What specimen is this — the reveal!
May 2, 2013
Yesterday I asked whether anyone could identify this specimen:
There was an interesting range of suggestions, but I suppose no-one will be surprised to hear that Darren Naish was the first to make real progress, saying “Hey, that’s a loooong pelvis… I smell macropod.” From there it was a short leap to William Miller asking “Could it be that wallaby from way back in Things to Make & Do part 3?”
Yes it could, William — you win ten shiny new SV-POW! dollars.
It is indeed Logan the wallaby from waaay back in late 2009. Here’s how I butchered him, and some detail on his feet, and how his skull turned out. Back then I prepped out a forelimb and a hindlimb, the skull and first few cervicals, and the tail (which I don’t think we’ve ever featured here — I should fix that.) When I ran out of time to work on the rest of the specimen, I just dumped it in a plastic tub, added water, and left it for nature to do the work for me. The plan was to fish out the goodies a few months later, but it seems that while my back was turned, three and a half years have passed. I should get on that — if the bones haven’t softened to the point where they’re useless now.
BTW., AnJaCo wins a bonus prize of five SV-POW! dollar for guessing that the specimen was “Sub-adult or juvenile. From the aforementioned disarticulated innominate, and from the dissociated epiphyses of the centra”. Logan was eighteen months old at death, which makes him a sub-adult as Bennett’s wallabies mature at 20-24 months.
Designing book covers in half an hour
January 18, 2013
Matt and I have been sniggering at the Lousy Book Covers tumblr (slogan: “Just because you CAN design your own book cover doesn’t mean you SHOULD”). A couple of evenings ago, he wondered whether we could do better. And whether we could do it in half an hour.
In no time at all, a competition was born. Here are the rules:
- You have 30 minutes total to create the cover from scratch.
- When the time starts, generate a batch of six random titles at the kitt.net Random Book Title Generator.
- Choose the one you like most, and make a cover for it.
- Use your own name as the author.
- You may only use copyright-free or CC BY materials, and be prepared to demonstrate that you have done so.
- The cover must be in the correct aspect ratio for a “B Format” paperback (129 x 198 mm) and in a decent resolution — at least one megapixel.
There are probably better random title generators out there, but we just used the first one we found. It gave Matt these six titles: Silken Magic, The Missing Bridges, Theft of Abyss, The Sorceror’s Slaves, The Year of the Beginning and Cloud in the Petals. And it gave me these: Rough Eyes, The Trembling Spirits, Snow of Eye, The Wind’s Flames, The Names of the Name, and Mists in the Servants. Obviously some of these are completely unusable (“The Mists in the Servants” — I mean to say, what?) but you’re pretty much always going to get at least one that works.
Anyway, here’s what Matt came up with, interpreting his chosen title as non-fiction and sneakily inserting a subtitle:
Pretty sweet work, I think — although Matt was unhappy with the vertical spacing, feeling that the author name was too close to the bottom. The baby-turtle image is by John Winkelman, from flickr, and it’s CC BY. (Matt cut the hand and turtle out so that he could drop the contrast a bit on the background, which accounts for the obvious ‘shoppage around the fingers visible at full res.)
I interpreted mine as a Fantasy novel, and I guess I sort of added a subtitle too, in a way. Here it is:
The background image is cropped and modified from Desert sky scene at dusk by Steve Hillebrand of the U.S. Fish and Wildlife Service, which is public domain. The parts that work well, I think, are the different capitalisation, size and colour of the “the”s and “NAME”s; and the translucent star underneath the title. If I could do it again, I would swap the two dark reds, but there you go.
I ran out of time to do the author name nicely, so it’s pretty blunt. If I’d had more time, I would also have put a small but clear single artifact in the middle of the cover — perhaps a sword or lantern, or maybe something a bit more left-field like a scroll or a leather water bottle. But since I ran out of time, this is how it stays.
(One important lesson I learned is that I need to figure out how the get GIMP on my Mac to recognise more fonts — it has a tiny selection, and all the sans-serif ones look like they’re straight out of a PowerPoint presentation.)
So now we challenge you: what can you come up with thirty minutes total? If you have a go at this challenge, upload your images and post a link in a comment. (You can upload easily at sites like imgur.com if you don’t have an account on flickr or similar.)
Tutorial 20: how to measure necks using Duplo
January 10, 2013
I’ve measured a few necks in my time, including the neck of a baby giraffe. I can tell you from experience that necks are awkward things to measure, even if they have been conveniently divested of their heads and torsos. They have a tendency to curl up, which impedes attempts to find the straight-line length. Even when you manage to hold them straight, you want them maximally compressed end-to-end rather than stretched out, which is hard to achieve without buckling them out of the straight line. And then you need to measure between perpendiculars in a straight line.
Awkward.
Tonight, I needed to measure the mass and length of seven turkey necks. (Never mind why, all will become clear in time.) And I found a way to do it that works much better than anything I’ve done before.
Here’s the equipment:
You will need:
- Kitchen scales (for weighing the necks)
- Small numbered labels (for the sandwich bags that the necks will go into for the freezer once they’ve been measured)
- Pen and paper to take down the measurements
- Translucent ruler
- Saucepan full of turkey necks
- Slightly less than one half of a birthday cake decorated like a map of Middle-earth [optional]
- A Duplo baseboard (double-sized Lego) and about fifteen 4×2 bricks
Use the bricks to build an L-shaped bracket on the board — about half way back, so that can rest your hand in front of it.
Now you can push the neck into the angle of the bracket. By keeping it pressed firmly against the back wall (yellow in my construction), you can keep it straight. I find the best way to get the neck exactly abutting the left (red) wall is to start with the neck in its natural position, with the anterior and posterior ends curving towards you, then sort of unroll it against the back wall, and finally push the posterior end into place with your little finger (see below). There is a satisfying moment– almost a click — as the back end pops into place and the neck slides along a little to right as necessary to accommodate the added length.
Now use another brick (blue in this photo) as a bracket: slide it along the back wall from right to left until it’s solidly abutting the anteriormost vertebra. If you do this right, there is very little travel: the entire series of vertebrae is lined up and solidly abutted, with bone pushing against the left wall and your new brick. I find there’s less than half a millimeter of variation between the length under gentle-but-firm pressure (which is what I measured) and under the very strongest force you can exert without buckling the neck.
Once you have found the blue brick’s correct position, you need to hold it firmly in place and measure its position relative the the left wall. (It doesn’t matter if you let the neck re-curl at this point, so long as the blue brick doesn’t shift.)
You need a translucent ruler so that you can lay it across the neck and see where blue brick falls under the scale. (My ruler’s zero is, rather annoyingly, 5 mm from the end; so I needed to subtract 5 mm from the lengths I measured.)
Finally, I bagged up each neck in its own sandwich bag, ready for the freezer. Each neck is labelled with a number so that when I take it out for dissection, I will be able to relate the measurements and observations that I make back to these initial measurements.
For the record, here are the measurements:
- Neck 1: 154 g, 179.5 mm.
- Neck 2: 122 g, 151 mm.
- Neck 3: 154 g, 199.5 mm.
- Neck 4: 133 g, 162.5 mm.
- Neck 5: 142 g, 169 mm.
- Neck 6: 80 g, 167 mm.
- Neck 7: 70 g, 169 mm.
As expected, there is some correlation between neck mass and length; but not as much as you might expect. Naively (i.e. assuming isometric similarity) mass should be proportional to length cubed, but there is a lot of scatter about that line. I don’t know whether that is due to individual variation, or merely because the various necks — all of them incomplete — are different sections of the full neck. Hopefully I will be able to confirm or rule out that possibility when I’ve dissected down to naked vertebrae.
Things to Make and Do, part 8: baby giraffe neck
March 24, 2011
Back in early Februrary, Darren and I got an email out of the blue from biomechanics wizard and all all-round good guy John Hutchinson, saying that he’d obtained the neck of a baby giraffe — two weeks old at the time of death — and that if we wanted it, it was ours.
Of course, the timing wasn’t great for me — Brontomerus day was coming up fast, and the final publicity arrangements were buzzing around like crazy, so it wasn’t possible to go and fetch the neck right then. But John had an even better proposition: that he could keep the neck frozen, and we could come to the Royal Veterinary College and dissect it on site. As soon as I’d established with Darren that I’d get to be the one to keep the bones when the dissection was done, we enthusiastically agreed, and booked a date with John. [The photo here shows a baby giraffe, not the one that we had -- note that the neck is proportionally much shorter than in an adult.]
And so it was that on Wednesday 9th March, I drove up from Ruardean to Potter’s Bar and picked up Darren and pterosaur-jockey John Conway from the railway station. From there, we found our way to the RVC campus easily enough, with only the statutory minimum number of times getting lost (once).
The bad news was that the neck had already been skinned before it made its way to the RVC. We don’t know why, by whom, or when, and more importantly we don’t know how much of the other soft tissue was removed in the process — for example, the trachea and oesophagus were gone — along with, we assume, the recurrent laryngeal nerve that Matt had asked us to look out for — and we wonder whether our nuchal ligament was complete. (That is the long ligament that runs along the top of the neck and helps to prevent it from sagging.)
But anyway, here is our baby, in left lateral view, as it came out of its plastic sack, measuring a healthy 51 cm in length.
Like so many specimens, at this point it really looks like an undifferentiated blob of gloop. There are a couple of things to look for, though.
On the left of the picture, you’ll see that the terminal 10% or so is well separated from the rest, ahead of of portion of exposed bone. That bone is the anterior margin of the axis (i.e. the second cervical vertebra). The atlas (first cervical) is still encased in soft tissue at this point, but could be moved around fairly freely, including twisting.
On the right, and you’ll probably need to click through to see this, is a strange metal pin, stuck right into the back of C7. This was firmly embedded and we never figured out what it was, or what it was doing there. As you’ll see in the photos below, I’ve allowed it to stay in place, even in the final prepared vertebrae. If anyone knows what it is, do tell!
I took a bunch of photos and measurements before we ploughed in, but I am ashamed to say that I failed to get many, many of the images and numbers that I should have. Even allowing for the fact that the specimen was not intact when we got it, we and particularly I fumbled the ball badly. So much so that I will shortly publish a tutorial on How To Dissect A Neck which will be based primarily on what we failed to do.
I suppose it’s true that we only ever learn from mistakes. The trick is to learn from other people’s, rather than going through the frustrating and expensive process of making your own. Oh well. Next time, for sure.
Here we have John (left) and Darren (right) hard at work teasing away the long epaxial muscles from their fascia.
It was only after that process was complete that we thought to do one of the things we should have done up front — test the range of motion. We put the necks into poses of maximal extension, flexion and lateral deflection. Contrary to what I would have expected, the last of these was significantly more impressive than the other two, and is shown here. You can easily make out the separate extents of vertebrae 2, 3, 4 and 5, and from those see where 1, 6 and 7 are.
(Those are the long epaxial muscles in the background.)
We continued removing muscle and fascia until we had the vertebrae as close to naked as we could manage without risking damage to them, while retaining the integrity of the intervetebral joints — both intercentral and zygapophyseal articulations. One of the big surprises to us was how very flexible and fragile the latter were compared with the former. The membrane that contains the zygapophyseal joint is very thin and would contribute almost no mechanical strength of its own. By contrast, the adjacent centra were bonded very firmly together by extremely tough tissue. There was no trace of a separate cartilage disc between any pair of centra, just this very dense but flexible material which had to be slowly cut away with scalpels before the vertebrae could be be separated.
The exception to this was the atlas-axis joint, which surprised all three of us in how completely different it was to all the others. There was no connective tissue at all between the front of the axis and the back of the atlas — the two bones (or rather their cartilaginous surfaces) were free to move against each other without let or hindrance, as shown here (right anterolateral view with anterior towards the bottom of the picture):
And yet the axis was very firmly attached to the axis: although we couldn’t see any attachment, it wouldn’t come away — not even when a great deal of force was applied. The connection turned out to be between the ventral face of the odontoid process and the dorsal surface of the ventral portion of the atlas. (If you’re not familiar with anterior cervicals, this should become clearer later on when I show you the individual bones.) Suffice it for now to say that the atlas is basically ring-shaped, and that the odontoid process is a chunk of the axis that sticks out the front of that bone and sits within the O of the atlas.
Before we separated the vertebrae, though, we prepared the nuchal ligament out from its surrounding muscle. Here it is, with John and Darren holding its posterior portion up above the vertebrae: you can see that it’s in the form of a sheet rather than, as often envisaged, a cylinder. (It does extend further anteriorly than shown here, but its much less extensive over C2 than it is more posteriorly.)
We did the best we could at detaching this ligament intact so that we could measure how compliant it is. It was difficult to remove without damaging, and much more irregular in shape than we’d expected, so that the anteriormost portion had almost no strength and broke as soon as we exerted any force on it.
We were initially able to remove a portion that measured 45 cm at rest (from a total neck length of 51 cm, remember), but once the thin anterior end had broken off, we were left with 32 cm. We were able, by application of a significant force courtesy of Darren, to extend this to 42 cm but no further. That’s a strain of (42-32)/32 = 0.3125, which is a lot less than I’d been expecting. Alexander (1989:64-65) wrote (in the passage that was my first ever encounter with nuchal ligaments):
I am going to suggest that these necks [i.e. those of sauropods] were supported in the same way as the necks of horses, cattle, and their relatives. These animals have a thick ligament called the ligamentum nuchae running along the backs of their necks (figure 5.5). Unlike most other ligaments it consists mainly of the protein elastin, which has properties very like rubber. It can be stretched to double its initial length without breaking [...] In experiments with deer carcasses, my colleagues and I found that the ligament was 1.4 times its slack length when the head was raised to the position of figure 5.5 [i.e. a typical alert posture], and almost twice its slack length when it was lowered to the position of figure 5.5b [grazing posture]. Notice that the ligament was stretched even when the head was high: I doubt whether a deer can get into a position that allows the ligament to shorten to the point of going slack. If you cut the ligament in a dissection the cut ends spring apart, as if you had cut a stretched rubber band.
So the least stretched life position of the ligament, according to Alexander, is significantly more extended than the most stretching we could achieve. What does this mean? I see four possibilities:
- Alexander was talking a pile of poo. I don’t believe this for a moment, and mention it only for completeness.
- I am talking a pile of poo. I can see why you’d think so, but I know it ain’t so (and Darren and John can verify it).
- The composition of the nuchal ligament changes through ontogeny, becoming more elastic as the animal gets older: we had a baby, and Alexander had adults. I don’t think this is very likely either — I can’t see any reason why juveniles would need less elastic ligaments than adults.
- The composition of the giraffe nuchal ligament is different from that of the deer.
Since I already eliminated the first three options, it won’t come as a great surprise to find that I favour the last one. And this has some interesting implications if it’s true. (Darn, darn, we should have saved a chunk of the ligament and found a way to get it analysed for composition.) If that nuchal ligament of giraffes is largely collagen rather than elastin, then it suggests the possibility of something similar for sauropods, and that would be interesting because the tensile strength of collagen is much greater than that of elastin.
Does anyone know if anyone’s done any work on this?
Well, anyway.
I drew the long straw, and got to bring the remains of the neck home to prepare out as bones. I simmered gently, then removed the cooked flesh, and was astonished to find how much there was, removed from vertebrae that we thought we’d cleaned pretty well at dissection time:
The disappointing part of this is that such large parts of the vertebrae turned out to be cartilage (partially ossified, I guess) and so came away during the simmering: huge chunks at the front and back of each centrum, like a full centimeter at each end, and all of the zygapophyseal articular surfaces. I wish I could have kept them intact … and of course a different preparation method probably would have done. More stupid still, I neglected to get photos of the individual vertebrae before simmering, which would at least have enabled me to show you before-and-after comparisons. Sorry.
Anyway, having peeled off the soft-tissue including cartilage, I re-simmered, re-picked, then bathed in dilute hydrogen peroxide for two days, and dried out the vertebrae in the sun. This is the result — C1-C7 in order, in left lateral view:
Note that the odontoid process of the axis is a separate bone from the rest of the axis — you can see it on the left, between atlas and axis. There was a big chunk of sculpted cartilage joining it to the rest of the atlas, and that’s all gone now, so I am not sure how I am going to join it up — maybe layer on layer of PVA representing the cartilage?
Oh, and notice that the metal pin is still in C7.
In the picture about, I have laid the vertebrae out in such a way that the total neck length (front of C1 to C7) is 51 cm, the same as it was in life. Notice how this leaves huge gaps between the central: for example, as here between C5 and C6:
Needless to say, anyone trying to reconstruct the living animal from the bones alone — from fossils, say — would get a hopelessly wrong neck if they didn’t take the missing cartilage into effect. As we’ve noted before, the same is true of sauropod necks.
But just how informative is a juvenile neck? No doubt, the cartilaginous portions of these vertebrae were proportionally much larger than they would be in an adult, so we do need to be careful about casually extrapolating the huge gaps between ossified centra in the images above into our interpretation of sauropods. For sure, I now need to go through this process with the neck of an adult giraffe — and if anyone happens to acquire one, I would love the opportunity to dissect it, please contact me if this comes up!
But maybe it’s not quite so misleading as it looks — for two reasons. First, nearly all the sauropod specimens we have are from subadults, as shown by lack of fusion between scapula and coracoid in, for example, the Giraffatitan paralectotype HMN SII. So it may be that their vertebrae were also not fully ossified. And second, sauropods are more closely related to birds than to mammals, and in my limited experience bird necks seem to have a larger cartilaginous component than those of mammals.
Well. Draw your own conclusions. But keep ‘em qualitative for now.
Next time, I’ll be presenting a tutorial on how to dissect a neck. But it will be based on what we should have done rather than what we actually did.
What’s that? You want proof, you say? Well, I find your lack of faith disturbing; but since you asked, you got it!
What we have here is the part-way assembled skull of our old friend Veronica, in dorsal view, with anterior to the left. The long pointed bones down there are the nasals: you don’t see their anterior ends in complete skulls because they’re covered by the fused premaxillae. Posterolateral to those are the lacrimals, forming those posterolaterally directed spurs. Between the nasals towards their posterior end is the top of the mesethmoid. Behind the nasals and mesethmoid are the frontals, the largest bones on view here; and behind those are the parietals. Ventral to those superficial bones are the palatines (sticking forward and showing on either side of the nasals), plus the pterygoids, the squamosals, and of course the braincase including the parasphenoid rostrum and fused vomers, but those are all hidden in this dorsal view.
Here’s the whole hill of beans in ventral view: this time you can see the parasphenoid rostrum going down the midline, with the vomers fused onto its anterior end; and the pterygoids attached near the base of this process, and the palatines extending anteriorly from them. In this view, the squamosals are the lateralmost projecting bones. Zoom through to the full-sized images to see the cool pneumatic openings up inside the squamosals and the parts of the braincase that they articulate with.
Still waiting to be attached to the cranium: the quadrates (which go on the lateralmost points of the skull); then the quadratojugal, jugals and maxillae, forming a straight line directed anteromedially from the point of the quadrate; and finally the fused premaxillae which go on the end of the snout and join the nasals medially and the maxillae laterally. Those bones will of course obscure some of what we can see at the current stage of assembly, so I thought it would be useful to show you this intermediate stage.
Since I’m here, I may as well show you how the partially reassembled cranium looks in left lateral view, too:
From here, you can really appreciate the weird shape of the lacrimals, with their ventrally directed processes that I think are going to contact the maxillae once I’ve got them attached.
Finally, those of you who have been wise enough to get hold of some red-cyan anaglyph glasses will be able to appreciate this spectacular 3D view of the skull in ventral view. The rest of you: come on, sort it out: they cost maybe a couple of bucks, and they’ll revolutionise your perception of, well, anaglyphs.
Things to Make and Do, part 6e: gloat your eyes, feast your soul, on my ostrich ethmoid ossification
July 19, 2010
Work continues apace with Veronica, my tame ostrich. (See previous parts one, two, three and four). I’ve been photographing the individual bones of the skull — a skill that’s taken me some time to get good at, and one that I might do a tutorial on some time, to follow up the one on photographing big bones.
Here is a preview of the result of this photography-fest: a multi-view figure of the ethmoid ossification.
The top row shows it in dorsal view; the middle row in left lateral, posterior, right lateral and anterior views; the bottom row in ventral view.
This is a midline bone, or rather complex of bones, that lives between and slightly ahead of the eyeballs, as shown in the photographs of part 6c. The top part is the mesethmoid, which contributes to the roof of the skull between the nasals and ahead of the frontals. Below that is — well, I’m not sure what it’s called. Jaime said in a comment that it’s “a portion of the ossified interorbital septum”, but it’s not like a septum: it’s a hollow capsule with very, very thin walls. Anyone know its proper name?
By the way, I strongly encourage you to click through the image above and see it in its full high-resolution (5943 x 3384) glory. As a taster, here’s a small segment — the rear portion of the dorsal view — in half resolution:
As you can see, that’s some very well textured bone — much more so than is apparent to the naked eye.
It’s been a while since we last caught up with my wallaby, which I am suddenly going to decide to call Logan. When we saw him last, I was concentrating on his feet, although the initial post does also include a photo of the partially prepped skull in right lateral view.
Back in the day — and this was eight months ago, remember — I wrote “I think that [the skull] would benefit from a third simmer-and-pick session before I put [it] out somewhere for invertebrates to deal with.” That’s what I did, but the results were not encouraging. I put the skull (and first three cervical vertebrae, which I’d prepared with it) into a plastic box with air-holes and left it in the woodshed — an approach that’s worked well for Darren Naish many times, and has also served me well regarding that baby rabbit that I keep meaning to show you. But when I went to retrieve Logan’s skull a few days ago, I found that it had gone mouldy!
There should be a picture of Mouldy Logan here, but I stupidly forgot to take one. So instead here is the fifth cervical vertebra of the Erketu ellisoni holotype IGM 100/1803, with its bizarrely sigmoid centrum, from Ksepka and Norell (2006: fig. 5).
Well, anyway – ouch! I didn’t even know bone could go mouldy. And what I didn’t appreciate at that point is that the mould had also made the bone fragile, brittle — crumbly, even. Not good at all. To get rid of the mould, I simmered the skull and vertebrae gently for an hour or so, then cleaned it up with a toothbrush and some washing-up liquid (or “dish soap”, as you wacky colonials apparently call it). It was at this point that the crumbliness became apparent, of course: the respiratory turbinates were completely gone, and the nasals, having come away from the rest of the skull, broke into three pieces each. Also, the dorsal margins of the maxillae and premaxillae, where they abut the nasals, started to crumble. Finally, the bone directly above the foramen magnum whose name I can never remember came away, and a small chunk came away from the bone that that abuts it to the left. It wasn’t pretty.
Anyway, I cleaned the bones as carefully as I could, then let them soak overnight in dilute hydrogen peroxide before carefully rinsing them and leaving them to dry. The result still looks good, but it’s disturbingly fragile. Here it is:
Subadult male Bennett's Wallaby, "Logan": mandible, cranium and fragmented nasals in dorsal view; cervical vertebra 3, axis, odontoid and atlas (top to bottom).
I also prepared a red-cyan anaglyph of these bones, from an aspect slightly anterodorsal of dorsal. Those of you who have not yet obtained red-cyan glasses for viewing these, get your arses in gear — they are really informative.
Finally, here is a close-up of the crumbling nasal region, and the remaining pieces of the nasal bones. You can see that the bone has lost integrity.
(Those two fragments at the bottom of the picture are, I think, from the dorsal border of the right maxilla.)
And now, gentle reader, I come to you for advice. What can I do to strengthen poor Logan’s skull? I guess there must be some kind of commercially available compound that I can soak it in or paint on to it to consolidate the friable bone? Help me out, please. I don’t want to lose Logan.
And by the way …
I realise that SV-POW! has been heavy on these extant-animal-skeleton posts recently, and correspondingly light on actual, you know, sauropod vertebrae. I hope no-one feels too short-changed: I’ve been assuming that among that constituency that appreciates sauropod vertebrae, there’s a corresponding liking for ostrich and wallaby skulls. Do let me know if it ain’t so (or indeed if it is).
Cleaning and bleaching is complete! Here are all the bones of Veronica’s skull [see earlier part one, part two and part three], laid out as they were in life (though of course much more widely separated), all in dorsal view:
On the left, we have the bones of the lower jaw, palate and braincase, with the first three and a half vertebrae at the bottom. At the top is the mandible, which is intact on the left side but has separate articular, angular and surangular on the right; between the mandibles are the hyoid bones, of which one of the cartilaginous extensions has survived. Behind those on the midline are the fused vomers, parasphenoid rostrum and braincase, all fused together. Alongside this element are the palatines and pterygoids, and to the right of those are the midline supporting cartilage and mesethesmoid ossification. Behind the braincase are the first three and half vertebrae of the neck.
On the right, we have the superficial bones. Reading down from top to bottom of the midline, we have the premaxilla, nasals, lacrimals, frontals, parietals, and (out towards the sides) squamosals; from top to bottom down the sides we have the premaxilla (again), maxillae (the left one broken in two), the jugals and quadratojugals (which are still fused together on the right) and finally the quadrates.
That’s everything! My next tasks are:
- Repair the three broken bones: left maxilla, left posterolateral process of the premaxilla, and left lacrymal.
- Photograph every individual bone from all six cardinal directions and maybe some interesting oblique angles.
- Put the skull back together.
- Photograph the entire skull, including 3d anaglyphs.
Then I think I’ll be done.
Special bonus encouragement
A few articles back, Zach Miller commented:
You lucky bastard! First a monitor lizard, now this? I’ve really GOT to get some kind of deal going with my local zoo. :-)
Lucky? Nothing to do with it! One of the points I keep meaning to make in the Things To Make And Do series is how very much this is something anyone can do. Well, OK, I admit I was super-lucky to score the monitor lizard; but I got the pig’s head by walking into a butcher’s shop and saying “One of your finest pig’s heads, please, my stout yeoman!”. I got Veronica by googling for “ostrich farm” and emailing the ones in the UK asking whether any of them had any heads to spare. I urge you, and anyone else who loves anatomy, to do the same.
Anyone can do this! You don’t need qualifications, or even experience; this is how you get experience. Seriously, I’ve learned ten times more about dinosaur skulls in the last week from playing with Veronica than I did in the last five years of feeling guilty that I never read any head-related papers.
After the third simmering, Veronica the Ostrich Head started to come apart beautifully — more so than she should have done in one or two places, as it became apparent that her skull, as well as being incompletely fused due to presumed subadult age at time of death, was slightly damaged. Still, I’ve been able to tease the bones apart nicely, remove pretty much all the remaining soft tissue, and figure out where most bits go, well enough that I think I’ll be able to put her back together once everything’s been cleaned.
[Anyone who's not yet read parts one and two of this ostrich-head series should probably do so before going on to this one -- apart from anything else, the pictures will make more sense that way.]
Here’s my girl as she emerged from the pot (cranium only — the mandible was separate by this point). What may not be apparent here is just how fragile she was by this stage: I had to hold her snout as well as the main part of the skull to prevent it from falling off. You can see that it’s skewed a little sideways, rotating clockwise with respect to the rest of the skull so that the posterodorsally oriented midline “tongue” of bone is off to the left (our right), and lies alongside the central bulging bone rather than overlying it as in earlier stages.
The squamosals are still in place at the sides of the back of the skull, but they came away very easily, and cleaned up nicely.
I carefully removed the snout, and was astounded to see how very thin the bones that connect it to the rest of the skull laterally are:
The midline bone here apparently is the fused ascending processes of the premaxillae, despite my having said last time that it probably wasn’t — thanks to Nick Gardner for putting me straight. but what are the posterolaterally directed spines? Can they also be processes of the premaxillae? Or are they the maxillae? I think the former: read on.
It’s hard to tell in part, of course, because of the horny beak which obscures whatever sutures might be up there at the front of the skull. I don’t want to remove that, partly for fear of causing damage to the bones but mostly just because it’s nice to keep. What I’d not appreciated until I started this exercise is that there’s no hard demarcation between beak and soft-tissue, but they grade into each other so that the posteriormost preserved parts of the beak are not horny at all, but rubbery — even stretchy. It’s hard to know how much of this to remove. If there’s a Standard Operating Procedure, I don’t know it — anyone? Maybe I’ll leave the snout in a bug-box and let the dermestids decide. (Let the Dermestids Decide would be a good title for a debut novel, and its Oscar-winning movie adaptation.)
(Of course this continuous gradation between tissue types is familiar to all of us who’ve ever tried to remove the cartilage from a skeleton: in some cases, like the cartilage caps on long bones, there’s clear bone and clear cartilage, but in other cases it’s not so well-defined. Think, for example, of the partially ossified but partially cartilaginous breastbone of a chicken — take a look the next time you have a Sunday roast. This is a real problem in cleaning skeletons.)
Once I’d removed the snout, here’s what remained:
On the midline, half way along the remaining skull (i.e. anteromedial of the orbits) is a very fragile self-contained bony capsule which seems to be full of some kind of soft tissue — maybe fat. It’s not easy to make out its boundaries in this photo, so here is another that I took of the skull after lifting the capsule out — you can see it in the background. Does anyone know what the capsule is? My feeble bird-skull literature isn’t telling me anything about this.
With this capsule gone, it was with me the work of a moment to lift out the two big, spongy, soft-tissue masses from in front of the orbits, which you’ll remember I decided not to attempt last time. A very good decision that proved. Having removed them, I found a neat cartilaginous midline structure which I’d like to preserve for the final reconstruction of the skull, but which is already changing shape dramatically as it dries up so I fear I’m going to have to let it go. Anyway, the bony structure of the remainder of the skull is now much more apparent:
I am guessing that the anteriormost lateral bones are the maxillae, which are a super-weird shape. As you can see, the left bone is broken: its anterior portion is missing. Happily, I have this bit, and it’s a perfect fit for the posterior part, so a bit of superglue should fix this problem — but it does emphasise just how insanely delicate many of the skull bones are.
I think the “wing” bones projecting laterally from near the back of the skull must be quadrates: if so, then the bones that project anteriorly from them are quadratojugals, which shade into straight, elongate jugals (you can see the junction in the near side of the photo above) and then connect with the maxillae.
The midline bone, which is surprisingly robust, seems to be made up of fused vomers or somethingat the front, and the parasphenoid rostrum to the rear [thanks to Nick Gardner for this and other corrections]. They’re hard to see in this photo, but there’s also a pair of oddly shaped more-or-less horizontal plates ventrolateral to this midline bone (I think they must be the palatinespterygoids) and two longer, narrower bones anterior to these (which might be the vomers, in which case the fused midline bones are something else? are the palatines).
Once I’d removed all these, I was left with a solid braincase fused together with that midline bone that might be vomersmade up of the parasphenoid rostrum and vomers. And that, with surprising suddenness, was that.
So here is the complete set of skull bones, laid out in something resembling their order in life: top of the skull at the top of the picture, facing left, with vertebrae to their right; bottom half of the skull (mandible first, then palate) at the bottom of the picture, also facing left. (Sorry that the contrast is not great: the sun was almost down by the time I took this photo):
When I looked at this, I was reminded of a passage in one of Dave Barry’s old columns, ‘Mister Mediocre’ Restaurants, in which he proposed some surefire business ideas, including a place where you could have your non-functional gadgets permanently destroyed:
The idea there was that consumers would bring their broken electronic devices, such as television sets and VCR’s, to the destruction centers, where trained personnel would whack them (the devices) with sledgehammers. With their devices thus permanently destroyed, consumers would then be free to go out and buy new devices, rather than have to fritter away years of their lives trying to have the old ones repaired at so-called factory service centers, which in fact consist of two men named Lester poking at the insides of broken electronic devices with cheap cigars and going, Lookit all them WIRES in there!
Similarly, I found myself thinking: lookit all them BONES in there!
Happily, help was on the way: Nick Gardner sent me a copy of Maxwell 2009, which has a few useful figures, and from these I was able to take pretty good guesses on the identities of more of the bones. (That’s why I’ve included more guesswork above than in previous articles in this series.) So I leave you with an annotated version of the photo above, with my best guess at identifying the bones. PLEASE MAKE CORRECTIONS IN THE COMMENTS — I will make up a revised version of this annotated photo once they’re all in. For for now, here it is Here is the initial version, which Nick critiqued in the comments:
And here is the corrected version, so far at least:
Now let’s get those corrections going!
References
- Maxwell, Erin E. 2009. Comparative ossification and development of the skull in palaeognathous birds (Aves: Palaeognathae). Zoological Journal of the Linnean Society 156:184-200.
Yesterday, I followed up Veronica‘s second simmering by taking more flesh off the bones, and in doing this I stared to take apart the bones that constitute the skull. I assume you’re all keen to see pictures, so here she is upside down and in right posteroventrolateral view:
The interesting thing here is that I have removed all the cartilaginous hyoid apparatus, as I suspected last time that I’d end up doing, only to find that part of that apparatus was bony after all: the pair of slender anteromedially oriented bones that you see at the top of the photo. Here they seem to be directly somewhat ventrally from back to front (i.e. upwards in the photo, since the head is upside down), but comparing with the earlier lateral-view photos of the intact and skinned head, I think that this is post-mortem displacement caused by cooking, and that in life they were more or less in the horizontal plane.
When I removed these bones, I found that their proximal ends were not articulated with other bones, but that they were extended by cartilage rods that continued posteriorly and seem to have been anchored only in soft tissue. Is that weird? Or should I have expected it? It frightens me sometimes how little I know about heads.
You’ll also notice from this photo that I’ve now removed the anterior part of the neck that was attached to the head: as a result, I have a nice bonus set of atlas/axis complex, C3 and the front half of C4 (all pictured below).
Anyway, it was easy to tease away the soft tissue enclosing the mandibular joint and then to remove the bony mandible completely. This they now do. The mandible itself is amazingly lighlty built — see the photo at the end of this post, and more to the point the ones in the next post which I’ve not written yet. Here’s the cranium in ventral view once the mandible was gone and I’d removed some of the skin from the roof of the mouth:
I’m not even going to expose myself to ridicule by attempting to identify any of the bones of the palate — that’s an area that I don’t know at all beyond the fact that there are things called “vomers”, which would make a good name for a race of bad guys in Buffy. Clearly I need to get hold of a general bird-skull osteology. Can anyone recommend anything? Better still, can anyone offer a PDF?
Instead, let’s flip Veronica over and take a look at her top. After the second simmering, the bones of her skull were very easy to disarticulate, so that’s what I’ve started to do here:
Those two main bones forming the crown of the skull are the frontals. I assume those are elongate nasals in front of them, reaching down to the lateral edges of the snout (with the maxillae not visible in this view), but I don’t know what that tongue of bone on the midline is, between them: surely it’s too far back to be fused premaxillae? Someone help me out here.
Anyway, the frontals lifted away cleanly and easily (the right frontal bringing its ?nasal with it, being still slightly attached). This reveals how huge the eyeballs are (the big, black globes) and how relatively feeble the brain is (the pale brownish yellow lump between them):
It was easy enough to remove and discard the eyeballs and brain, and some surrounding gloop. The parietal bones that form the back of the skull also came away easily. At this stage I could have continued to tear the skull down but there are some very delicate bones along the midline and I thought it wiser to simmer again before tackling those. So here is Veronica, as she was just before going into the pot for the third time, in right dorsolateral view:
It’s easy to make out the three cavities where the eyeballs and brain were. There’s still a big mass of soft tissue in the middle of the skull, ahead of the eyes and behind the beak, but there’s no safe way to get at it until I’ve removed more of the bones — and those of the snout are very, very delicate.
Finally, here are the bones that I’ve removed from the main cranium (i.e. to get it into the state seen in the previous picture):
Top left (and facing left) is the mandible in dorsal view, and inside it the pair of hyoid bones, oriented as in life. To the right of those are the ?nasals, then the frontals, then the parietals; outside the frontals are the ?lacrimals that I noted in the first post were coming away from their position in front of the orbit.
The bottom row is of course the vertebrae: atlas in posterior view, and axis, C3 and partial C4 in dorsal view, all facing to the left.
That’s all for now. More to come.
