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.
Things to Make and Do, part 6: fun with ostrich heads
June 23, 2010
Please welcome my new best friend, Veronica the ostrich. Well, Veronica the ostrich head, if you want to be picky. She arrived yesterday morning, courtesy of the good folks at Ostrichfayre, very well packaged and still frozen and with a convenient little chunk of distal neck still attached. Here I am with Veronica, having made my way through the packaging:
And here is Veronica herself, in left lateral view, measuring a healthy 24 cm (including that stump of neck, of course, so the prepped skull will be rather shorter):
Yes, of course I only love Veronica for her skull. The soft-tissue is probably fascinating, too, but I don’t have the time (or the expertise really) to do a proper dissection, so it’s all about getting her naked as quickly as possible.
I started out, as usual, with a couple of hours of gentle simmering to soften all the gloop. I used the three standard pieces of equipment: a large pot, an easily cleaned ceramic hob, and a very tolerant wife. Here she is (Veronica, I mean), cooking up nicely:
Once she’d cooled down, it was gratifyingly easy to peel off the skin:
One thing I’d not appreciated about ostriches before I started playing with Veronica is how tiny their beaks are. Most of the snout is not covered by beak, and the lower jaw in particular has only a few centimeters of keratinous covering. You can see this more clearly in ventral view:
Here you can see the very slender mandibular bones running along the lateral edges of the lower jaw, with a thin sheet of muscle stretched between them, and that tiny beak only up on the tip of the jaw.
I also noticed that the trachea seems to be positioned asymmetrically, on the right side of the animal: I don’t know whether this was its permanent position in life, or whether it shifted around and simply happened to get cooked into this position.
For the next step, I carefully removed most of that muscular sheet and the trachea (and some of the neck musculature):
Now you can see the cartilaginous hyoid apparatus that anchors the tongue (that anchor-shaped thing). This is very fragile, and I am frankly not at all optimistic about its chances of making it through the cleaning process. I’m likely to end up with only the actual bones, so enjoy the hyoid while you can. (I similarly lost all the hyoid junk from my monitor lizard. Bummer. I must remember to show you more of Charlie’s cleaned bones some time.)
I leave you with Veronica’s peeled head in dorsal view:
You can see that there’s more beak on the upper jaw than on the lower.
This kind of photograph is invaluable when it comes to putting the bones together at the end of the cleaning process. You can see here that the small bones ahead of the orbits (lacrimals?) are pulling away from the main skull bones. At some stage they’re likely to come away completely, and it’s photos like this one that will show me where to reattach them.
There is a lot of cartilage on this skull, which is likely going to be painful to remove without damaging the bones. I gave Veronica another bath last night, and I’ll probably start trimming the softened cartilage away this evening.
Further bulletins:
- Veronica the ostrich head starts to come to pieces
- Fragments of ostrich skull
- Veronica the ostrich skull, laid bare
- Gloat your eyes, feast your soul, on my ostrich ethmoid ossification
- My dumb observation of the day is that in dorsal view, a partly-assembled ostrich skull looks kind of like a chasmosaurine
Things to Make and Do, part 5: anaglyphs (red-and-cyan 3D images)
January 31, 2010
I hope you have a pair of 3D glasses. If you do, then check this baby out:
Brachiosauridae incertae sedis NHM R5937, "The Archbishop", damaged cervical vertebra S in right posterolateral view; red-cyan 3D anaglyph. This image and others of the same specimen copyright the NHM since it's their specimen.
(This is of course the same vertebra that we last saw in a multi-view composite figure at the end of the Brachiosaurus coracoid post.)
I’ve started to get into the habit recently of photographing some specimens from two slightly different angles: I couldn’t tell you exactly how much rotation I use, but I would guess it’s something like three to five degrees. That’s because I’ve found that flipping back and forth between the two images can give a useful sense of depth. If you don’t believe me, here are two not-quite-identical photos of the Archbishop’s Cervical S: open each of them in a tab, then flick back and forth between them:
Cervical S, first image
Cervical S, second image
It had occurred to me a while back that, just for fun, it would be interesting to composite them into a red-cyan 3D image. But I was prodded into action by two things. First, the free Lego marketing magazine that my boys get sent every month arrived, and with it a freebie pair of cheap cardboard red-cyan glasses. And second, Matt published a steropair of moon images on his blog. Matt’s friend Jarrod is a professional digital effects artist — in fact he’s won Emmies for stuff like blowing up Los Angeles for 24 — and threw together an anaglyph from the moon pictures. I got instructions from Jarrod on how to do this, and was gratified how easy it was. Here you go:
- Open the two photos as two layers of a single image.
- Using the Colour Levels dialogue, turn the red channel of one of the photos all the way down to zero (so that it appears in shades of cyan)
- Using the same dialogue, turn both the blue and green channels of the other photo down to zero (so that it appears in shades of red)
- Change the Layer Mode of the top layer to Brighten Only
That’s it, you’re done! Save the resulting composite image as a JPEG and upload it to your sauropod-vertebra blog. Jarrod uses PhotoShop; I use the Gimp, which is a free more-or-less equivalent program — the same technique works fine with both.
If I was pleasantly surprised at how simple the technique is, I was astounded at the quality of the result. I’d expected all the colour of the image to be gone, and to see a vague monochrome haze. Instead, I saw rock-solid 3D in full colour — truly informative images that convey the morphology of complex bones far better than any published figure I’ve ever seen. Seriously, go get your red-cyan glasses, you won’t regret it.
Here is another anaglyph of the same vertebra, in posterior view close-up, showing in detail what looks suspiciously like a hyposphene below and between the postzygs. (If this is indeed a hypophene, then I believe it’s unique among sauropods.)
Cervical S, posterior view in close-up, showing possible hyposphene.
Journals have occasionally published stereopair images of palaeo specimens: small images a couple of inches wide, next to each other, which you can supposedly see as a single 3D image if you cross your eyes in just the right light provided the wind is from the southeast — personally, I have never been able to see these things, thought Matt can. But these big, full-colour 3d images are orders of magnitude more information.
I’ve never seen one in a journal, in part of course because colour printing is such an insanely expensive luxury. But as Matt says, we all live in the future now, and I hope that’s about to change. I will be sending the Archbishop description, when it’s done, to PLoS ONE, which because of its electronic-only format can include any number of full-colour figures at no cost. I plan to send a few anaglyphs among the more conventional figures. Fingers crossed that they make it into the published version — I guess if I get a traditionalist reviewer, he might think these are frivolous and demand that I remove them. But they are not frivolous: they may be the most informative figures I have ever prepared.
Finally, I leave you with our old friend the pig skull, from all the way back in Things To Make And Do part 1 — but this time in glorious 3D!
Domestic pig skull in left anterodorsolateral view (3d anaglyph).
Things to Make and Do, part 4: brachiosaurid cervical
December 29, 2009
Yes, you too can have your very own brachiosaurid cervical! Specifically, “Cervical P” of the as-yet unnamed brachiosaur NHM R5937, informally known as “The Archbishop”. Here is is!
The Archbishop, Cervical P, paper model in left posterodorsolateral view.
(All images of the vertebra are copyright the NHM.)
All you need is scissors, glue, and this handy cut-out-and-keep schematic. You’ll want to click through to the full-resolution version (which if I say it myself is a thing of some beauty.)
Print this out, then cut around the black lines to make the template:
Then fold downwards along all the grey lines:
Now, just glue the tabs, fold the lines at right angles, and stick the box together.
The very last tab you glue will be the most difficult to get right, because you won’t be able to press the two parts together once the box is closed. So make sure that you glue the long side of the blank base last, as it doesn’t matter so much if that’s not don’t cleanly.
And there is the final result, this time in the opposite view:
The Archbishop, Cervical P, paper model in right anterodorsolateral view.
And that’s all there is to it!
Things to Make and Do, part 3b: Wallaby feet
November 6, 2009
I’m following up immediately on my last post because I am having so much fun with my wallaby carcass. As you’ll recall, I was lucky enough to score a subadult male wallaby from a local farm park. Today, we’re going to look at its feet.
Wallabies are macropods; together with their close relatives the kangaroos and Wallaroos, they make up the genus Macropus, literally “bigfoot”. So wallabies got there long before cryptic North American anthropoids. And indeed their feet are big. Here are those feet, in dorsal view, from before I started doing unspeakable things to my specimen:
Bennett's wallaby, hind feet in dorsal view
From here they look pretty weird, but it’s only when we go round the back that we really see how odd they are. Same feet in ventral view:
Bennett's wallaby, hind feet in ventral view
There are (at least) three things to notice here: first just that the feet are very long; second, the thick, scaly pad that runs all the way up to the heel; and third, the bizarre arrangement of toes. At first glance, it seems that there is one main toe and a smaller one each side, but if you look more closely you’ll see that the medial “toe” is really two tiny toes closely appressed, so that they function as a single toe. This condition is known as syndactyly, Darren tells me. Also from Darren: it’s digit I that is missing in macropods, so the tiny-toe pair are digits II and III, the main toe is IV and the lateral one is V.
(By the way, seeing my patio in these photos reminds me of something I forgot to mention in the previous post: it’s surprisingly difficult to wash wallaby blood off paving slabs. Remember that, kids, it’ll be on the test.)
Regular readers will remember from last time that I planned to prepare the skull and left fore- and hindlimbs by simmering and dissection, and let nature deal with the rest of the elements. You’ve already seen the skull, so here goes with that foot.
After an initial simmer, I was able to skin the left pes, so here it is at that stage, in medial view:
Bennett's Wallaby, left pes in medial view, skinned and simmered
From this angle, you can clearly see the absurdly thin second metatarsal (MT II) that supports the innermost of those two tiny digits. MT III is just as long and thin, but is fused proximally to the much larger MT IV, as we shall see below. The simmering has resulted in the more distal phalanges breaking away from their more proximal brethren, and being pulled downwards and beneath them. This is most apparent with the tiny digits, whose supporting phalanges are clearly visible poking out above the claws. So the large lump of what looks like cartilage at top right is actually phalanx IV-I, with IV-II and IV-III (the ungual) beneath it. Also note the significant amount of resilient tissue below the metatarsals. I’ve cut most of it away, but you can get a good idea from the bits that are still attached distally.
Here is the metatarsus in ventral view after I had removed the phalanges:
Bennett's Wallaby, metatarsus in ventral view, skinned and simmered
Here you can clearly see the syndactyly (in those two closely appressed thin metatarsals II and III at the top of the picture) and the very sculpted distal ends of the larger metatarsals IV and V.
Now let’s skip straight to to the completed stripped-down pes, now in dorsal view:
Bennett's wallaby, left pes in dorsal view, disarticulated and cleaned skeleton; ungual sheaths removed from bony cores.
It’s interesting that the phalangeal formula is so uniform: 0-3-3-3-3. That is, all four digits have two normal phalanges and an ungual. But the differences in proportions between them are quite something.
This is our first look at the tarsals — those seven bones on the left of the picture, before we get to the metatarsals. The three big ones fit together very nicely. At the back you see the calcaneum, where the achilles tendon attaches; next is the astragalus, which sits on top of the calcaneum and where the distal end of the tibia articulates. Next up is a bone whose name I don’t know, being pretty darned ignorant of ankles — might it be the cuboid? Anyway, even after cleaning and cartilage-removal , this articulates very nicely indeed with both the calcaneum and MT IV.
Medial to these (i.e. below them in the picture) are four much smaller tarsal bones whose identity I can’t even guess at. It’s not clear to me how they articulate with the big tarsals — they were all pretty solidly embedded in cartilage and gloop and I fear that they’re not going to fit neatly whatever I do. Hints will be welcome.
One big surprise was the small bones between the metatarsals and their corresponding phalanges: one each at the ends of MT II and MT III, and two each at the ends of MT IV and MT V. Because the proximal phalanges articulate so nicely with their metatarsals, it’s clear that these small bones were not positioned between them in life, but rather floated above them — rather as your kneecap, or patella, floats above your femur-tibia joint. They are sesamoids. Does anyone know whether this sesamoid formula of 0-1-1-2-2 is common? Seems a bit weird to me.
Finally, I leave you with the entire left hindlimb: foot as in the previous picture, surmounted by the tibia and fibula, then by the femur, all in anterior view. Just to the left of the femur-tibia joint is a small bone which I assume is the patella.
Bennett's wallaby, disarticulated left hind limb in dorsal view
Special bonus wallaby limb: over there on the right is the left forelimb. As you can see, I’ve done the easy part (scapula, humerus, ulna and radius) but I still have to dissect out the bones from the wrist and hand — a picky, tedious job that to be frank I am not looking forward to. The feet are much more exciting than the hands.
That’s all for today. On Sunday evening I am off to London to spend a whole week in the company of the Archbishop. The plan is to spend Monday to Wednesday taking final publication-quality photos (I finally have a proper tripod) and digging out field photos and suchlike from the museum archives, then take Cervical U to be CT-scanned at the Royal Veterinary College, courtesy of theropod hindlimb mechanics guru John Hutchinson. Friday is emergency backup in case something crops up to delay the scanning, and also gives me a chance to retake any photos that didn’t come out as required. The plan is that this visit should give me everything I need (pictures, measurements, observations, historical documents) to finish up the long-overdue Archbishop description. Fingers crossed.
I leave you with a puzzle. This is the jacket that I have designated “Lump Z”:
Brachiosauridae indet. BMNH R5937, "The Archbishop". Unidentified elements "Lump Z". Image copyright the NHM, since it's their material.
Can anyone offer a guess as to what this is, and which way up it should be? It’s a jacket that was opened years ago — before I was involved with the specimen — but never fully prepared. Matt and I have discussed it a little, but I don’t want to prejudice anyone with our guesswork, so I leave the floor open. What is it?
SV-POW! Dollars are at stake!
Things to Make and Do, part 3: Butchering a Wallaby
November 3, 2009
This is part 3 of an emerging and occasional SV-POW! series: part 1 was the pig skull, and part 2 was the lizard feet (though not advertised as such because I couldn’t resist the sauropod pun).
Bennett's wallaby, right lateral view
Today, we’re going to be taking a wallaby apart. Specifically, a Bennett’s wallaby, the larger of the two subspecies of the red-necked wallaby Macropus rufogriseus. I was delighted (though of course also saddened) to get a call on Saturday afternoon from the very same mini-zoo that had given me Charlie the monitor — Dick Whittington Farm Park in Longhope, Gloucestershire. They have a small group of seven wallabies sharing a paddock with goats, and one had died — most likely from being butted by one of the goats, although there were no external signs of injury.
This is going to be the largest animal I’ve prepared the skeleton out of — I measured it at 123 cm from snout to tail and 10.5 kg total weight, which compares with 75 cm and 12 kg for the badger, 100 cm and 5.2 kg for the fox and 111 cm and 3.4 kg for the monitor. Yes, the badger was heavier, but the awkward shape of the wallaby makes it all-round “bigger” and harder to deal with. Both the badger and the fox would, just, fit into large plastic toy-boxes which I buried and will exhume after a suitable time has passed, but that wasn’t going to work for the wallaby. I needed to take that baby apart:
Bennett's wallaby, right ventrolateral view into guts
I was pleasantly surprised at what good condition the guts were in (compared with the horrible state of Charlie innards) — nice and fresh. If I’d had time, I’d have attempted to learn something from a proper dissection, but as I was pushed for time (trying to get this done in my lunch break) I had to push on. I discarded the guts and started to carve up the remainder.
Bennett's wallaby in posteroventral view. right leg removed; Homo sapiens for scale
The knife is a Norwegian fisherman’s knife — very sharp, and short enough to be easy to wield. It’s perfect for dismembering a carcass this size, even though previously I’ve only used it for slicing sushi rolls. It was a Christmas present from my employer, Index Data, a few years ago.
My plan was to carefully divide the animal into seven portions (head, torso, tail and four legs), remove as much skin and muscle as I could without risking damage to the bone, and to process the parts separately.
Bennett's wallaby, in kit form, mostly dorsal view but with the head and torso in left lateral. WARNING: GRAPHIC CONTENT
After some thought, I decided to prepare the skull and the left fore- and hind-limb by boiling, and to bury the rest in the box. Here are the relevant divisions:
Bennet's wallaby not looking at all healthy. Top: torso, tail and right fore- and hindlimbs, awaiting burial. Bottom left: head, left fore- and hindlimbs, awaiting cooking. Bottom right: bag full of discarded soft-tissue
Then I put the pot through an hour’s simmering, peeled the skin off the skull and feet, and removed what meat I could; then I simmered a second time and removed more meat. By this stage, I was able to remove the three most anterior cervicals, which had been attached to the back of the skull — but they are still so covered with attached flesh that they’re not much use yet. Here’s how the simmered material is looking:
Bennett's wallaby: skull, anterior cervical vertebrae and left hind-limb long bones
And here is the skull as it looks now, after a little more flesh-picking (but not nearly enough):
Bennett's wallaby, partially prepared skull in right lateral view
I think that it (and the other boiled bones pictures above) would benefit from a third simmer-and-pick session before I put them out somewhere for invertebrates to deal with. While that’s going on, I’ll prep out the foot and the forelimb, which have also been boiled twice but phalanges are a right nasty piece of work.
And then I have to decide what to do with my big yellow box that has the rest of the bits in. Plan A is still burying, but it is kind of tempting to simmer these parts, too, and get the whole thing completed much more quickly.
On the other hand, now is not a good time for such an effort: I will be away from home all week on a mission of utmost importance, and of great relevance to this blog. Details to follow!
Finally, I leave you with your weekly sauropod-vertebra goodness!
Giraffatitan brancai paralectotype HMN SI, cervical vertebrae 2 and 3 in right lateral view, attempting to do DinoMorph
Well, not really really.
Appendicular skeleton of savannah monitor lizard Varanus exanthematicus, "Charlie", in dorsal view.
What we have here is of course the bones of all four feet of a lizard (plus the limb bones): “sauropod” means “lizard foot”, so lizard-foot skeletons are sauropod skeletons — right?
(Note that the hind limbs are arranged in a weird posture here, with the knees bent forward. Also that the left pes is missing one digit — possibly IV — which was presumably lost some time ago and healed.)
These are the bones of “Charlie”, a mature savannah monitor lizard Varanus exanthematicus, estimated as fourteen or fifteen years old at the time of death. I have his whole skeleton — cranial, axial and limb-girdles — in various states of preparation, and no doubt they will all appear here sooner or later. I was fortunate enough to encounter Charlie in the reptile house of a local kids’ activity centre with the boys, and he was not in a good way. Luckily, his keepers happened to come in as I was looking at him, we got talking, and I popped the question as tactfully as I could — would it be OK to take his body away when the sad day comes?
The sad day came, and I found a message on my answering machine. For one reason and another, it was a couple of days before I was able to drive out and pick up his mortal remains, but it was a proud day when I brought him home:
Savannah monitor lizard Varanus exanthematicus, "Charlie", recently expired, in left dorsolateral view. Scale bar for, uh, scale.
Charlie was a good-sized beast: 111 cm in length from snout to tail, and massing 3.4 kg. I tell you, it was quite a challenge getting him into that pot that you see top right.
Savannah monitor lizard Varanus exanthematicus, "Charlie", recently expired, in right anterodorsolateral view. Juvenile Homo sapiens "Jonno Taylor" for scale.
To prepare Charlie for the pan, I had to remove his tail — much, much harder than I’d been prepared for, as it was so difficult to locate the sacrocaudal intervertebral joint — and gut him. Unfortunately, by the time I opened him up, internal decomposition had set in, and he was not in a pleasant state:
Savannah monitor lizard Varanus exanthematicus, "Charlie", recently expired, in the unpopular right posteroventrolateral view.
(I have much more disgusting photos than this one, but it wouldn’t be tasteful to show them.) Anyway, I abandoned my initial plan of dissecting the organs out, and basically just removed and discarded them. I’ve actually had shamefully little experience with dead animals, so I don’t know how much the horrible state of Charlie’s guts is due to his final illness and how much to post-mortem decomposition.
Once I’d managed — just — to get him into the pot, Charlie was lightly simmered for a couple of hours (to Fiona’s delight), then dismembered, and the individual parts reboiled before I started picking the bones out of the various parts. There’s more to say, but that will have to wait for another time.
Sauropod Vertebra Picture of the Week 