Don't look now, but there are dinosaurs in your backyard.
It's nothing to call Animal Services about; there are no Triceratops snacking on the shrubbery, no Velociraptors about to make off with the cat. If you're worried about mollifying them, a little birdseed should do the trick. Because all we're really talking about are birds -- wrens, starlings, pigeons, even the first robins of spring.
Dinosaurs, every one.
Or so goes current scientific thinking, anyway. According to evolutionary biologists, birds are the direct descendants of saurischian dinosaurs -- living vestiges of an age when T. Rex wasn't just an old English rock act. But even though the bird-dinosaur connection is widely known and accepted, it remains hard to see, because we don't tend to think of dinosaurs as having feathers or being small or migrating south for the winter.
Feathered Dinosaurs and the Origins of Flight, currently on display at the Royal Ontario Museum in Toronto, helps on at least the first two points. Built around 125-million-year-old fossils -- many of creatures the size of chickens -- found recently in Liaoning Province in China, it provides proof that some dinosaurs had feathers, while illuminating the anatomical changes that went into the evolution of flight.
Because the Liaoning specimens were captured in fine volcanic silt, they're not just the jumble of bones usually associated with fossil finds. In addition to bones, there are also impressions of softer tissue, including feathers and in some instances beaks. Among the more eye-opening specimens on display are the very feathery Confuciusornis sanctus -- which definitely looks more like a bird than a dinosaur -- and a Pterorhynchus so well-preserved that it's possible to see not only its feather follicles and head crest, but to get a sense of what its colouring was like. (There's also a beautifully rendered model showing what the creature would have looked like in action.) But it isn't quite so simple as seeing is believing, because it isn't always obvious what, precisely, is being shown.
As Mark Engstrom, vice-president for collections and research at the ROM, admits, "the problem, in part, is that the fossils, because they were preserved in a lakebed, are more two-dimensional than three in some cases." So instead of the towering skeletons usually associated with dinosaur exhibits, gallerygoers are frequently faced with what look like abstract bas-reliefs barely a metre long. Some are quite beautiful -- there's a fish fossil plate containing a Protopsephurus liui and a small Lycoptera that could almost pass for a woodblock print -- but it takes a bit of explaining to see how this evidence adds up to proof of the bird/dinosaur connection.
That's why the ROM exhibit includes a second, locally generated component tracing the anatomical changes that occurred as dinosaurs evolved into birds.
"Some of the characteristics are hard to see," Engstrom says.
"There's a confusion about bird-hipped and lizard-hipped dinosaurs, which is a big division in dinosaurs. In fact, birds are related to lizard-hipped dinosaurs, not bird-hipped dinosaurs -- which is something that can get complicated in a hurry."
Fortunately, the second half of the ROM display makes the issue less confusing by using three-dimensional fossils with big signs clearly pointing out the bones in question. "If you want to understand what indicated dinosaurs were related to birds, there were a number of characteristics that indicated that, and it's easy to talk about them," says Engstrom. "But if you don't really point them out, nobody gets it."
In that sense, Feathered Dinosaurs is a bit of a balancing act. On the one hand, it presents some of the hottest new evidence in paleontology, which makes it of natural interest to dinosaur-obsessed children. But at the same time, the ideas at the exhibition's heart are about evolutionary biology, a topic even grownups find intellectually daunting. There are concessions made for both groups -- big, 3-D dinosaurs to balance out the smaller, flatter Liaoning fossils, pronunciation keys for Scansoriopteryx and Psittacosaurus on the display cards so that, as Engstrom jokes, parents can read them "and not get corrected by their kids" -- but no stinting on the larger scientific issues.
"The exhibit is really about pattern," he says. "This is a particular example of evolution of a group. It's been known for over 100 years that birds were in some way related to dinosaurs. But we really worked out the exact relationships by having these Liaoning fossils. They've given us so many more clues about anatomy and intermediary forms -- they were the right fossils at the right time."
Nor is the Liaoning find likely to be the last word. As Engstrom notes, there has been a tremendous amount of progress in paleobiology over the last four decades, thanks to new ways of examining the fossil record as well as new discoveries. In fact, about the same time the ROM show opened, an article in Nature reported on a Tyrannosaurus rex bone found in Montana that included soft tissue that had not fossilized. Already, scientists have noted similarities between T. rex blood vessels and those of ostriches, but there may be even bigger news should researchers be able to extract DNA from the tissue.
"I thought people missed the significance of that," says Engstrom.
"The article I saw was in The New York Times, and they were talking about going back to the Jurassic Park thing and cloning dinosaurs. And that's not going to happen. But what's really exciting about that is, if it actually is tissue and not remineralized, there actually is the possibility of getting some DNA out of that, and placing the DNA sequence in the context of the evolution of the whole group."
Feathered Dinosaurs and the Origins of Flight continues at the Royal Ontario Museum in Toronto until Sept. 5.Report Typo/Error
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