Raptorex flesh head with feather detail. Photo © Erin Fitzgerald and Tyler Keillor, courtesy Project Exploration.

by Danica Tiu

With us today are Erin Fitzgerald and Tyler Keillor, the creative masterminds behind bringing Raptorex to life. Readers of Project Exploration blog might not be familiar with the name Erin Fitzgerald, perhaps because she is one of the lab’s newer employees. Although Erin has actually been working at the lab for a few years now, Raptorex is her first flesh model reconstruction.

Q: Erin, could you tell us about yourself, your background, and how you became involved in reconstructing Raptorex?

University of Chicago Fossil Lab staff member Erin Fitzgerald with Raptorex flesh head. Photo © Bob Masek, courtesy Project Exploration

Erin: I have an art background and came in with a lot of art knowledge; my goal was to do something artistic along with science, though bridging the gap and applying science to art wasn’t something I had experience with. What I originally wanted to explore was more 2D painting, but I eventually became interested in 3D models. I asked Paul to see if I could be Tyler’s apprentice because it was important to me to speak to and learn from somebody who knew how to bridge the science and art gap. By working with Tyler, I was able to observe his methods and learn about the type of information he looks for to understand, scientifically, what something would look like and how to apply that information to art. After working with Tyler for a while, Paul mentioned, that there was a new flesh model—Raptorex—in the works, and that maybe I’d like to apply all that I learned from Tyler to this new dinosaur. About six months later, I started to work on Raptorex with a little bit of Tyler’s guidance .

Q: So how did you merge scientific fact and art to create Raptorex?

University of Chicago Fossil Lab staff member Tyler Keillor with Herrerasaurus flesh head. Photo © Kari Keillor, courtesy Project Exploration

Tyler: It’s interestingwe had this really nice model of the skull as a starting point. If you look at the time-lapse for this flesh model, you can see that Erin started with skull and started sculpting on top of that. Artistically, you still have a lot of choices you have to make about what the details, the flesh, will look like. I know Erin spent some time looking at some animals that are alive today; for example, [she looked at] the digimorph website, where you can pull up cross-sectional CT scans of lizards and birds and other animals that are alive today. Using this website, you can figure out anatomical things, such as where the throat, the esophagus, and trachea fall in the neck of a bird or a big lizard. That was helpful in determining what flesh and soft tissue this Raptorex should have on its neck and on its throat.

Erin: After we figured out the soft tissue and internal parts placement, we needed to figure out the width of the throat and the girth of the neck by looking at the cervical ribs. To do so, I first needed to decide how I wanted the model to look so that we could determine the vertebrae placement— – did I want Raptorex looking up, looking down, or posed? The position I chose used Raptorex’s first nine vertebrae, which is all of the cervical vertebrae. Then, I laid out the vertebrae in life-position to see how far apart each vertebrae was, as well as how far the head was from the first vertebrae, so that I could see how much soft tissue lay between all of these bones. Next, I pulled out the 9 nine cervical ribs and figured out how they attached to the verts— – the rib placement clued us into neck diameter. With the verts and ribs as a guide, we then applied our knowledge of soft tissue to created a fleshed-out neck.

Q: While you had skeletal evidence for reconstructing Raptorex’s body, how did you decide on skin color, feathers, and other features that were not preserved?

Tyler: There are choices that every artist can make that are different about what this thing would look like in the flesh. Things that are speculative, but very probable, are a kind of pouch under the throat of the animal that looks like it is really wrinkly and folded up. You can imagine that the dinosaur could have used it to display—it could have inflated it or, possibly, it would have been colorful. That type of soft tissue we have no direct record of, so our guess is derived from looking at living animals, like iguanas or lizards or birds even that have big throat pouches to make a visual display of some kind.

Q: what about the decision to put proto-feathers on this thing?

Erin: We decided to put proto-feathers on Raptorex because there is speculation that these primitive therapods evolved into birds; they show a number of bird traits. We also referenced a dinosaur called dilong, which had an outline of feathers. Since dilong bore a strong resemblance to this animal, it seemed possible that Raptorex had feathers. As for what the feathers actually looked like, we thought that Raptorex’s proto-feathers would look more like chicken down—an intermediary before turning into feathers. However, finding the perfect proto-feather material was a little difficult. In our minds, a proto-feather would look more like a barb—a single strand of feather—rather than a flight feather —a feather with one barb with a number of barbs off of that. Ultimately, we ended up creating proto-feathers out of ostrich feathers.

Tyler: But these aren’t ostrich feathers as is; the feathers on this model were made by taking an ostrich feather and snipping off, from the central vein, the small barbs of the ostrich feather. Then, each one of those small pieces was possible cut in half or into thirds. Afterwards, those tiny pieces were glued on to make the Raptorex feathers. They ended up giving us something very simple, a very simple structure, just a central shaft with a bit of fuzziness to it, but nothing that looks like a flight feather, like Erin said. Essentially, we were trying to create proto-feathers without anyone really having seen what one looks like short of a smashed, fossilized impression of these feathers. This is a suggestion of what they could have looked like.

Q: If Raptorex was a potential bird predecessor, why is it only partially covered in feathers?

Erin: We decided not to completely cover the animal in feathers primarily because, like many birds nowadays, the entire body is not covered in feathers— – they are either very spaced out and overlap each other, and if you pull the feathers back, there are a lot of parts that are pretty bare. Also, since this is the beginning stage of an evolving animal-bird, it wasn’t completely necessary to have feathers.

Tyler: Not to say that Raptorex turned into a bird, but to say that it’s in the same family of all these strange experiments, all these little predatory dinosaurs that seem to have interesting bird-like characteristics. Following up what Erin said, if the body isn’t fully feathered as an adult, it’s possibly that as a chick, a hatchling, it may have had feathers all over its body the way very small chicks do. And as it grew into adult size, it just kept some feathery regions and display areas, which is why the feathers along the midline and the top of the neck have a pattern to them, a bit of a stripe. So there are remnants of feathers on other parts of the body, like along the side of the neck where it would meet the underside of the body. This just follows the idea that that’s one of the regions that would be feathered, while the neck would be one of those naked areas.

Raptorex flesh head during construction. Photo © Erin Fitzgerald and Tyler Keillor, courtesy Project Exploration.

Erin: Something else we had to consider, after deciding to add feathers, was how Raptorex’s skin looked—was it reptilian or more bird-like? I thought of Raptorex’s skin as a reptile skin transitioning into more of a bird-type skin—a flesh that was between getting rid of scales and turning into a rough, follicled skin. I ended up mimicking what vulture skin looks like: very rough, wrinkly, accordion-skin. It’s not super-soft as a chick’s would be. We also had to envision the oral margin, the withered reptilian lip, transitioning on top where the maxilla would have been.

Tyler: That’s another really interesting choice —when you look at things that are alive today that are either feathered or scaly, where you see things that are both feathery and scaly. For example, you look at the feet of a chicken, which are scaly; parts of a chicken that are feathered aren’t scaly. If you pluck a chicken or look at the zones of the chicken skin between the overlapping feathers that are bare, they don’t have scaly skin under there, they have this soft, almost-fleshy looking skin—bird skin. When we have to create a dinosaur that we’re going to put these proto-feathers on, are they growing out of scaly skin or out of this bird-like skin? This inevitably leads to the question of where do I end the scales? These are the questions that a paleoartist needs to ask him or herself: question every little detail of the model. If you get a chance to look at the Raptorex head up close, you can see the parts of the face that are scaly, as Erin was describing, and these areas kind of fade out into this more bird-like skin, which is where you see the proto-feathers. That’s an interesting little way that modern animals and all the reference material that they provide can be applied to these prehistoric life models to make them more accurate.

Q: It sounds like every step of recreating Raptorex—figuring out bodily girth, skin texture, and feathers—is a very involved process. What was the most challenging thing about creating Raptorex? What was the most difficult thing to come up with?

Erin: The most challenging thing for me is applying science to my art. Sculpting or painting, for me, is a no-brainer—I can kind of figure that out. For me, having to work the science in is difficult. A part of my difficulty came from the fact that I did not know what I was looking for, so I was constantly asking Tyler questions. And they were things that you wouldn’t think to ask until they came up, like as you’re putting things on. For instance, how thick is the skin on this part of the skull or part of the jaw? What are the holes in the skull doing and why are they there? Do you want to put a display structure on there and why would you put it there? I found myself working with Raptorex and coming up with dozens of questions; since Tyler has done a number of these flesh models before, he already knows some of the questions he will have to face and anticipates some of their answers. I, on the other hand, get stumped at points and have to rewind, look back through notes, download papers, and look for images. Everything I learned while working on Raptorex, though, has made some other flesh model-rendering projects easier for me. You ask many of the same questions, and because of your experience, you know where to go to look for answers.

Tyler: Because Erin wanted to get it right, it was extremely important to do the research and, anywhere possible, make sure that all the ideas, all the creative decisions, all the choices were really well-thought-out. In the end, it was really worth it for Erin to have gone through such a lengthy research process before even the true sculpture began. And the research process continues as the sculpture goes on—referencing and learning about the animal as you’re working on it. Since Erin finished Raptorex, she has done a number of other flesh models now over the intervening year since Raptorex has been done. With every one, there are the same kinds of challenges: you’re given something new and you start with a bone. However, these experiences do build on themselves. It’s become, I think, kind of fun to start a new reconstruction, do the research, learn about the animal, and figure out the answers to all these strange questions that most people never have to think about.

Raptorex flesh head prior to feather detail. Photo © Erin Fitzgerald and Tyler Keillor, courtesy Project Exploration.

Erin: I want to point out what I thought was the most fun part of creating this model: adding personal characteristics. I added a battle wound on the front of Raptorex’s nose, a claw mark that looks like it is festering, resembling what it would look like if an animal had to have the wound heal on its own. I also liked to think that as Raptorex was eating, its gums would get scarred. By adding your own personal touches, you can make a dinosaur look like it’s alive—fighting for its food, fighting other animals or something.

Tyler: Another cool thing that Project Exploration will have on the website is a time-lapse movie of Raptorex’s creation. Erin is also a photography enthusiast and has a lot of experience working with cameras and photography. When Paul had the idea to record the Raptorex sculpture process with a time-lapse, Erin largely figured out how to do that, positioning the camera, how to get that set up. That gave a really great opportunity, too, through the time-lapse—you can see the layers of clay going on over the top of the skull model. In a very interesting part of the video you can see the jaw open and close, where Erin was actually using the closure of the jaw to make sure that the lip line that she was sculpting created a true and efficient seal when the mouth was closed. Her sculpture has the mouth open—if you just sculpted that arbitrarily with the mouth open, you might not have a true, functional oral margin for the animal. So by closing the mouth and opening it again, Erin was able to test and refine and make sure that this thing, as accurately as possible, was depicting a real animal.

Erin: The time-lapse also shows my thought-pattern. You may see a couple of frames change back and forth—things get put on and taken off. The thought process changes—maybe something you look up changes what the dinosaur will look like in the end, so you add or remove something. We don’t just whip out a picture—it takes hours and hours of reading and looking things up.

Read more about Raptorex at Project Exploration’s web site.