Salt Lake City based author Brian Switek wrote the recently released book, My Beloved Brontosaurus, to explain why our perceptions of dinosaurs have changed dramatically over the past 20 years. Gone is the imagery of scaly, slothful animals, replaced by dynamic, and sometimes feathered creatures. Modern paleontology is gleaning from fossils more details about dinosaur lives than ever before. Switek spoke with Explore Utah Science contributor Julie Kiefer.
JULIE KIEFER: What were you hoping to accomplish by writing, My Beloved Brontosaurus?
BRIAN SWITEK: There is always a lag between scientific discoveries and how science permeates public perceptions. I wanted to explain the current knowledge about dinosaurs by highlighting the tension between what scientists know and what the public knows.
Jurassic Park, which first came out 20 years ago, gave this idea that dinosaurs are very scaly and relatively drab. Now that the fourth movie is coming out, this is during a time when we know that many dinosaurs, like the Velociraptor, that are closely related to birds, were covered with feathers and fuzz and were relatively striking in color. It’s kind of a disappointment to hear the film director say there’s going to be no feathers in the next movie because fans prefer the old scaly way. I’m trying to make the case that dinosaurs are cooler than they’ve ever been.
JULIE KIEFER: How do scientists know that some dinosaurs had feathers?
BRIAN SWITEK: In China, there are many dinosaurs preserved with feathers intact, and there are also dinosaur feathers preserved in amber. Also on arm bones of the Velociraptor there are little bumps called quill knobs. You see the same thing on the arm bones of the turkey vulture. Those are where the pen-like attachment for some of the long wing feathers go. Even though the Velociraptor couldn’t fly, based on the skeletal evidence, it had pretty advanced plumage.
If you look at the evolutionary tree, there is a particular group of dinosaurs called the coelurosaurs that birds belong to as well. Every lineage within this group had some sort of fluff or feathers or fuzz in it, suggesting this is a common trait for this group. Even though no one has found direct evidence of feathers on Tyrannosaurus rex, it’s a good bet that they probably did have some kind of feathery body covering because it’s a coelurosaur.
JULIE KIEFER: What else is new research telling us about how dinosaurs looked?
BRIAN SWITEK: As a kid I was told we would never know what color dinosaurs are, and now paleontologists are starting to figure that out. I mentioned that some dinosaurs are preserved with feathers. If you take something like a scanning electron micron microscope and zoom in on them, you’ll see little blobs. They’re in certain shapes and arranged in a certain density. A paleontologist figured out that these were melonosomes, pigment carrying bodies that are also in the feathers of birds.
Some colors like browns, reds, blacks and greys are made by a reaction from light bouncing off structures in the feathers. If you have these structures in fossils, and you can look at the feathers in modern birds where you know what the color is, and match up the patterns of melonosome shape and distribution, then you can reverse engineer what color that dinosaur feather would’ve been. The first one to be fully reconstructed was a pigeon-sized dinosaur, called Anchiornis. It kind of looked like a magpie. It was mostly black with some white on the feathers, and a slash of red feathers on top of its head.
The ability to know dinosaur color creates all sorts of opportunities. If you have a big enough sample size and reconstruct the colors of many animals, maybe we can figure out whether some animals died with their breeding plumage on, or if there are color differences between males and females. I’m totally fascinated to see where this goes.
JULIE KIEFER: Are there ways to learn about how dinosaurs lived their daily lives?
BRIAN SWITEK: Yes, but they’re not always the most direct. A dinosaur trackway is recorded behavior. It’s an actual few moments in an animal’s life where you can see what direction it was moving, how quickly it was moving, and interactions between dinosaurs.
There is also evidence from bone pathologies. Paleontologist Andy Farke took models of Triceratops skulls and said, ok if these animals are really locking horns, what positions would actually work? Based upon that he went back to fossil skulls and found lesions and other damage right where the models predicted. That’s pretty decent evidence that these animals were actually locking horns and fighting each other.
JULIE KIEFER: You conjure some interesting mental imagery when you write about dinosaur sex. You write, “I envisioned a pair of amorous Brachiosaurus … each one waiting for the other to make the first move. But try as I might, I couldn't quite figure out the mechanics of what should come next.” Why take on this topic?
BRIAN SWITEK: It may seem like a silly topic, but I wrote about it because it’s important in dinosaur lives. In the book, I present an anecdote that helped show that we put our own values into our study of sex and mating in nature. In the early 20th century, naturalists on an Antarctic expedition observed sexual behavior among Adélie penguins that was considered out of the norm. That section of the report was taken out of the final monograph that was published. It was a century before this document with important, original observations was rediscovered.
Beyond the taboos, for a long time for dinosaurs it seemed like an ancillary topic that almost anyone could speculate on because there was almost nothing substantial to be said. Now that is changing.
It has only been recently that we’ve been able to tell what sex dinosaurs are. We’ve found females that happened to be laying eggs when they died. They have a special kind of bone tissue inside their long bones that we can identify.
In terms of sexual behavior, we can’t observe dinosaurs trying to woo each other, but we can use other methods. We are using evolutionary logic and looking to birds and crocodiles. By seeing what they share in common, we can deduce what might have been present in a dinosaur’s physical anatomy. New fossil evidence has also helped. There are hips of female dinosaurs that still contain eggs in it. The number of eggs and their position tell us something about the reproductive anatomy.
JULIE KIEFER: Besides reading and writing about paleontology, how do you satisfy your dinosaur cravings?
BRIAN SWITEK: I volunteer at the Natural History Museum of Utah, and during the summer months I go out into the field with them as often as I can. It’s fantastic to be looking for scraps of teeth, or tracks, or something that someone has never seen before that will lead to a new understanding of dinosaurs and prehistoric life.
JULIE KIEFER: Where is your favorite place to go fossil hunting?
BRIAN SWITEK: My favorite place in terms of visual beauty is Dinosaur National Monument on the Utah/Colorado border. It contains more exposures of different teleological periods than any other national park. You can stand in some places and see oceans going in and going out, replaced by deserts, replaced by flood plains, and another ocean comes in and recedes. You can see millions and millions of years of history just laid out in front of you.
Brian Switek also authors the National Geographic blog, Lealaps.