I’ve been in contact recently with Matt Lamanna, Associate Curator in the Section of Vertebrate Paleontology at the Carnegie Museum of Natural History — which is obviously the best job in the world. Among a batch of photos that he sent me recently, I seized on this gem:

Tyrannosaurus rex, Diplodocus carnegii, Apatosaurus louisae and multiple mostly juvenile individuals of Homo sapiens. Photograph taken between 1941 and 1965. Courtesy of Carnegie Museum of Natural History.

There’s so much to appreciate in this picture: the hunchbacked, tail-dragging Tyrannosaurus; the camarasaur-style skull on the Apatosaurus; the hard-to-pin-down archaic air of Diplodocus.

But the thing I love about it is the 1950s kids. (Or, to be fair, maybe the 1940s kids or early 1960s kids, but you get the point.) They way they’ve all been asked to look up at the tyrannosaur skull, and are obediently doing it. How earnest they all appear. How they’re all dressed as tiny adults. How self-consciously some of them have posed themselves — the thoughtful kid one in from the left, his foot up on the plinth and his chin resting on his hand; the cool kid to his right, arms crossed, interested but careful not to seem too impressed.

Where are these kids now? Assuming it was taken in 1953, the midpoint of the possible range, and assuming they’re about 12 years old in this photo, they were born around 1941, which would make them 81 now. Statistically, somewhere around half of them are still alive. I wonder how many of them remember this day, and the strange blend of awe, fascination, and self-consciousness.

This is a time-capsule, friends. Enjoy it.

We’ve shown you the Apatosaurus louisae holotype mounted skeleton CM 3018 several times: shot from the hip, posing with another massive vertebrate, photographed from above, and more. Today we bring you a world first: Apatosaurus from below. Scroll and enjoy!

Obviously there’s a lot of perspective distortion here. You have to imagine yourself lying underneath the skeleton and looking up — as I was, when I took the short video that was converted into this image.

Many thanks to special-effects wizard Jarrod Davis for stitching the video into the glorious image you see here.

The most obvious effect of the perspective distortion is that the neck and tail both look tiny: we are effectively looking along them, the neck in posteroventral view and the tail in anteroventral. The ribs are also flared in this perspective, making Apato look even broader than it is in real life. Which is pretty broad. One odd effect of this is that this makes the scapulae look as though they are sitting on top of the ribcage rather than appressed to its sides.

 

Remember this classic XKCD comic?

You should talk to the girl down the hall; I think you'd like her. Lemme know if you find out why she's ordering all those colored plastic balls.

Well, this is me over the last couple of weeks:Isn't it weird how looking at those cervicals in either lateral OR dorsal views gives a completely misleading idea of their shape?

Starlings are amazing

October 29, 2021

Back in May, Amy Schwartz posted a photo of a starling that shethat had ringed that morning:

Impressed by the subtlety of the coloration, I wondered what would happen if I increased the colour saturation. I did this very simply: in the free image editor GIMP, I selected the parts of the photo that were starling (omitting the human hand and the background), and using the Hue-Saturation tool I wound the saturation up to 100%. Then I did the same thing again. Here is the result, with no other editing at all:

What an extraordinary riot of colour, in a bird that we mostly think of as “basically black with dots.”

So I thought I’d try the same trick on another starling photo, this one from the All About Birds page on the European Starling. Here is the original:

And here is the result of saturating the colours — this time through three cycles.

So my question is this: can other starlings see all this colour? In their own closed starling-centric world, are they fabulously colourful? Is this something close to what is perceptually apparent to animals whose eyes are attuned to different wavelengths from ours?that

My Oct. 13 National Fossil Day public lecture, “Lost Giants of the Jurassic”, for the Museums of Western Colorado – Dinosaur Journey is now up on their YouTube channel. First 48 minutes are talk, last 36 minutes are Q&A with audience, moderated by Dr. Julia McHugh. New stuff from the 2021 field season — about which I’ll have more to say in the future — starts at about the 37-minute mark. Hit the 44-minute mark (and this and this) to find out what to do with all of the unwanted bird necks that will be floating around at the upcoming holidays.

Finally, big thanks to Brian Engh for finding our brachiosaur and for letting me use so much of his art, to John Foster, Kaelen Kay, Tom Howells, Jessie Atterholt, Thierra Nalley, and Colton Snyder for such a fun field season this year, and to Julia McHugh for giving me the opportunity to yap about one of my favorite dinosaurs!

Back in 2017, I showed the world 83.33% of my collection of sauropod-themed mugs. Time passes, and I have lost some of them and gained some more. The tally now stands at eight, and here they are:

My missing Brontomerus mug never did turn up. In the mean time, I have also lost or maybe broken the Sauroposeidon mug, the old black-and-white Archbishop mug, and the single-view Xenoposeidon mug. The dissertation mug still survives, but has faded into total illegibility, so I don’t count it any more.

On the more positive side, the sexual selection mug — second from the right in the old photo, and bottom left in the new one — survives, in fact the only one to have done so. All the others are new acquisitions. Let’s take a look:

Back row, left to right:

  1. The new, improved Archbishop dorsals A and B mug. Unlike the original, this is in glorious colour, and rearranges the elements to show anterior view on the front, and left and right lateral on the sides.
  2. The new, improved Xenoposeidon mug. It’s laid out the same way with the anterior view on the front and left and right lateral views on the sides.
  3. One that Fiona made for my birthday, showing one of the publicity photos from the original Xenoposeidon description: the one of which a newspaper columnist wrote “I wish my husband looked at me the way he looks at this bone”.
  4. A mug made by Mark Witton, which I saw at TetZooCon 2019 and made him an offer for. It shows his own Diplodocus artwork, an update of an earlier piece that he did for Matt, Darren and me to publicise our 2009 paper on sauropod neck posture. (Details here.)

Front row, left to right:

  1. The sole survivor, showing the introductory here’s-what-sauropod-necks-are-like illustration from our 2011 paper on why those necks were not sexually selected.
  2. The sauropod neck gallery used as Figure 3 in my and Matt’s 2013 PeerJ paper “why giraffes have short necks”.
  3. One of the world’s few caudal pneumaticity mugs, using all the illustrations from Matt’s and my 2013 paper, and inspired by the freakily consistent colour palette of those illustrations.
  4. This one needs a bit of explaining. See below.

For reasons that no-one — least of all he — understands, my youngest son bought a pair of Dawn French mugs as a birthday or Christmas present for Fiona. (No-one in our family is particularly a fan, it was one of those random things.) Since then, he has given her five or six more identical mugs.

Because I do not like these, I insist that they hang on one mug tree, and the sauropod mugs on another. It was to break down this mug apartheid that our eldest made for us this final mug, which shows both Dawn French and a reconstruction of the Xenoposeidon vertebra (from my 2018 paper). Where does it live? Usually, it sits on the shelf between the two mug trees.

So this is how things stand. (I drink a lot of tea, so these mugs all see plenty of action.) I really should make myself a new Brontomerus mug, and perhaps a pneumatic variation one.

The early armored fish Bothriolepis, which Yara Haridy affectionately refers to as a “beetle mermaid”. Art by Brian Engh, dontmesswithdinosaurs.com.

If I had to sum up my main research program over the past 20+ years, it would be, “Why pneumatic bone?” Or as I typically put it in my talks, most bone has marrow inside, so if you find bone with air inside, someone has some explaining to do (f’rinstance).

One of the reasons I like hanging out with Yara Haridy is that she is interested in an even more fundamental question: “Why bone?” And also “How bone?” And she has a paper out today that gives us new insights into the form and function of bone cells — osteocytes — in some of the earliest vertebrates that had them (Haridy et al. 2021; if you’re in TL;DR mode, here’s the link). 

Bones have multiple functions in vertebrate bodies: they’re a mechanical framework for our muscles, and a mineral reservoir, and form armor in many taxa, and are involved in hormone regulation, and doubtless other things that we are still discovering, even now. To fulfill those functions, bone tissue has to be formed in the first place, it has to be maintained, and it has to be able to be reshaped as an individual grows. Derived extant vertebrates, including humans, have an impressive array of cellular machinery to make all those things happen. Central to most of those operations are osteocytes, the cells inside living bone, which maintain intimate connections to extracellular bone tissue and to other osteocytes via fine, tentacle-like processes.

Individual osteocytes look something like the Flying Spaghetti Monster. The central portion of the FSM, with the meatballs, is the osteocyte body, and the noodly appendages are the processes.

Now imagine that you cloned the FSM many, many times, and the resulting array of FSMs stayed in physical contact with each other via their noodly appendates, forming a network.

Then imagine that you entombed all of the cloned FSMs in concrete. This is more or less what cellular bone — the kind you find in humans, dinosaurs, and even some jawless fish — looks like on the microscopic scale: osteocytes (the FSMs) and their processes (the noodly appendages) embedded in space-filling stuff (the bone matrix). Some critters, including teleost fish, have acellular bone, but I don’t have time for those unbelievers today.

When an animal dies and decomposes, the osteocytes and their processes decay away, leaving behind the spaces that they used to occupy. The big spaces that hold osteocytes are called lacunae, and the little tunnels that hold the osteocyte processes (noodly appendages, in this metaphor) are canaliculi. Collectively, the lacunae and canaliculi form the lacunocanalicular network or LCN.

Those spaces can then be filled by matrix — not extracellular bone matrix, but future rock matrix, like mud and clay. In point of fact, not all of the spaces are filled with matrix. Even in their 420-million-year-old fish, Yara and colleagues found some osteocyte lacunae that had not been filled with matrix, and were filled by air instead. Whether the lacunocanalicular network is filled with matrix or air, its preservation in fossil bone has turned out to be a boon for paleontologists, because we can ‘see’ the sizes and shapes of osteocytes, and their level of connectivity, by studying the lacunae and canaliculi they left behind. 

Histological thin section of bone in the osteostracan Tremataspis mammillata (MB.f.TS.463), imaged with transmitting light microscopy showing osteocyte lacunae (osl) and canaliculi (ca); scale bar, 100 microns. Haridy et al. (2021: fig 2A).

Traditionally osteocyte lacunae and canaliculi in fossil bone have been imaged by taking thin sections of the specimens and looking at them under microscopes.

Synchrotron tomography of bone of Bothriolepis trautscholdi (MB.f.9188a) with the vasculature and osteocytes segmented; scale bar, 0.4 mm. (D) Close-up of tomography in (C) showing the resolution of the osteocyte lacunae volumes; scale bar, 10 microns. bs, bone sample; vs, vasculature channels. Modified from Haridy et al. (2021: fig. 2C-D).

If you’re fancy, you can also do synchrotron tomography, which is fine enough to show osteocyte lacunae — the colored blobs in the image on the right, above.

Those methods have their limitations. Light microscopy will reveal both lacunae and canaliculi in 2D, but it’s hard to get a 3D understanding of the lacunocanalicular network that way (at least in fossils; in modern samples it can be done with confocal miscoscopy). Synchrotron tomography can resolve lacunae in 3D, but not canaliculi, sort of like a map that shows only cities but not the highways that connect them.

Enter FIB-SEM: focused ion beam scanning electron microscopy. An ion gun blasts the specimen with a beam of gallium ions, which vaporizes a slice of the specimen that is less than 1 micron thick, and an SEM images the freshly exposed face. If you do this over and over again, you can build up a 3D model of the stuff that once occupied the volume that got zapped. 

FIB-SEM tomography imaging and processing of the fossil jawless vertebrate Tremataspis mammillata (MB.f.9025). (A and B) FIB-SEM setup showing the FIB in relation to the SEM both aimed at the region of interest. (C) Bone surface with an excavate area made by the FIB. (D) Internal wall of the excavated area lined with small black dots that are the fossil osteocyte lacunae. (E) Single osteocyte lacuna from the surface that is scanned; the single SEM image shows the lacunae and canaliculi in black and the mineralized bone in gray; scale bar, 5 microns. (F and G) An image stack is obtained, and 3D made of fossil LCN can be made. Haridy et al. (2021: fig 3).

FIB-SEM is fine enough to resolve both osteocyte lacunae and canaliculi — the lacunocanalicular network or LCN — in three dimensions, in fossil specimens where confocal light microscopy doesn’t always work very well. And the resolution is pretty insane. The rough edges on the 3D models of the LCN aren’t sampling artifacts, they’re accurately reflecting the real morphology of the walls of the lacunae and canaliculi as they were preserved in the fossil bone.

But wait — that’s not all! Not only can FIB-SEM show us osteocyte lacunae and canaliculi in incredible detail in three dimensions, it can also help us figure out at least some of what osteocytes were doing. Together, osteocytes and their processes can sense mechanical strain in bone, trigger bone remodeling, and resorb and lay down bone from the walls of the lacunae and canaliculi. That last process starts with osteocytic osteolysis — the resorption of bone matrix (= osteolysis) from the lacunae and canaliculi by the osteocytes themselves (as opposed to the more familiar destruction of bone at a larger spatial scale by osteoclasts), which is typically followed by the replacement of new matrix where the old bone used to be. Lots of extant vertebrates do osteocytic osteolysis, especially those that have a high demand for calcium and phosphorus in physiologically challenging times. Examples including migrating salmon, lactating mice, and lactating humans. But when did that capacity evolve — did the earliest osteocytes already have the ability to resorb and replace bone? As Yara said to me when she was telling me about her new paper, “We think we know how things work by looking at extant animals, but we’re looking at this highly pruned tree, and we can’t just assume that things worked the same way earlier in our evolutionary history.” 

Yara wanted to investigate when osteolytic osteolysis first evolved when she started her dissertation in 2018, but she didn’t know that FIB-SEM existed. Then she was visiting a neutron tomography facility in Berlin and she saw a poster on the wall about people using FIB-SEM to image corrosion in batteries on ultra-fine scales. She thought, “Wow, the corrosion pits in the batteries look like osteocytes!” The rest you probably figured out faster than it’s taking me to write this sentence: together with her collaborators, she got some samples of bone from the jawless fish Tremataspis and Bothriolepis and zapped them with the FIB-SEM.

Osteocytic osteolysis as a mechanism for early mineral metabolism. (A to C) Illustrations depicting the process of osteocytic osteolysis; the phases are stasis phase, dissolution phase, and redeposition phase, respectively. (D) Single SEM image from the FIB-SEM acquisition showing the air-filled osteocyte lacunae and canaliculi of T. mammillata. (E) Same SEM image as in (D) with contrast shifted to show the demineralized zone surrounding the lacunae. (F and G) 3D render of the stack of images from (D and E) T. mammillata (MB.f.9025). The 3D model shows several osteocytes and their canaliculi, with the red areas showing where the “areas of low density” were found. ald, area of low density; os, osteocyte. Scale bar, 5 microns.

And, wonder of wonders, some of the osteocyte lacunae in Tremataspis were surrounded by a halo of less-dense bone, which is evidence for osteocytic osteolysis. Now, Yara and colleagues can’t be sure whether the bone is less dense because it was being resorbed when the animal died — the actual lytic or bone-destructive phase — or because new bone was being laid down after the old bone had been resorbed; naturally the new bone is less dense as it being formed than it will be when it is complete. They also can’t be sure why the process was occurring in that one individual Tremataspis. Mice only do osteocytic osteolysis when they’re lactating, and salmon only do it when they’re migrating, so the presence of osteocytic osteolysis might indicate that the Tremataspis in question was doing something stressful related to its ecology or life history — both topics we know almost nothing about.

Yara and colleagues didn’t find any evidence of osteocytic osteolysis in their Bothriolepis sample, but this is one of those ‘absence of evidence is not evidence of absence’ things — you wouldn’t find evidence of osteocytic osteolysis in my skeleton either, despite a long ancestral history, because I’m skeletally healthy, not fasting or migrating, and not lactating. Possibly other Bothriolepis individuals that were going through a rough patch, metabolically speaking, would show osteocytic osteolysis. So far, as a species, we’ve only looked at the one sample, from the one individual.

I asked Yara what she wanted people to take away from her new paper. Her response:

  1. We have technology can image fossil bone cells at the same resolution that we can see modern bone cells.
  2. Bone metabolism was going on 420 million years ago, in the earliest osteocytes, the same way it happens in modern mammals, including humans. 

I expect that we will see a lot more FIB-SEM papers on fossils in years to come. That research program started today, with the publication of Haridy et al. (2021). I often sign off posts with “stay tuned”, and this time I really mean it.

Reference

Yara Haridy, Markus Osenberg, André Hilger, Ingo Manke, Donald Davesne, and Florian Witzmann. 2021. Bone metabolism and evolutionary origin of osteocytes: Novel application of FIB-SEM tomography. Science Advances 7(14): eabb9113. DOI: 10.1126/sciadv.abb9113.

Gilmore (1936:243) says of the mounted skeleton of Apatosaurus louisae CM 3018 in the Carnegie Museum that “with the skull in position the specimen has a total length between perpendiculars of about 71 feet and six inches. If the missing eighteen terminal caudal vertebrae were added to the tip of the tail, in order to make it conform to known evidence, the skeleton will reach an estimated length of 76 feet, 6 inches.” That’s 23.3 meters.

But what if it was 800 meters long instead? That would be 34.3 times as big in linear dimension (and so would mass 34.3^3 = 40387 time as much, perhaps a million tonnes — but that’s not my point).

What would a cervical vertebra of an 800m sauropod look like?

Gilmore (1936:196) gives the centrum length of CM 3018’s C10 as 530 mm. In our 34.3 times as long Apatosaurus, it would be 18.17 meters long. So here is what that would look like compared with two London Routemaster buses (each 8.38 meters long).

Cervical vertebra 10 of a hypothetical 800 meter long Apatosaurus louisae, with London Routemaster buses for scale. Vertebra image from Gilmore 1936:plate XXIV; bus image by Graham Todman, from Illustrations for t-shirts.

What is the research significance of this? None at all, of course. Still I think further study is warranted. Some look at sauropods that once were, and ask “why?”; but I go further; I look at sauropods that never were, and ask “why not?”

 

These are nice. Click through to empiggen.

I ripped them from Parker (1874), which appears to be a free download from JSTOR, here, and tweaked the colors just a bit.

If you are here for serious science, these guides to the abbreviations used in the plates will come in handy. I hacked the second one, below, to include the descriptions of the plates above, which are the last in the series, not the first.

EDIT: Nick Gardner pointed out that the copy of Parker (1874) at the Biodiversity Heritage Library is a slightly sharper scan, so if you’d prefer that version, it’s here.

Reference

Parker, W.K. 1874. On the structure and development of the skull in the pig (Sus scrofa). Philosophical Transactions of the Royal Society of London 164: 289-336.

 

This beautiful image is bird 52659 from Florida Museum, a green heron Butorides virescens, CT scanned and published on Twitter.

(The scan is apparently from MorphoSource, but I can’t find it there.)

There is lots to love here: for example, you can see that the long bones of the arm are pneumatic, because the margins of the bones show up more strongly than the cores. But you won’t be surprised that I am interested mostly in the neck.

As you can see, while the vertebrae of the neck are pulled back into a strong curve, the trachea doesn’t bother, and just sort of hangs there from the base of the head to the top of the lungs, cheerfully crossing over (i.e. passing to the side of) the vertebral sequence. So the trachea here is not much more than half the length of the vertebral sequence.

Now this is the opposite of what we see in some birds. Here, for example, is a trumpet manucode Phonygammus keraudrenii (a bird-of-paradise) as illustrated in Katrina van Grouw’s book The Unfeathered Bird:

Yes, all those coils visible in the torso are the trachea, which is many times longer than it needs to be to connect the head to the lungs. Birds-of-paradise do this sort of thing a lot (Clench 1978).

And they are not alone: cranes and others also have elongated and contorted tracheal trajectories. So it’s odd that herons seem to do the opposite.

But the heron is even odder than that. As we have noted before, herons can stretch their necks out to the point where you would scarcely believe the unstretched and stretched animals are the same thing. But they are:

The CT-scanned heron at the top of this post is in a pose intermediate between the two shown here. But since it can adopt the long-necked pose on the right, it’s apparent that the trachea can become long enough to connect the head and lungs in that pose. Which means it must be able to stretch to nearly twice the length we see in the CT scan.

Don’t try this at home, kids!

References

  • Clench, Mary H. 1978. Tracheal elongation in birds-of-paradise. The Condor 80(4):423–430. doi:10.2307/1367193