Historically, Dodson contends, dinosaur discovery was largely in the hands of British, Canadian and American researchers, with few exceptions in other countries. In recent decades, however, the discovery of new fossil beds, especially in China and Mongolia, has resulted in a greater diversity among dinosaur researchers.
Ultimately, however, there are only so many dinosaurs that can be found. Fossilization itself is a rare event, and there are very few places on Earth, as a whole, where the rocks are of the right age to contain fossils dating back to the dinosaur era. At some point, paleontologists will find all the fossils that could possibly be found.
Dodson and Wang's analysis also offers evidence that dinosaur populations were stable before the extinction event that ended their reign of global dominance. Dodson, however, warns that the picture of the fossil record at the time of extinction is not resolved enough to say definitively.
"We have enough information to say for certain that, within six million years of the meteorite's arrival, dinosaur populations were stable," Dodson said. "But we don't know for certain if there was a decline within that six-million-year slice of time before the extinction event."
Their estimates for total dinosaur diversity take into account the number of dinosaurs already found, the rate of discovery and potential richness of the fossil locations that can be reasonably explored. They hold that it is still an open question as to whether their estimates of discoverable genera mirror the actual diversity of dinosaur genera that walked the earth. Their findings, combined with previous studies suggest that
Source:University of Pennsylvania