Premise 1: "If these bones really were millions of years old, then the blood cells and hemoglobin would have totally disintegrated."
Premise 2: But blood samples from dinosaurs have been recovered.
Conclusion: Therefore, dinosaurs did not live millions of years ago but thousands.
This has become such a popular argument within the young-earth community that the Answers in Genesis creation museum has an entire exhibit devoted to it. (Scroll toward the bottom of the page for a description of the exhibit and its purpose.)
My friend Greg Moore has fully documented the on-going saga of this controversy in his series of papers listed in the right sidebar (under "Articles & Online Books").
But now, the issue has gotten a little more sticky. A couple weeks ago, yet another study came out reanalyzing - and possibly rebutting - the validity of the original data.
"Scientists question dinosaur soft tissue find"
More studies will need to be done in order to determine which finding is correct. But if the supposed dinosaur blood sample turns out to, in fact, be bacteria (due to contamination), then the whole infrastructure of that young-earth argument will collapse. (Wonder if AiG will update its exhibit if that happens...)
Dr. Fuz Rana has a stellar discussion of this issue on the July 31, 2008 Science News Flash podcast. In fact, it should be must-listening for all students. It is an outstanding illustration of self-correcting nature of the scientific method and why Christians can trust the findings of so-called "secular" science.