Sculpey allosaur claws

A few weeks ago I threw this picture into the “Night at the Museum” post and promised to say more later. Later is now.

I started sculpting dinosaur claws because of the coincidental arrival of two things in my life. One was a cast of OMNH 780, the horrifically awesome thumb claw of Jurassic megapredator Saurophaganax maximus, which I blogged about here. (If you’re curious, I’m using it to amaze people at public talks, so it is serving a semi-legit educational purpose.)

The other is this video of Adam Savage’s TED talk on how he got into sculpting two very different birds. I’ve watched it about a zillion times and shown it to loads of friends, because Savage so nicely captures what it’s like to be obsessed by interesting things. We have different objects of desire, and, okay, I don’t have 20 gigs of photos of anything, but when I’m having a lousy day, watching that video reminds me why I do what I do. You should blow off the rest of this post and go watch it right now.

Back so soon? So, I am a little obsessed with theropod claws right now (aesthetically and fanboyishly, not scientifically), and I thought it would be cool to try my hand at making them. Also, I’ve been wanting to do some molding and casting, and I wanted to be able to practice on cool stuff without having any ethical concerns about trading in fossils or replicating someone else’s specimen. More on the molding and casting in a future post.

A final boring note before the actual instructions: I have no idea what I’m doing. Those two claws in the photo above? The little one on the right is the first thing I’ve sculpted out of anything more serious than Play-Doh, and the big one on the left–the subject of this post–is the second. If I can do this, you can do this.

On to the  how.

1 - raw sculpey

Sculpey isn’t really clay in the traditional sense. It’s slightly oily plastic that polymerizes when baked. When it first comes out of the package, it’s surprisingly brittle and crumbly. You have to knead it for a while before you can do anything useful with it.

2 - kneaded sculpey

Here’s a lump after some kneading. My work surface here is a dinner plate covered with aluminum foil.

3 - rough sculpting with fingers

At the local hobby store you can buy a set of clay sculpting tools, in plastic for about five bucks or in wood for up to thirty. But unless you’re a professional sculptor you can skip all that folderol and just use your fingers and crap you find around the house.

The main thing I learned during this stage? You can achieve just about any shape you want, depending on how much time you’re willing to invest. I worked iteratively, smoothing and resmoothing and smoothing some more.

4 - sculpting with popsicle sticks

Cheap tools in action: using popsicle sticks to smooth the edges of the claw. You can get a bag of 100 of these suckers at the dollar store. If you don’t already have a decent pair of wire cutters, you can get them at the dollar store, too, and you can use the wire cutters to cut all kinds of edges into the popsicle sticks. So that’s like 100 clay tools for a buck or two.

If it seems like I’m hating on fancy clay tools, it’s because IME real artists just get on with making art and don’t get too precious about it. Here’s Zak Smith on painting (warning–nothing bad in that post, but there is some NSFW stuff elsewhere on that site):

the process is as follows:  I take a very small paint brush with wet paint on it, put it on the paper, and move my hand around.  There is no magic or machinery involved and it is done freehand.  Sometimes I look at a real thing or person and paint it, sometimes its a picture i took, and sometimes i just make it up.  How to tell?  If its a picture with a title like “Lisa” then probably that’s from real life, if it’s, say, a zebra-man with two samurai next to it, then that’s made up.

“What kind of paint?”  The cheapest kind they have at whatever store I am at.

So it drives me crazy when I see wannabe artists shelling out thirty bucks for tools they could make or emulate for less than a tenth of that. (If you’re serious enough to have actual fancy tools, holster the angry comments, I don’t think you’re keeping the local Hobby Lobby in business buying the faux-fancy tools.)

5 - sculpting with floss pick

Need a clay knife? Floss picks work pretty well. I used this one a LOT. Here I’m angling the articular facet for the next phalanx.

6 - blood vessel grooves

Blood vessel grooves. I think I used the blunt end of a bamboo kabob skewer to install these, with some follow-up shaping with popsicle sticks. I also straightened and shortened the claw tip a bit from the previous photo.

Funny story: a few years ago I was going through the public exhibits at a certain nameless museum and at the “touch a fossil” table an excited young docent started to explain how the “blood groove” was there to let the blood flow out of the wound so the claw wouldn’t get trapped by suction. I tried to explain that it was really there to hold the vessels that nourished the keratin sheath that covered the bony claw in life, but he was unpersuaded. I wished, for the first and only time, that I had a cast Tenontosaurus claw with me so he could explain why herbivores needed “blood grooves” on their claws, too…

7 - this is distressing

Now: detailing. I didn’t want to sculpt the claw as it was in life, I wanted a fossil claw, something that looked like it might have been left out in the rain for 145 million years. The bone I picked up on the beach, and the exposed spongiosa is just perfect for putting a realistic bone texture on stuff. The rock is a rock. I used it for nicks and gouges.

8 - all cracked up

I carve cracks with a straight pin. I carve them fairly deep, a couple of mm, so if I accidentally smudge some clay over a crack I can cut or sand it off, post-baking, and get the crack back. I don’t worry about raised edges along the edges of the cracks–these sand off in a heartbeat after baking. Just carve away.

Right after the above photo was taken, I popped the whole plate in the oven for about 45 minutes at 295 F to bake the Sculpey. There are lots of different kinds of Sculpey and other polymer clays on the market, so read the instructions on the box before you bake. Also, the baking drives off the oils that made the stuff kneadable, so save your baking for a nice day when you can have the windows open. If you’re going to bake a lot of Sculpey, you might want a separate oven for it. The vapors from the baking Sculpey do make me feel a little ill, so I get some good airflow through the house and limit my exposure. Caveat sculptor.

9 - back after baking

Here’s the claw right after baking. Some areas are smooth and shiny from being in more intimate contact with the foil. If you’re not going to sculpt the other side of something and you want a perfectly flat, smooth surface, watch out for this.

10 - droopy

The only point of this photo is to show that the baked Sculpey is not rock-hard. The tip of the claw is drooping under its own weight here. For my first, smaller claw, I carved a groove in the flat side with a Dremel and put in a section of bent hanger wire to help it maintain its shape. For this second one, I figured the other half of the claw would give it sufficient thickness to hold its shape after baking, and I was right.

11 - second side sculpt

Here’s the reverse side, sculpted using the same techniques as I used for the first side, but not baked yet. I suppose there might be some kind of Sculpey Einstein out there who can do a whole claw in one go, but I couldn’t figure out how to do both sides without leaving fingerprints everywhere, or how to support the thing while it baked, so I did the two sides sequentially. If you think of a better solution, let me know, although really this is not much extra work–about an hour, max, while I was watching Mythbusters.

12 - macrophage choking on asbestos

Now we gotta talk about asbestos for a while (this is relevant, I promise). Here’s a photomicrograph of a macrophage (a kind of white blood cell) self-impaled on some asbestos fibers, in what started out as attempted consumption of foreign material by the macrophage, and ended up closer to a crucifixion.

Here’s the deal: you have macrophages roaming around in your lungs, and when they find stuff that isn’t supposed to be there–which is pretty much everything other than your own living cells–they eat the offending material. And by “eat” I mean “engulf and try to chemically destroy”, using all kinds of profoundly noxious stuff–hydrochloric acid, hydrogen peroxide, chlorine gas. And if the offending material is extremely resistant to such treatment, as is the case with asbestos, the macrophages just keep unleashing hell. Forever. Which doesn’t dissolve the asbestos, but does eventually dissolve your lungs. Asbestos by itself doesn’t hurt you much–it’s what you do to yourself trying to get rid of it that kills you.

Why am I bringing up this depressing stuff? Partly because you are in command of a human body and you should know something about how it works. And partly because, if you have been following this little how-to, very soon you are going to be sanding your Sculpey dinosaur claw. Which is made out of plastic. Which is going to shed tiny particles of plastic into the air while you sand it. Which you are going to inhale unless you are wearing a mask. Now, I don’t know the actual resilience of baked Sculpey particles under the chemical assault your macrophages are prepared to light them up with, and I don’t recommend that you perform the experiment on yourself. I got a pack of five of these:

13 - dust mask

for two bucks at the hardware store. If you can afford ten bucks for a block of Sculpey, you can afford to spend two more to save your lungs.

This goes for sanding just about everything, by the way. It’s like germs or radiation, just because you can’t see or feel the damage doesn’t mean that it isn’t happening. Also like germs and radiation, some simple precautions are all you need to avoid the vast majority of the problems. Or you can skip them, and someday someone like me may be using your corpse to teach people about how not to care for a human body. Your pick!

14 - sanding

Sanding. I only do one pass, with 220 grit. If you start with 60 grit, you can say goodbye to all the details you put in, because they are going to be gone very quickly. Basically I’m just trying to knock off the most egregious of the rough edges. I’m not trying to get a very smooth surface–that comes next.

I didn’t take any pictures of this, but after the sandpaper I scrubbed the whole claw with 000 steel wool. I had never used this stuff before–I only learned about it from that Adam Savage TED talk–and it is pretty amazing. For one thing, it will give whatever you are sanding a shockingly smooth finish. For another, it actually goes away as you use it. You’ll start out with a full-sized bundle and after sanding for 10 minutes you’ll be down to a half-size bundle. If you’re slouching in front of the TV, it will look like a metal cat shed all over your t-shirt. The chances of actually inhaling a tiny sliver of steel and having it get all the way down into your lungs are probably pretty slim, but I masked up anyway (there are still microscopic Sculpey shards coming off at this stage). Anyway, the steel wool gives a very even appearance to the surface, so you can’t tell what areas got really hit by the sandpaper, and for me it was one of the most satisfying parts of the whole process.

15 - finished claw

And here’s the final result. On the right the tip is a little blackened from over-baking, since the right side went through the oven twice, but it’s not bad. At this point you can paint or do whatever. I haven’t experimented with painting Sculpey yet, and online sources are mixed about what works best. You don’t want to use anything thick for a primer or you’ll lose the fine details. When I do finally get around to painting, I’m going to start with flat black auto primer, just like Adam Savage used on his Maltese Falcon (which I know was resin, not Sculpey, but still), and see if that doesn’t do the trick. If you know of something better, please tell us in a comment.

Next up in this series: molding and casting.


Rexy skeleton

Earlier this spring London and I got on a building dinosaurs kick, inspired by this post at Tumblehome Learning. I used a few of these photos as filler in this post, but I haven’t talked much about what we did and what we learned.

Above is my first attempt at a wire skeleton for a papier mache dinosaur. Yes, despite being a dino-geek from the age of three on, I had never made a papier mache dinosaur before this spring. The thicker white wires are from a hanger, and the thin ones are from a reel of wire I found in the hardware section at Wal-Mart. It’s held together with masking tape, and the thick wires running down the legs of the dino are going into holes I drilled in that piece of scrap wood.

Wire jaw

Here’s part of the wireframe for my first skull. At this point I was still thinking of Alioramus. Notice the sections of drinking straw, split and popped onto the wires to bulk out the wireframe and give the papier mache more than a 2D plane to bite on.

Wire skull

Here’s that lower jaw with the rest, a skull of some kind of predatory coelurosaur. Fairly early on I abandoned the strict Alioramus plan and followed in the footsteps in Barnas Monteith at Tumblehome Learning (who posted the instructions linked above) in going for a sort of generic critter instead of any particular real-life taxon. Therefore, I was free to freewheel without having to worry too much about accuracy (Robert Frost would have said I was playing tennis with the net down). As you can see here, this is another wire job held together with duck tape, and the lower jaw already has the first layer of papier mache on.

Papier mache is pretty hard to screw up: put some water in a bowl, add flour until it gets thick, stick pieces of torn-up newspaper in the mix and put them on whatever you’re making. Anything more than that, you should learn on your own by experimentation.

Raptor skull in cardboard

Progress on “Rexy” and my skull was going too slow for London, so I knocked out a crude Velociraptor skull in cardboard for him to work on at his own pace. This became “Rapty”.

The Three Machesketeers

An early family portrait: “Rapty”, “Rexy”, and my “Uglioramus” skull. You can see the Wedel method for not messing up the dining room table: first, put down a layer of plastic trash bags taped together, then a layer of newspapers taped together. For Rexy, we put down a layer of cling wrap to keep the papier mache drips off the wood base, which was a huge win in the long run. Rapty and Ulgioramus are sitting on foil-covered pizza-baking sheets. Those turned out to be useful for…

Baking theropods

…baking skulls. Papier mache dries  s  l  o  w  l  y  in cool, wet weather. But if it will fit, you can pop your thing in the oven on low heat for 15-20 minutes and get’er done quickly. This worked for both skulls, but it worked better for Rapty. On Uglioramus, the metal expanded enough to keep poking its way out of the papier mache, so I did a lot of patching. Still probably faster than waiting for the whole thing to air-dry.

Putting in teeth

Teeth. I went a little nuts with these in terms of size (I know, those teeth won’t fit into that maxilla, but it looks rad if you switch your brain off, kind of like Jurassic Park). They’re made up of flat cardboard from a cheap box (not corrugated) layered together with wood glue to give them some thickness, and coated with more wood glue and papier mache goo to soften the contour lines.

Sealing with Titebond

Before painting I sealed the whole thing with a thin layer of Titebond wood glue. That probably wasn’t 100% necessary, given what went on next, but I knew it would get the job done and strengthen the structure.

London and Rapty

Back to “Rapty”: he got a set of teeth–one layer of thin cardboard this time–entirely speculative nasal and parietal horns courtesy of London, and a couple of coats of Kilz2 white latex primer left over from a telescope-making project. Then he was off to school for show-and-tell. Since then he’s gotten one thin coat of brown watercolor paint. Some of the holes in the skull just about closed up during papier-macheing, but since the impetus for the project was to have fun, it doesn’t trouble me.

Uglioramus in paint box

Here’s Uglioramus, also dressed in Kilz, awaiting his first coat of paint in my expensive, professional paint box. Leaving a freshly-painted object without overhead protection in this neighborhood is just asking for it to be hit by falling vegetation.

Uglioramus first coat

And here we are after the first coat. I use Krylon because it’s cheap, tough, and dries fast, but with the Kilz on I could probably use just about anything.

And that brings us up to the present. I have some ideas on how to finish Uglioramus to make it look more like a fossil skull and less like some cast-off from a flea market, but those will have to wait for another post.

The upshot of all of this is that I am not an expert on either theropod skulls or papier mache, and if a doofus like me can do this well the first time out, you can probably do as well or better yourself. And it’s cheap, messy fun. Highly recommended.

Hemisected gator

Okay, before some wag makes this point, the gator is missing a good chunk of its tail, so this is more like the left half of the anterior two-thirds of a gator. But that would make a lousy title.

We might have more to say about this in the future, but for now, I’m going to let this 1000-word-equivalent speak for itself.

Many thanks to Elizabeth Rega for the use of the gator.

Our friends Tim and Michelle Williams moved into a local house a few months ago. In the garage, they found a jam jar containing the bones of a squirrel and the remains of its rotting flesh, dated 1985: presumably a zoologist lived in that house 28 years ago, began preparing a specimen, and moved out before finishing.

Tim was inexplicably lacking in excitement over this discovery, and passed the jar to me. I cleaned the bones (holding my nose) and am now the proud owner of a plastic tub full of tiny, tiny bones. Among the most interesting are the mandibles, and here’s why. First, I’ll show you the right mandible in medial view, with its incisor sitting in its socket as it would have done in life:


The bones were clean enough that the teeth all came out of their sockets, so here is the same mandible in the same aspect to the same scale, but with the tooth removed:


I know! It’s ridiculous! You wouldn’t think it would ever fit inside the bone of the jaw! But it does — just. Here are the tooth and the jaw juxtaposed:


So there is it: the tooth literally could not be any bigger.

Rodents: they’re not quite as dull as you think.

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:

  1. You have 30 minutes total to create the cover from scratch.
  2. When the time starts, generate a batch of six random titles at the Random Book Title Generator.
  3. Choose the one you like most, and make a cover for it.
  4. Use your own name as the author.
  5. You may only use copyright-free or CC BY materials, and be prepared to demonstrate that you have done so.
  6. 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:

Year of the Beginning

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 if you don’t have an account on flickr or similar.)

Another picture from the recent ostrich dissection (click for full-size, unlabeled version). Last time we were in the middle of the neck, looking from anterior to posterior. This shot is from closer to the base of the neck, looking from posterior to anterior. A lot of the stuff is the same: the ragged cut from the saw at the meat processing plant where the ostrich was cut up; the spinal cord with the supramedullary airways above it in the neural canal; and the large interspinous ligament with diverticula on either side. We’ll have reason to refer back to some of those things in the not-too-distant future, but right now I want to draw your attention to something else: the tendons of the paired longus colli dorsalis muscles toward the top of the photo.

Here’s a modified version of Wedel and Sander (2002: fig. 2) with the course of the longus colli dorsalis highlighted in red (anterior is to the left). It is a curious aspect of bird necks that the large dorsal muscles do not insert on the neural spines but on the epipophyses (or dorsal tori or dorsal tubercles) above the postzygs. A naive approach based on beam theory would suggest that inserting on the neural spines would give those muscles more leverage, but necks are tricky and often defy such a priori predictions.

Instead of inserting on the neural spines, the longus colli dorsalis muscles originate from them, especially in the posterior part of the neck, and that’s what the photo at the top shows. From the reader’s point of view, the big interspinous ligament runs forward to attach to the posterior side of the neural spine (not visible because it’s buried in gloop, but it’s about a third of the way down from the top). The longus colli dorsalis tendons are running forward from the anterior side of the neural spine.

Fig. 20. An MRI of the mid-cervical series of an ostrich (Struthio camelus). In sagittal section, the interspinous ligaments are lighter than the surrounding muscle because of their high fat content. The neural canal is occupied by the spinal cord and supramedullary pneumatic airways. Also apparent in this image are the tendons of the longus colli dorsalis muscle originating from the neural spine. Scale bar is 4 cm.

Here’s the same thing again, also in an ostrich, but in an MRI this time (and with anterior to the right; Wedel et al. 2000: fig. 20). The dark streaks running forward from the neural spines are those longus colli dorsalis tendons. The interspinous ligament also shows up nicely as a series of white bands connecting adjacent neural spines.


Those ostrich necks I went to Oro Grande to get last Thursday? Vanessa and I started dissecting them last Friday. The necks came to us pre-cut into segments with two to three vertebrae per segment. The transverse cuts were made without regard for joints so we got a bunch of cross sections at varying points through the vertebrae. This was fortuitous; we got to see a bunch of cool stuff at the cut faces, and those cut faces gave us convenient avenues for picking up structures and dissecting them out further.

In particular, the pneumatic diverticula in the neck of this ostrich were really prominent and not hard at all to see and to follow. The photo above shows most of the external diverticula; click through for the full-resolution, unlabeled version. The only ones that aren’t shown or labeled are the diverticula around the esophagus and trachea (which had already been stripped off the neck segments, so those diverticula were simply gone), those around carotid arteries, which are probably buried in the gloop toward the bottom of the photo, and the intermuscular diverticula, of which we found a few in parting out the dorsal and lateral neck muscles.

There is one final group of diverticula that are shown in the photo but not labeled: the interosseous diverticula that fill the air spaces inside the bone.

We have tons of cool photos from this dissection, so expect more posts on this stuff in the future.

For previous posts showing diverticula in bird neck dissections, see:

Things to Make and Do, part 7: fun with rhea necks

Things to Make and Do, part 7b: more fun with rhea necks (admittedly, not the most creative title ever)