Dinosaurs! (Or, How to Make a Fossil)

Guess who turns 30 this year? (No not me, that was last year.) It is the Royal Tyrrell Museum. (Pronounced TEER-uhl not tie-RELL) Now, 30 years old might not sound that impressive when you are showcasing exhibits that can boast 30 MILLION years old but none-the-less, still a pretty big deal.

The Royal Tyrrell Museum is nestled down in Alberta’s badlands, in the lovely City of Drumheller. You go from the beautiful canola covered prairies and end up in the desert, where a very different geological landscape awaits you. What makes the Royal Tyrrell Museum one of Canada’s treasures is that it is THE Dinosaur Museum. And who doesn’t love dinosaurs? Seriously, to say you don’t love dinosaurs, weren’t completely fascinated by them as a kid, don’t have a kid that isn’t fascinated by them, and don’t find them remotely interesting now, you are either lying or have no sense of whimsy. Dinosaurs are awesome-that is why Jurassic World it all its terrible-ness still made money hand over fist: dinosaurs are awesome.

And on the other side is a lush prairie field.

And on the other side is a lush prairie field.

For me (and my fiancé), going to the Royal Tyrrell Museum is like being a kid in a proverbial, allbeit science-themed, candy store. Exploring the world, not as we know it, but starting from over 570 million years ago in the precambrian period. What other place can you go where you can you travel in time, going from the Permian, to the Triassic, round a corner, end up in the Jurassic period, walk a little further on and hit the Cretaceous period, see a mass extinction event (one that wasn’t influenced by human activity nor threatens your current safety) and live to see the Rise of the Mammals?

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Dimetrodons from the Permian period.

Stegasaurous (my personal favourite) from the Jurassic period.

Stegasaurous (my personal favourite) from the Jurassic period.

Triceratops from the Cretaceous period.

Triceratops from the Cretaceous period.

Just another thing that makes Alberta a pretty special place to live is the fact that it seems the land in which we now call Alberta was once a hot bed (now fossil bed) for dinosaurs. This shouldn’t be a huge surprise, considering that our economy is oil-based. Petroleum hydrocarbons are what happens to plants and animals millions of years and thousands of tonnes of pressure after they die. What is surprising to me is that we are able to find so many dinosaur fossils at all. What we dig out of the ground are not animals that existed 10s to 100s of millions of years ago themselves, but rather pieces of those animals (and plants) that just happened to die under just the right conditions where their decay wasn’t stunted and they were then turned to stone. This becomes even more remarkable when we are able to find evidence of soft tissues.

So let’s take  a look at how to make a fossil:

The first thing that has to happen is that the animal has to die. Now when you die, there are lots of things that happen. There are always scavengers that are looking for a quick meal. There are also bacteria that start breaking down all of the organic matter through a bunch of biochemical reactions. Then there is the environment: wind, rain, fire, it can all affect the body of a decaying organism. But I haven’t told you anything that you didn’t already know: animals die, their bodies decay. That process doesn’t necessarily lead to fossilisation. To make a fossil, the carcass needs to be buried, and pretty quickly, before too many things have eaten it or capricious weather has destroyed the remains. Now, the speed at which an animal needs to be buried depends on environmental factors such as humidity and temperature. The key is for the animal to be buried before too much of the carcass, specifically bone, is destroyed by the natural degradation processes.

The skeleton known as

The skeleton known as “Black Beauty” at the Royal Tyrrell Museum. The bones of this T-rex are a striking black. This is due to manganese being incorporated into the skeleton during fossilisation.

Now that we have buried the carcass, the bacteria, naturally present, get to work. Animal bones are not inert, hard structures that our bodies hang off of. Bones are a matrix of living organic tissue where the mineral hydroxyapatite has been grafted up around it. Hydroxyapatite is a mineral comprised of calcium and phosphate ions. Over time and under pressure, the hydroxyapatite can change, incorporating ions from the surrounding sediment, such as iron, uranium, even (rarely) manganese. The biggest change, however, comes from the bacteria “eating” the organic part of the bone. As these bacteria metabolise the organic material from the bone, the produce mineral by products, depositing these minerals into the spaces of the bones previously occupied by the organic matter. The most common mineral deposited is calcium carbonate. The bacteria use calcium ions from the surrounding water and sediment to capture the carbon dioxide that is produced as waste product of their metabolism. Calcium carbonate is better known as limestone. The bacteria may also incorporate other ions, like iron, into these mineral deposits. After many years, the bacteria will have successfully transformed bone into stone.

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When I think about this process, how an animal has to die, be buried quick enough and deep enough that degradation processes don’t completely destroy the skeleton, I can help but be amazed that we even have fossils, let alone the stunning array of fossils that we do have. We have managed to piece together some pretty amazing details about the life on earth millions of years ago. This has allowed us to take a glimpse into our own evolution. This is what the science of palaeontology gives us: a passport into the past, a pastport if you will. So if you have ever wanted to travel back in time, I encourage you to visit the Royal Tyrrell Museum.

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