February 11, 2014
Somewhat lamely, this is the only slide I had in about lighting. I left it up while I talked about the most important points, which are:
- Don’t use a flash unless you absolutely have to.
- If you can swing it, the common convention is to have specimens illuminated from the upper left.*
- If you have the time, it’s not a bad idea to bracket your Goldilocks shot with brighter and darker photos, by fiddling with your camera settings.
* I happily violate this convetion if illumination from another angle shows the specimen to better advantage–and if I have any control over illumination. Working with big bones in some collections, you basically have overhead florescent lights and that’s it. The NHM shot above may look not-so-hot, but there we at least had a desk lamp we could move around. In a lot of places I’ve worked, I didn’t have even that.
The other posts in this series are here.
February 10, 2014
Let it never be said that we don’t take good care of our commenters. Heck, we’ll even degrade ourselves by blogging about theropods, if that’s what it takes to keep you all happy.
Today’s post is a response to this comment by Dean, asking for lateral view photos of the skull of Giraffatitan. Mike and I did get to spend some quality time with the T1 skull (a.k.a. “Old Toilet-Face”) when we were in Berlin in 2008.
Unfortunately, most of our photos turned out not-so-hot. The room around the skull was not large, so we couldn’t get back very far from it. Hence our photos are plagued by perspective distortions.
Also, we didn’t have a tripod along and the light level was fairly low, and the combination of handheld shots and long exposure times meant that most of the shots are at least a little blurry.
BUT. It was still a thrill to see that skull up close.
The crazy thing about Giraffatitan is that the skull looks like it’s going to be pretty sweet when you see it from the side. Because you’re thinking it’s going to be kinda narrow, like a giraffe’s head. Then you get even a partial front view and suddenly the animal’s whole skull looks like a partially-deflated whoopie cushion (whereas in life it looked like a mostly-inflated whoopie cushion). And then you have to live with the knowledge that one of the most majestic animals that ever lived on Earth was afflicted with derpty-face. I’ll bet they went extinct from shame.
Still, there is some cool anatomy to see here, especially the snout-troughs leading down from the external nares, and the neurovascular foramina on the maxillae.
And, crucially, brachiosaurs had the good taste to hide their freakish countenances 45 feet up, where they could be safely ignored by everyone other than pterosaurs and birds. This has not escaped the notice of exhibit designers:
Go here for the unmarked original.
January 31, 2014
Back in the early aughts Cal Acad did a huge exhibit simply titled, “Skulls”. It was extremely rad, and I could have been running a separate blog this whole time with nothing but photos from that exhibit. (Update: the website for the exhibit is still going. Check it out.) I was just sorting through some old folders and found some favorites. The photo above is the wall of California sea lion skulls, 900-odd in all, arranged from the biggest, gnarliest males on one end to the most gracile females on the other end.
They also had quite a few pathological sea lion skulls. Here are two that haunted me–they got tangled up in fishing lines that slowly sawed through their skulls and into their brains, killing them.
This elk had a pretty funky growth on its right dentary.
But easily the most “Naw!”-inducing pathology in the whole exhibit was this poor deer, which has a pathological growth the size and shape of a big pastry where its right eye used to be. I don’t know if it’s just a coincidence that its antlers are all wonky, too–maybe Darren will show up and enlighten us.
So if you’re feeling down, you can at least console yourself that you don’t have a flyblown, pus-leaking cinnamon roll of pathological bone growing on your face. Have a nice day!
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.
December 17, 2013
Yes, it’s bear skulls on the brain lately. I have nothing scientific to say here, I was just going through old files and found myself struck by the beautiful form and texture of the bones. The photos are all close-ups of this skull of an American black bear, Ursus americanus.
Part of the forehead, where the nasal bones (bottom center) and maxillae (either side) meet the frontals (top).
The left temporal bone in posterodorsal view; anterior is to the left. The open web of bone in the middle of the photo is one of the pneumatic sinuses inside the temporal bone. The round hole just above the web enclosed a blood vessel in life. The half-tube on the right is the bottom half of external auditory meatus, or bony ear-hole (where you stick the Q-tip when you clean your ears, if you’re a reckless, safety-warning-diregarding outlaw). All of this got exposed when a bullet or shotgun slug took the back quarter of this bear’s head off, as described here.
Personally I’d be happier if the skull was still in the bear and the bear was still doing its bearish business, but as long as it’s dead anyway, we might as well learn what we can from the remains (my universal policy on dead animals). And also just stop now and then to appreciate their natural intricacy and beauty.
December 10, 2013
Many thanks to everyone who played pin-the-skull-on-the-carnivore. The answers are down at the bottom of this post, so if you’ve just arrived here and want to take the challenge, go here before you scroll down.
To fill up some space, let me point out how crazy variable the skulls of black bears, Ursus americanus, are.
Here’s the one I helped dig up, missing the occipital region. Note the double inflection in the dorsal outline that separates the forehead from both the snout and top of the head, and the way the nasal bones stick out at a very different angle from the maxilla.
Here’s the skull of a black bear from the La Brea tar pits, in the Page Museum in L.A. I don’t know if this one was female or juvenile or what, but the dorsal margin of the skull is one mostly-smooth curve from occiput almost to incisors, with the nasals scarcely deviating at all. Lest you think these differences were caused by evolutionary change rather than intraspecific variation, similar “roundhead” bear skulls from modern times are here and here and near the bottom of this page.
It’s this variability that first got me thinking about doing the Carnivore Skull Challenge. I saw a couple of photos of skulls of wolverines, and except for having carnassial cheek teeth instead of flatter premolars and molars, the wolverine skulls look like they could fit right into the span of black bear skull variability (in shape; obviously they’re not nearly as big). Then I saw a hyena skull and thought that it wasn’t that far off from a wolverine either. A little more searching for plausible distractors and I was all set.
Here are the answers, by the way:
It’s kind of ironic, then, that the first two people to venture identifications picked out the black bear right away. In the very first comment, Dean got it almost all right except for swapping the seal and the fossa. Dean was also the first to get all of the skulls correctly identified, albeit on his second pass. Markus Bühler (of Cthulhu-sculpting fame) was the first to get them all the first time. Tom Nutter, our own Darren Naish, and microecos Neil also aced the test, although in light of the Page Museum bear skull shown above, I was amused to see Darren’s “D: Bear. Because forehead.” I guess it’s one of those presence-of-forehead-means-bear, absence-of-forehead-does-not-rule-out-bear things that logicians are always going on about.
I was really happy to see people getting the wolverine and hyena mixed up, because they really do look strikingly similar to me. It’s almost like hyena + bear = wolverine.
Brian Engh asked on Facebook when I was going to do one for sauropods. Patience, good sir! It’s on my to-do list.
Something very different, and very unexpected, tomorrow.
December 9, 2013
In this image I have assembled photos of skulls (or casts of skulls) of six extant carnivores. I exclusively used photos from the Skulls Unlimited website because they had all the taxa I wanted, lit about the same and photographed from similar angles. The omission of scale indicators is deliberate.
Your mission, should you choose to accept it, is to match these skulls with the animals they came from. Here are their currently-understood hierarchical relationships, scientific names, and common names (aside: I know this is ugly, is there a way to make nested tables in WordPress?).
- – Herpestoidea
- – – – Eupleridae
- – – – – – Fossa, Cryptoprocta ferox
- – – – Hyaenidae
- – – – – – Brown hyena, Hyaena brunnea
- – Arctoidea
- – – – Ursoidea
- – – – – – American black bear, Ursus americanus
- – – – Musteloidea
- – – – – – European badger, Meles meles
- – – – – – Wolverine, Gulo gulo
- – – – Pinnipedia
- – – – – – Mediterranean monk seal, Monachus monachus
If you accept the challenge, leave your guesses as comments below, but only if you’ve played fair–no checking websites, references, or your own skull collection! Don’t worry about being wrong, I freely admit that I would have flunked this bigtime if anyone else had inflicted it on me. I decided to set up this challenge after I noticed the striking similarity between two of these critters in particular; I’ll tell you which two when I post the reveal in a day or two.