Outline the method for dating rocks and fossils using radioisotopes
You can also check them against each other and make sure your answer makes sense.
Igneous rocks (ones that form when magma comes out of the Earth's core and hardens into rock -- like basalt, granite, and pumice) also can contain radioactive samples of nonbiological origin, that likewise become a ticking clock once the rock hardens and stops stirring itself into the rest of the Earth's molten core.
The earliest birds appear after dinosaurs but before modern birds. In fact, “out-of-sequence” fossils are found routinely.
We see ancestral birds spanning the gap between their own landlubber ancestors and fully modern whales. We have already discussed the discovery of tetrapod tracks 20 million years prior to the presumed intermediate fossil linking fish and amphibians. The prevalence of out-of-sequence fossils in the geologic record has led to the regular invocation of “ghost lineages” — see Paul Nelson’s posts here and here for further discussion.
So, where this comes in for rocks is that the carbon in living organisms tends to get replenished with fresh (mildly) radioactive carbon and oxygen, matching roughly the abundance in the air and water surrounding the organism, until they die.
This is why scientists use a bunch of different elements for radioisotope dating, because each of them is good at measuring a different length of time.
I will review Coyne’s Chapter 3 in a subsequent article.