Dinosaur Trips guests go behind-the-scenes in the fossil lab at the Philip J. Currie Dinosaur Museum in Alberta
Just a little reminder that Intro to Dino 101 is where we get back to the dinosaur basics. Or, for many of us, get to the basics for the first time. This time out we’re talking fossils.
More specifically we’re looking at how prehistoric creatures turn into fossils.
How Are Dinosaur Fossils Made?
So, when animals, plants, or whatever else roamed this earth meets their end, most of the time, they disappear—decaying into the dirt, lost to time. But once in a while, the universe gets creative. The conditions align just right, and instead of fading away, these creatures are preserved—turned into fossils. Little time capsules from a world we’ll never fully know, but we can try to piece together.
Now, there’s more than one way to fossilize. If you’re lucky—or unlucky, depending on how you see it—you might end up frozen, dried out, or trapped in tar or resin, becoming a whole-body fossil. These are like snapshots from a lost age, showing us exactly what the organism looked like in life. But don’t hold your breath—these are rare, the jackpot of the fossil world.
Most of the time, though, it’s heat and pressure that do the trick. Bury a plant, fish, or some poor reptile in sediment, and their tissues start to break down. Hydrogen and oxygen make their exit, leaving a carbon imprint behind—what we call carbonization. Think of it as nature’s Polaroid, capturing a detailed silhouette of life long gone.
Then there’s permineralization, or petrification—the bread and butter of fossil-making. After the soft tissue decomposes, the bones stick around. Water flows in, carrying minerals that fill every crack and crevice. Over time, those minerals harden, turning bones into stone, trapping the past in a shell of rock.
Sometimes, water plays a more aggressive game. It dissolves the original hard parts of an organism completely, replacing them with new minerals. That’s replacement—creating a fossil that’s a mineral clone of the original creature.
Molds and casts? They’re part of the fossil world’s supporting cast. Pardon the pun. When an organism dissolves, it can leave behind a mold—an imprint of its exterior in the surrounding rock. Fill that mold with minerals, and you’ve got a cast. And if sediments fill an internal cavity like a shell or skull, you get an internal mold. Each of these fossils is like a tiny message in a bottle, telling us just a fraction of the story of a world that came before. And it’s up to us to listen.