Dinosaur expert finding the past is a window to Earth’s future
URI’s dinosaur expert plus colleagues elsewhere in the country are on the verge of a discovery that may cast light on environmental conditions that may exist 100 years from now.
The discovery is linked to research being done in some fossil beds in Arizona.
Up until recently, says Dr. David Fastovsky, it was believed that the earliest dinosaurs first appeared in what is known today as Argentina and then spread out across the ancient landscape.
But recently developed dating methods have led the scientists to realize that South America had nothing on North America when it comes to being the birthplace of the earliest dinosaurs.
Fastovsky and colleagues at Baylor, MIT, Southern Alabama and the University of Kansas, using high-precision Uranium-Lead dating, are learning that ancient river deposits in the Petrified Forest National Park, containing dinosaurs, may be as old as the beds in Argentina.
“So dinosaur evolution, instead of being this slow process in South America and then spreading all over the world, looks like it boomed in North American and South America at very close to the same time,” says Fastovsky. “The old story was that there was a slow radiation of dinosaurs all over the world but now it looks like it was a lot faster,” he added.
The new dating techniques, he explains, also gave the researchers new dates as to when there were faunal turnovers—i.e., when one group of animals died out and when another started to evolve.
Now, he and his colleagues are attempting to tie these faunal turnovers to climate and environmental changes.
“The conditions after the faunal turnover are very similar in terms of mean annual temperature and in carbon dioxide in the air to the conditions that are predicted by climate models for the year 2100. We have been saying for many years we know what the earth does during global warming because we have seen it in the past, but we don’t always have well-controlled, ancient analogs. This is the first example I can think of where we have the right climate variables. We also have a faunal change so we can monitor the reaction of the ecosystem to physical paleoenvironmental changes. So we see this as a really exciting ancient analogy for modern climate change on the earth.”
Fastovsky and his colleagues are in the process of drafting a NSF application to fund more research.
The whole project hinges on the dating techniques used by MIT scientists. “It all starts with getting precise dates and once you get them, the sky’s the limit,” says Fastovsky.
The technique, involving the preparation of crystals of zircon in which the uranium is enclosed, allows the researchers to determine the relationship of the different rock units in time. The rock units contain ancient soils and those soils responded to the climate at that time. Among the things that can be determined from the ancient soils is the amount of carbon dioxide in the atmosphere at the time the soils were deposited.
“One of the key climate variables we are looking at is the amount of carbon dioxide in the atmosphere and mean annual temperature, and those two quantities have been predicted for the future global climate change. Our numbers and the predicted model numbers appear to coincide around the year 2100.
“So for us, that’s pretty exciting!”