So why the date of 65 (or 67) million years?2 Hoganson explained, “[The Badlands are] one of the few places in the world where you can actually see the boundary line where the dinosaurs became extinct, the time boundary. In the Badlands, this layer is exposed in certain places.” Hoganson is referring to the K–T extinction boundary, which allegedly divides the Cretaceous Period from the Tertiary Period in the fossil record and marks the extinction of the dinosaurs. Thus, the team must date the find as at least 65 million years old—despite any evidence otherwise—just so it lines up with evolutionary theory and the uniformitarian understanding of the fossil record.
That "uniformitarian understanding" is based on particle physics that has been known for at least a century and has withstood literally thousands (if not hundred of thousands) of direct tests. Scientists aren't "assuming" the age of the fossil any more than you are "assuming" that I was born more than ten and less than two hundred years ago.
That said, we find a few flaws in assigning this date to Dakota—and it’s important to remember that that’s what scientists do: assign dates based on circumstantial evidence. Fossils don’t come stamped with exact dates!3
Depends on what you mean by "exact" -- creationist blustering about the ineffectiveness of radiometric dating is so overblown as to be ridiculous.
The scientists explain how Dakota must have been “buried rapidly.” That is exactly the explanation creation scientists give, but we have a clear, global explanation for the millions of fossils we have, which are time and time again shown to have been buried rapidly and catastrophically: the Flood of Noah’s day, which unleashed catastrophes worldwide and covered the world in water for a year. Starting from this viewpoint, we can make sense of these many fossils buried rapidly and recently—just a few thousand years ago.
Making shit up is so much easier than actually trying to understand the world, isn't it? And scientists do have a clear explanation for why so many fossils are buried relatively rapidly -- if they weren't buried rapidly, we wouldn't find them at all, or at least not at that level of preservation. It's a form of the anthropic principle.
Ultimately, this news shows us once again that science is beholden to one’s worldview. In this case, as in many, the old ages required by the fossil record—which are in turn required by the time line evolutionary theory needs—dictate the dating of the fossil. Starting from Scripture, we have the answers that explain why we find millions of fossils laid down catastrophically in rock layers all over the earth: the global Flood that the Bible describes.
I'm not going to bother detailing them, but anyone who isn't familiar with these issues should head on over to talkorigins.org to check out all of the scientific problems with a global flood. When Larry Moran wrote his post on people being fractally wrong, this is what he was talking about.