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Thu July 3, 2014
The Dinosaurs In Your Backyard
We all know the story. Earth was hit by an asteroid 65 million years ago. As a result all the dinosaurs went extinct. Well, science works out problems using the best data available. But we never stop exploring, and we often find new evidence that can change our understanding. With that in mind...
Dinosaurs are still here. Not only that, they’re still incredibly successful.
Using evidence amassed over the past three decades, our story has been modified: Earth was hit by an asteroid 65 million years ago. As a result many species of dinosaur went extinct. Dr. Lindsay Zanno, Director of the Paleontology and Geology lab at the Museum of Natural Sciences in Raleigh, North Carolina and Research Assistant Professor in the Department of Biological Sciences, at NC State University spoke with us last week about a new species of Dinosaur. This week she’ll tell us about the dinosaurs in your own backyard.
Dinosaurs were a very specific group of animals. They went on and evolved into birds. There were birds flying around above the head of T-Rex. And then when the extinction came all the dinosaurs went extinct except for that one lineage. And so birds are themselves living breathing dinosaurs. Dinosaurs are still more diverse than any other group of invertebrates. They’re more diverse than frogs, than snakes, than lizards, than mammals; than any of those things. Almost everything we think is special to birds actually evolved first in non- bird dinosaurs. So things like how they breathed, the lightness of their bones, how they fold their wings, their three-toed foot, their rib cages, their feathers, the fact that they roost on their nests, these are all things we see in dinosaurs that are not birds. So, what we can do now is to reconstruct how you create a bird through the dinosaur family tree.
Evolution is not random. Basically stated, an animal is born with a mutation that helps it survive. The trait gets passed down until the descendants out-compete the original species. For some dinosaurs, feathers became a useful adaptation. But feathers evolved long before flight did. How come?
The hows and the whys are obviously the parts of science that are really hard to answer. When it comes to why feathers, we have a lot of hypotheses. One reason you might evolve feathers before flight is to keep warm. Another would be for display. The evolution of flight is another one of those great, on the horizon aspects of dinosaur science where we’re actively trying to figure out exactly how flight evolved and why. One of the interesting things that happened recently is the discovery of animals from China. There's this whole lost stage of evolution in the dinosaur family tree where animals had wings on their arms and their legs. Were trying to figure out, is this an intermediate stage and flight? Is this a separate evolutionary trajectory? Were these animals using forelimbs and hind limbs to glide and that led to powered flight? But again these are all questions that were figuring out as we go along.
Linking birds to dinosaurs is not just some wild guess. Science uses evidence; and we’ve got that covered.
We have non-bird dinosaurs that we actually have fossilized sitting on a nest of eggs and roosting just like a modern bird would; using their feathers coming off their arms to keep the nest warm. Sleeping dinosaurs that sleep just like a duck would at the side of a pond, with their necks twisted back in a heads up under their wing. We have parenting and reproductive behaviors and now we have soft tissue evidence in the forms of proteins that we’re pulling a dinosaur bones that are most closely aligned with bird proteins.
Soft tissue can’t be preserved for tens of millions of years, can it?
(read about soft tissue research by Mary Schweitzer, Dr. Zanno's colleague from NC State.) We didn’t think soft tissue could be preserved for that long and this is what's great about science. Sciences not dogma. We never stop learning and we never stop testing it's not as if somebody comes out of the hypothesis and then we go “okay great we got that figured out” and we move on. The job of the scientist is to always go back and retest those ideas and make sure that we didn't get it wrong in the first place. Or if there's more information to be gained. And soft tissue is one of those great examples.