What's Left to Discover?
Scientists know a lot about life in the Washington, D.C., area during the Early Cretaceous, but they would like to know more. We asked several Smithsonian scientists what questions they still have, and what new fossil discoveries would help them find the answers. Scroll down to read what they said, then find out what scientists do when new discoveries contradict the things they thought they already knew.
Do you have questions, too? Follow the link from the "Ask the Scientist" box to the right and tell us what this web site leaves you wondering about.
I would like to know what other Early Cretaceous ecosystems were like. It would help expand our view of the ecology of that time if we had fossils from more sites, especially from drier locations, to see whether they supported different plant and animal communities.
So far we have identified just a small percentage of all the animals that lived here, and for most we have only fragments. I would like to get a much better idea of how many species lived here, as well as what they looked like, and what their closest relatives were. For example, is the dromaeosaur the same as Deinonychus, from the western US, or more like the species in Europe, Asia, or South America?
I would like to know more about this early period in flowering plant evolution. What were the early angiosperms like, and how did they get a toe-hold in a landscape dominated by ferns and conifers? As we collect more plant fossils we may discover new species that help us answer these questions.
How many plant species lived in this ecosystem? By collecting a lot more plant fossils and paying attention to the rate at which we discover new species, we could estimate how many species remain undiscovered. This is a sampling technique that paleobiologists have learned from ecologists who study species diversity in modern ecosystems.
I am curious about the invertebrate organisms that lived in these swamps. Many insects, polychaetes (worms), crab and shrimp-like creatures live in the water, mud, and sand of modern wetland environments. Because these creatures don't have a hard shell like a clam or a snail, they decay quickly and don't have a good chance of becoming fossilized. If we get lucky, perhaps we will find a part of the ancient swamp that was rapidly buried, which would increase the likelihood that soft-bodied organisms were preserved there. Then we would be able to develop a richer picture of the aquatic ecosystem.
What happens when new discoveries contradict old ideas?
Whether they are trying to understand how dinosaurs evolved, what a particular species ate, or how fast it moved, scientists study all the available evidence and offer the best explanation that accounts for all their observations. A "good" scientific explanation allows other scientists to make predictions about what they will find when they examine new fossils or look more closely at old ones. If new observations match these predictions, the explanation is supported and strengthened.
Sometimes, though, new evidence contradicts old ideas. Then the old explanations must be modified, or even abandoned. Scientists find this exciting because interpretations that are supported by more complete evidence are more likely to be correct. In the future, if new fossil discoveries reveal errors in this painting, scientists and artists will work together to create a new and more accurate image.
We recently updated some of the dinosaur exhibit mounts at the Smithsonian to reflect new knowledge about the anatomy, stance, and movement of these species. For example, our Camptosaurus (CAMP-toe-SORE-us) displays were originally created before 1920, when the skull of this animal was poorly known and thought to have been long and rectangular. In addition, the arms were positioned far apart across the chest, and the legs were widely spaced. Since then, new discoveries have shown that the skull of Camptosaurus was shorter and had a more triangular snout. The arms are now placed closer together and the hands face palms-in -- this is because most dinosaurs could not rotate their hands far enough to turn their palms down (this outdated pose is commonly depicted). Finally, we placed the feet close together as well, reflecting what we have learned from footprints about their positions during walking.
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