I think it’s fair to say that this “bifurcation heat-map”, from Wedel and Taylor (2013a: figure 9), has been one of the best-received illustrations that we’ve prepared:
Back when the paper came out, Matt rashly said “Stand by for a post by Mike explaining how it came it be” — a post which has not materialised. Until now!
This illustration was (apart from some minor tweaking) produced by a program that I wrote for that purpose, snappily named “vcd2svg“. That name is because it converts a vertebral column description (VCD) into a scalable vector graphics (SVG) file, which you can look at with a web-browser or load into an image editor for further processing.
The vertebral column description is in a format designed for this purpose, and I think it’s fairly intuitive. Here, for example, is the fragment describing the first three lines of the figure above:
Taxon: Apatosaurus louisae
Specimen: CM 3018
Taxon: Apatosaurus parvus
Specimen: UWGM 155556/CM 563
Taxon: Apatosaurus ajax
Specimen: NMST-PV 20375
Basically, you draw little ASCII pictures of the vertebral column. Other directives in the file explain how to draw the various glyphs represented by (in this case) “Y”, “V”, “u”, and “n”.
It’s pretty flexible. We used the same program to generate the right-hand side (though not the phylogenetic tree) of Wedel and Taylor (2013b: figure 2):
The reason I mention this is because I released the software today under the GNU General Public Licence v3.0, which is kind of like CC By-SA. It’s free for anyone to download, use, modify and redistribute either verbatim or in modified form, subject only to attribution and the requirement that the same licence be used for modified versions.
vcd2svg is written in Perl, and implemented in part by the SVG::VCD module, which is included in the package. It’s available as a CPAN module and on GitHub. There’s documentation of the command-line vcd2svg program, and of the VCD file format. Also included in the distribution are two documented examples: the bifurcation heat-map and the caudal pneumaticity diagram.
Folks, please use it! And feel free to contribute, too: as the change-log notes, there’s work still to be done, and I’ll be happy to take pull requests from those of you who are programmers. And whether you’re a programmer or not, if you find a bug, or want a new feature, feel free to file an issue.
A final thought: in academia, you don’t really get credit for writing software. So to convert the work that went into this release into some kind of coin, I’ll probably have to write a short paper describing it, and let that stand as a proxy for the actual program. Hopefully people will cite that paper when they generate a figure using the software, the way we all reflexively cite Swofford every time we use PAUP*.
Update (12 April 2014)
- Swofford, D. L. 2002. PAUP*: phylogenetic analysis using parsimony (* and other methods). Sinauer Associates, Sunderland, MA.
- Wedel, M.J., and Taylor, M.P. 2013. Neural spine bifurcation in sauropod dinosaurs of the Morrison Formation: ontogenetic and phylogenetic implications. Palarch’s Journal of Vertebrate Palaeontology 10(1): 1-34. ISSN 1567-2158.
- Wedel, Mathew J., and Michael P. Taylor. 2013. Caudal pneumaticity and pneumatic hiatuses in the sauropod dinosaurs Giraffatitan and Apatosaurus.PLOS ONE 8(10):e78213. 14 pages. doi:10.1371/journal.pone.0078213 [PDF]
January 24, 2014
Here’s a nice thing: friends and relatives just assume (correctly) that I will want whatever dead animals they find. So I was not completely surprised when I got a call from my brother Ryan (pillager of the Earth) asking if I wanted a dead mouse he’d found mummified at the back of an unused cupboard. Happily this was over the holidays so I could get the specimen in person and not have to deal with mailing it.
This was not destined to be my mummified mouse, however. My son, London, has started a collection of his own. One of the first real skulls in his collection was that of a rat that we found dead in our front yard last year. I cut off its head and we boiled and cleaned the skull together (I still need to post about that). Then we mounted it in a clear plastic bottle that had previously contained toothpicks, so he could take it for show-and-tell. Last fall a second rat turned up dead in the yard; that one is still in the freezer, awaiting complete skeletonization. The mystery of the plague of dead rats was solved when we got home one evening and found our cat, Moe, in the front yard with only the hind leg of a third rat hanging out of his mouth. If I could just train him to kill them and not eat them, we could make a rat army…
Funny side-note: we keep Skulls Unlimited catalogs around for leisure reading. London was looking through one not long after we prepped his rat skull and he saw that you could get a fully-prepared natural bone skull for about twenty bucks. That price seems about right to me, given the amount of work and care that has to go into cleaning, but London was outraged: “Why would people pay TWENTY DOLLARS for a rat skull when they could just clean their own!?”
That’s my boy! I didn’t have the heart to tell him that some people don’t have a ready supply of rats lying around. He’s not old enough to understand that level of deprivation.
So, obviously the mummified mouse was going to show-and-tell. But I didn’t want it to get destroyed. My cheap and low-tech solution was to get a rigid plastic display box from the local hobby store ($5.99 for a two-pack) and stuff it with cotton balls. We cleared some of the cotton around the skull first so it would be more visible. Knowing how third-graders can be when exciting things get passed around, I also glued the lid on. The mouse and the cotton balls are completely immobile even when violently shaken, and hopefully they’ll stay that way indefinitely. I forgot to include a scale bar in either of these photos or to measure my damned murine, but the box lid is 5 inches on side. HeroClix Knifehead showed up because kaiju are notorious attention hogs.
Now, to see if Mousenkhamun can survive the rigors of third grade. I’ll keep you posted.
December 18, 2013
When we last left my better half, Dr. Vicki Wedel, she was helping to identify a Jane Doe who had been dead for 37 years by counting growth rings in the woman’s teeth. That case nicely illustrated Vicki’s overriding interest: to advance forensic anthropology by developing new methods and refining existing ones. To that end, for the past few years she has been working with her PhD advisor, Dr. Alison Galloway at UC Santa Cruz, to revise and update Alison’s 1999 book, Broken Bones: Anthropological Analysis of Blunt Force Trauma. The revised and much expanded (504 pages vs 371) second edition, co-edited by Vicki and Alison, came out Monday (Amazon, Amazon.co.uk).
You can read the whole table of contents on Amazon (click to look INSIDE!), but the short short version is that the book has three major sections. The first covers the science and practice of trauma analysis (pp. 5-130), and the second classifies hundreds of common fractures throughout the skeleton, with illustrations (pp. 133-313). The chapters in these sections were all written by Vicki, Alison, and another of Alison’s former students, Dr. Lauren Zephro, solo and in varying combinations. Lauren, whom I always think of as “the Amazon cop”, is a 6-foot blackbelt forensic anthropologist for the Santa Cruz County Sheriff’s Office. If push came to shove I have no doubt that she could beat me to death with her bare hands and then produce a technical analysis of my corpse.
The final section (pp. 314-410) consists of nine case studies contributed by forensic anthropologists, pathologists, medical examiners, forensic and medical artists, and a DoD casualty analyst, based across the Anglophone world from Hawaii to Scotland. There’s some grim stuff in there: trauma to the homeless and elderly, from intimate partner violence, and from child abuse. It’s gut-churningly awful that the defenseless suffer from bone-breaking violence; it’s always been amazing to me that people like Vicki, Alison, Lauren, and the other contributors have both the courage to face these horrors and the technical chops to make the unspeakable solvable.
Beyond that unavoidable darkness, if you’re interested in the many, varied, and often just plain weird ways in which people die, the book is a treasure trove. There’s an elderly woman lying on her deathbed for six years, slowly turning into a natural mummy… (wait for it) …while her daughter went on living in the same house. There’s a classification of plane crashes with a description of what human remains will be found and over what area. There are people hit by trains; the funniest line in this very serious book is the deadpan and unsurprising, “The typical pedestrian hit by a train is male and often highly intoxicated.”
That’s from the top of page 122. At the bottom of the same page is my one contribution to the book, which also appears as the cover art (yeah, nepotism, whatcha gonna do). There’s a story behind this. This guy–yes, male, dunno if he was intoxicated–was hit by a train and his head was sheared in half, with the somewhat fractured but mostly intact facial skeleton separated by a lot of missing bone from the occipital region. With no way to obtain the deceased guy’s permission to use his mortal remains in the book, Alison and Vicki didn’t feel comfortable including their photos, so I spent a weekend bashing out a technical drawing for them to use instead. That reawakened my interest in pen-and-ink work and led to the dödö pöst.
I should say two things right here: first, that yes, I am hijacking the rest of the post to talk about myself. (Is anyone really surprised? I thought not.) Second, that I have had no training and possibly my stippling violates Art Rules or best practice guidelines of which I am ignorant. But I hope it also illustrates what can be achieved in a couple of days, with about $15 worth of supplies, by a guy whose only rule is “möre döts”.
So anyway, if you’re curious, here’s the method I use for my pen-and-ink illustrations:
- Get a decent-sized photo of the object to be drawn. I usually roll with $2 8x10s from MalWart, in this case one for each half of the skull.
- Tape the photo down to your work surface. I have a large, incredibly hard, perfectly smooth cutting board that I use for this, but in a pinch you could use just about anything, including just a larger piece of paper. Cardboard off the backs of desk calendars is nice.
- Over the photo, tape down a piece of tracing paper.
- Lightly trace the outline of the photo and all the major details in pencil.
- Once you’ve gone as far as you can with that, peel up one side of the tracing paper, unstick the photo from the work surface, and remove it. Stick the tracing paper back down the work surface.
- Using the uncovered photo as a reference, pencil in any other salient details by eye. Also contour lines for shadows. All of the pencil lines are going to be erased later, so don’t be shy.
- Whenever you decide you’re done with the pencil, get a good pen and start tracing, directly over the pencil lines. I tend not to be too persnicketty about my tools but decent pens are a real help here. For these recent works, I picked up a three-pack of beige-tubed Micron pens for $7 (this set).
- In all of the following pen-related steps, be careful to keep your big stupid hand and arm off the wet ink you just laid down–one careless smear can ruin a few hours’ work. Having a work surface that you can rotate is nice, so your pen hand can approach the drawing from any angle. Anytime I have to lay my hand on the drawing, I put down a piece of clean scrap paper first. Even if the underlying ink is dry, it just feels like a smart precaution.
- Once the lines are on, add döts to taste. With a little experimentation, you can get patterns of dots to not only indicate light and dark but also suggest textures. Different pen tips and amounts of pressure will yield dots of different sizes, which can also be useful. Dense, overlapping dots can produce an effect similar to scratchboard. BTW, sometimes I do “gear down” and place each dot with thought and care, but in the dense sections I just rat-a-tat-tat like a Lilliputian jackhammer. Try different speeds and see what you can tolerate.
- When you’re done dötting, at least to a first approximation, and you’re dead certain the ink is all dry, get a decent eraser and erase all of the pencil lines. I used one of those clicky mechanical erasers because it was cheap and soft enough to not tear up the paper.
- Re-ink any lines lightened by the erasing. I find that the döts are usually unaffected, but lines are often knocked down a bit by the eraser work. I suppose it would be cleaner to just draw natively in pen, with no prior pencilling and therefore no erasing, but the few times I’ve tried it, it hasn’t gone well. YMMV. If you’re drawing a 3D solid, this is a good time to employ an old illustrator’s trick, which is to make the bottom outline heavier and darker than the rest, to subtly convey a sense of weight.
- Scan, touch up as needed in GIMP, post to blog, bask in self-admiration.
In this case I had a few more steps, which consisted of making variants of the drawing and test-driving them by Vicki and Alison so they could pick their favorites.
This is just embarrassing: after scanning the two drawings and doing a little touch-up, I just scooted them together until they looked like a skull. The problem is that the occiput is nowhere near anatomical position. See that flange of bone above the ear-hole, pointed down and right at a 45-degree angle? That’s the back end of the zygomatic arch, and it should be aimed at the forward stump of the arch, which is just down and back from the eye socket.
Here’s the B version, where I was working entirely off of the zygomatic arch ends, and trying to get the skull into anatomical position. Scientifically this is probably the best variant I produced (I’m not claiming it’s the best possible), but aesthetically it’s a little crowded.
I’ll spare you versions C-E, all of which just scooted the back end of the skull around in an attempt to find a balance between scientific and aesthetic concerns. Here’s the winning F version, which got used for the figure, and became the seed variant for the cover.
For the cover, we tried a lot of things, including the white skull on a black background, and one that was simply inverted from the figure. By this point the publisher had sent Vicki some test versions of the cover, and I thought it would be cool if the drawing was in the same color as the cover text, so I sampled that color from the publisher’s sample cover image and applied it to all of the drawn bits. They knocked it down a few tones for the printed version, so happily it’s not this garish.
Incidentally, I had never tried to replace a bunch of discontinuous areas of the same color with another color in GIMP, so I had to look it up. The two key steps are Select > By color, with the threshold set to zero (or not, if you want to grab a bunch of related colors at once), and “Fill whole selection” in the Bucket tool. Hat tip to this dude and his commenters.
One last step: I thought the bare, unfilled yellow version looked too flat, so I tried different levels of fill to make the skull pop out from the background. I didn’t use bucket fill here–too fiddly with so many dots and edges. Instead I created a new layer of solid yellow and dropped the opacity to 17%. Then went to the drawing layer and used the magic wand tool to select the whole non-skull background. Then popped back to the yellow layer and cleared that selection, leaving yellow fill only in the boundaries of the skull outline. I also tried 10% and 25% opacity for the fill layer, but 10% was too subtle and 25% was starting to swamp some of the detail in the drawing. Between goofing around with colors and opacity levels we went through 10 versions at this stage, of which the one above is the ultimate champion.
So, that’s how the cover art came to be. Back to the book. There’s a bibliography with 1237 references (Vicki knows), and an index. The book is hardbound, with a printed cover and no dustjacket, and IMHO reasonably priced at $65, currently a few bucks less on Amazon. You probably already know whether you want a copy. If so, do the right thing–it’s not too late to get it by Christmas.
October 22, 2013
It shouldn’t come as a huge surprise to regular readers that PeerJ is Matt’s and my favourite journal. Reasons include its super-fast turnaround, beautiful formatting that doesn’t look like a facsimile of 1980s printed journals, and its responsiveness to authors and readers. But the top reason is undoubtedly its openness: not only are the article open access, but the peer-review process is also (optionally) open, and of course PeerJ preprints are inherently open science.
It’s a baby Parasaurolophus, but despite being a stinkin’ ornithopod it’s a fascinating specimen for a lot of reasons. For one thing, it’s the most complete known Parasaurolophus. For another, its young age enables new insights into hadrosaur ontogeny. It’s really nicely preserved, with soft-tissue preservation of both the skin and the beak. The most important aspect of the preservation may be that C-scanning shows the cranial airways clearly:
This makes it possible for the new specimen to show us the ontogenetic trajectory of Parasaurolophus – specifically to see how its distinctive tubular crest grew.
But none of this goodness is the reason that we at SV-POW! Towers are excited about this paper. The special sauce is the ground-breaking degree of openness in how the specimen is presented. Not only is the paper itself open access (and the 28 beautiful illustrations correspondingly open, and available in high-resolution versions). But best of all, CT scan data, surface models and segmentation data are freely available on FigShare. That’s all the 3d data that the team produced: everything they used in writing the paper is free for us all. We can use it to verify or falsify their conclusions; we can use it to make new mechanical models; we can use it to make replicas of the bones on 3d printers. In short: we can do science on this specimen, to a degree that’s never been possible with any previously published dinosaur.
This is great, and it shows a generosity of spirit from Andy Farke and his co-authors.
But more than that: I think it’s a great career move. Not so long ago, I might have answered the question “should we release our data?” with a snarky answer: “it depends on why you have a science career: to advance science, or to advance your career”. I don’t see it that way any more. By giving away their data, Farke’s team are certainly not precluding using it themselves as the basis for more papers — and if others use it in their work, then Farke et al. will get cited more. Everyone wins.
Open it up, folks. Do work worthy of giants, and then let others stand freely on your shoulders. They won’t weigh you down; if anything, they’ll lift you up.
Farke, Andrew A., Derek J. Chok, Annisa Herrero, Brandon Scolieri, and Sarah Werning. 2013. Ontogeny in the tube-crested dinosaur Parasaurolophus (Hadrosauridae) and heterochrony in hadrosaurids. PeerJ 1:e182. http://dx.doi.org/10.7717/peerj.182
The LSE Impact blog has a new post, Berlin 11 satellite conference encourages students and early stage researchers to influence shift towards Open Access. Thinking about this, Jon Tennant (@Protohedgehog) just tweeted this important idea:
Would be nice to see a breakdown of OA vs non-OA publications based on career-stage of first author. Might be a wake-up call.
It would be very useful. It makes me think of Zen Faulkes’s important 2011 blog-post, What have you done lately that needed tenure?. We should be seeing the big push towards open access coming from senior academics who are established in their roles don’t need to scrabble around for jobs like early-career researchers. Yet my impression is that in fact early-career researchers are doing a lot of the pro-open heavy lifting.
Is that impression true?
We should find out.
Here’s one possible experimental design: take a random sample of 100 Ph.D students, 100 post-docs, 100 early-career researchers in tenure-track jobs and 100 tenured researchers. For each of them, analyse their last ten years of publications and determine what proportion are paywalled, what proportion are free to read (e,g, on arXiv or in an all-rights-reserved IR), and what proportion are true (BOAI-compliant) open access.
An alternative approach would be to randomly sample 1000 open-access papers (from PLOS and BMC journals, for example), and 1000 paywalled papers (from Elsevier and Springer, say) and find the career-stage of their authors. I’m not sure which approach would be better?
Who is going to do this?
I think it would be a nice, tractable first project for someone who wants to get into academic research but hasn’t previously published. It would be hugely useful, and I’m guessing widely cited. Does anyone fancy it?
September 9, 2013
I was at the Oklahoma Museum of Natural History in March to look at their Apatosaurus material, so I got to see the newly-mounted baby apatosaur in the “Clash of the Titans” exhibit (more photos of that exhibit in this post). How much of this is real (i.e., cast from real bones, rather than sculpted)? Most of the vertebral centra, a few of the neural arches, some of the limb girdle bones, and most of the long bones of the limbs. All of the missing elements–skull, neural arches, ribs, appendicular bits–were sculpted by the OMNH head preparator, Kyle Davies. Kyle is one of those frighteningly talented people who, if they don’t have what they need, will just freaking build it from scratch. Over the years he has helped me out a LOT with the OMNH sauropod material–including building a clamshell storage jacket for the referred scapula of Brontomerus so we could photograph it from the lateral side–so it’s about time I gave him some props.
Case in point: this sweet atlas-axis complex that Kyle sculpted for the juvenile Apatosaurus mount.
Most fish, amphibians, and other non-amniote tetrapods only have a single specialized vertebra for attaching to the skull. But amniotes have two: a ring- or doughnut-shaped first cervical vertebra (the atlas) that articulates with the occipital condyle(s) of the skull, and a second cervical vertebra (the axis) that articulates with the atlas and sometimes with the skull as well. Mammals have paired occipital condyles on the backs or bottoms of our skulls, so our skulls rock up and down on the atlas (nodding “yes” motion), and our skull+atlas rotates around a peg of bone on the axis called the odontoid process or dens epistrophei (shaking head “no” motion). As shown in the photos and diagrams below, the dens of the axis is actually part of the atlas that fuses to the second vertebra instead of the first. Also, reptiles, including dinosaurs and birds, tend to have a single ball-shaped occipital condyle that fits into the round socket formed by the atlas, so their “yes” and “no” motions are less segregated by location.
Anyway, the whole shebang is often referred to as the atlas-axis complex, and that’s the reconstructed setup for a baby Apatosaurus in the photo above. In addition to making a dull-colored one for the mount, Kyle made this festive version for the vert paleo teaching collection. Why so polychromatic?
Because in fact he built two: the fully assembled one two photos above, and a completely disassembled one, some of which is shown in this photo (I had to move the bigger bits out of the tray so they wouldn’t block the key card at the back). I originally composed this post as a tutorial. But frankly, since Kyle did all of the heavy lifting of (a) making the thing in the first place, (2) making a color-coded key to it, and (d) giving me permission to post these photos, it would be redundant to walk through every element. So think of this as a self-study rather than a tutorial.
Oh, all right, here’s a labeled version. Note that normally in an adult animal the single piece of bone called the atlas would consist of the paired atlas neural arches (na1) and single atlas intercentrum (ic1), and would probably have a pair of fused cervical ribs (r1). Everything else would be fused together to form the axis, including the atlas pleurocentrum (c1), which forms the odontoid process or dens epistrophei (etymologically the “tooth” of the axis).
Here’s the complete Romer (1956) figure from the key card, with a mammalian atlas-axis complex for comparison. Incidentally, the entire book this is drawn from, Osteology of the Reptiles, is freely available online.
And here’s the complete Gilmore (1936) figure. Sorry for the craptastic scan–amazingly, this one is NOT freely available online as far as I can tell, and Mike and I have been trying to get good scans of the plates for years. Getting back on topic, single-headed atlantal cervical ribs have been found in several sauropods, especially Camarasaurus where several examples are known, so they were probably a regular feature, even though they aren’t always preserved.
Also, as noted in this post, it is odd that in this specimen of Apatosaurus the cervical ribs had not fused to the first two vertebrae, even though they normally do, and despite the fact that the vertebrae had fused to each other, even though they normally don’t. Further demonstration, if any were needed, that sauropod skeletal fusions were wacky.
For comparison to the above images, here is the atlas-axis complex in the synapsid Varanops, from Campione and Reisz (2011: fig. 2C).
Those proatlas thingies are present in some sauropods, but that’s about all I know about them, so I’ll say no more for now.
There is a good overview of the atlas-axis complex with lots of photos of vertebrae of extant animals on this page.
Previous SV-POW! posts dealing with atlantes and axes (that’s right) include:
- A fused atlas and axis in Apatosaurus
- Yet more uninformed noodling on the future of scientific publishing and that kind of thing
- Another mystery: embossed laminae and “unfossae”
- Tutorial 15: the bones of the sauropod skeleton
- Campione, N.E. and Reisz, R.R. 2011. Morphology and evolutionary significance of the atlas−axis complex in varanopid synapsids. Acta Palaeontologica Polonica 56 (4): 739–748.
- Gilmore, C.W. 1936. Osteology of Apatosaurus with special reference to specimens in the Carnegie Museum. Memoirs of the Carnegie Museum 11: 175-300.
- Romer, A.S. 1956. Osteology of the Reptiles. University of Chicago Press, Chicago. 772 pp.
April 27, 2013
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.
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.
Here’s a lump after some kneading. My work surface here is a dinner plate covered with aluminum foil.
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.
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.)
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.
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…
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.
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.
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.
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.
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.
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:
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!
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.
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.
April 26, 2013
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.
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.
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.
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”.
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 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.
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.
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.
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.
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.
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.
January 24, 2013
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.
January 22, 2013
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.