a second brain to run their back ends. The glycogen body is broadly speaking an expansion of the spinal cord, even though it is made up of glial cells rather than neurons — simply put, help-and-support cells, not sensory, motor, or integration cells. When the spinal cord is expanded, the neural canal is expanded to accommodate it; as usual, the nervous system comes first and the skeleton forms around it. This creates a cavity in the sacrum that is detectable in fossils.

avian lumbosacral specializations - glycogen body

Giffin (1991) reviewed all of the evidence surrounding endosacral enlargements in dinosaurs (primarily sauropods and stegosaurs) and concluded that the explanation that best fit the observations was a glycogen body like that of birds. I agree 100%. The endosacral cavities of sauropods and stegosaurs (1) expand dorsally, instead of in some other direction, and (2) expand and contract over just a handful of vertebrae, instead of being more spread out. Of the many weird specializations of the spinal cord in birds, the glycogen body is the only one that produces that specific signal.

If any part of the nervous system of birds and other dinosaurs might be described as a ‘second brain’, it wouldn’t be the glycogen body, it would be the lumbosacral expansion of the spinal cord, which really is made up of neurons that help run the hindlimbs and tail (more on that in this previous post). But there’s nothing special about that, it’s present in all four-limbed vertebrates, including ourselves. Interestingly, that bulk of extra neural tissue in the sacral region of birds was referred to as a sort of ‘second brain’ by Streeter way back in 1904, in reference to the ostrich, but it’s clear that he meant that as an analogy, not that’s it’s literally a second brain.

So to sum up, a gradual expansion of the spinal cord to help run the hindlimbs and tail IS present in dinosaurs — and birds, and cows, and frogs, and us. But if that qualifies as a ‘second brain’, then we also have a ‘third brain’ farther up the spinal cord to run our forelimbs: the cervical enlargement, as shown in the above figure. These spinal expansions aren’t actual brains by any stretch and referring to them as such is confusing and counterproductive.

The sharp expansion of the neural canal over just a few vertebrae in birds does not house a ‘second brain’ or even an expansion of the neural tissue of the spinal cord. It contains the glycogen body, which is not made of neurons and has no brain-like activity. The sacral cavities of non-avian dinosaurs replicate precisely the qualities associated with the glycogen bodies of birds, and there’s no reason to expect that they contained anything else. That we don’t know yet what glycogen bodies do, even in commercially important species like chickens, may make that an unsatisfying answer, but it’s what we have for now.

The next installment will be way weirder. Stay tuned!

References

  • Giffin, E.B.,1991. Endosacral enlargements in dinosaurs. Modern Geology 16: 101-112.
  • Streeter, G.L. 1904. The structure of the spinal cord of the ostrich. American J. Anatomy 3(1): 1-27.