 The fossil record provides incredible evidence of evolutionary processes. There's a couple of ways that this happens. First of all, the principle of superposition basically says that in a rock, I don't know, like you've been places where you've seen lines of rock in rock that is visible because of a slice or a canyon or whatever. And each of those layers, it makes sense that the deeper the layer is, the older that piece of rock is. Because it makes sense that newer stuff would be laid down on top. In fact, then you can see all sorts of really interesting geological processes, like this, whatever happened here, where we actually had a literal tilting of the earth. And you can see the lines and then the stuff that got laid down on top of it. And again, it makes sense that what's deeper is going to be older. Now, what they've done is they've looked at the fossils that they find, like these, there's extinct critters. Like, we don't have these things anymore, and we don't have trilobites anymore or crinoids anymore. And so they look at these fossils of critters that no longer exist. And then they look at where they are in the rock layers. And they find that, for example, the trilobites are in the deepest, oldest layers of rock. And they've found that if they go to another place on the planet, like a whole other location, trilobites are found in that layer of time in the rocks, which indicates that they're older than the other things. Now, that makes sense, this idea that the deeper things are, the older they are, but that has actually been confirmed by looking at half-lifes of radioactive isotopes that exist in all the stuff all around us all the time. And they've got ways of counting radioactive isotopes in rocks or artifacts or even, like, dead bodies. And they can see how much decay has happened, and they know how quickly the decay should happen. And so, for example, if they're checking for carbon-14, they know that they know the amount of carbon-14 that should be in the atmosphere so should be in the critter originally. They know that after 5,700 years, half of that carbon-14 will decay to carbon-12. Remember isotopes? They're just unstable and they turn back into their more stable form. So, carbon-14 will decay to carbon-12. Half of it will decay to carbon-12 after 5,700 years. They know how much carbon-14 is in a living sample of critter, and then they can count up how much is left and know how much time has passed from when that thing died. This is kind of a bizarre concept. It's a little bit conceptually challenging, I think, but they basically have a whole slew of radioactive isotopes that will decay over time and they have various amounts of time that it takes them to decay. So, using all of these different radioactive isotopes, you can actually figure out how old something is, how old a rock is based on how much uranium-235 is in there and how much lead-207 is in there. You can figure out how old it is. This concept is how we check the dates, but the superposition is kind of an easier way to conceptualize that. What we've found is that more primitive fossils are deeper and older. So, we see through the fossil record that there has been speciation over time. Now, that's one piece of evidence that evolution has that we've had macroevolution happening on our planet for a long time. Here's more.