Life is full of everyday miracles. The sort of things that are so unlikely to happen, it’s amazing they happen at all.
Take fossils for example. Let’s start with something big- a sauropod, or long-necked dinosaur. Should be easy to fossilize right?
Unfortunately we need a dead one for our fossil, so let’s skip the sad story.
Let’s just say an old brachiosaurus (Let’s call him old Mr. B) came to the riverbank for one last drink of water…Now we have a very large feast for scavengers all up and down the riverbank. They won’t have to worry about hunting for months! Well, maybe weeks, depending on how many critters are joining the buffet.
Mr. B is not going to stay in one piece. A leg over here…head gone…a chunk of tail in the belly of another…By the time the scavengers are done picking the bones clean, bits and pieces are going to be scattered and broken all over the riverbank.
That pile of bones bleaches in the sun for a few more months. The bones dry out and turn brittle. Insects and small, nocturnal mammals with ever-growing teeth gnaw on them.
The skies turn dark, storm clouds gather, and a week of constant rain raises the river. More rain from the north rushes in, and in a few short hours, flood waters pour in strong enough to uproot trees and toss huge rocks as easily as pebbles.
The rush of water and debris lifts the heavy bones and carries them downriver. A few ribs catch on the roots of a thick, strong tree, but the other bones are torn free and get carried on. A leg bone settles in a small undercurrent and sinks into a deeper spot in the river. The rest of the bones get carried on…
On and on, the skeleton is fragmented by the force of the water.
Silt- dirt and debris carried by the current- covers the bones.
Over time, enough layers of silt build up and are flattened by the layers above them. Water, pressure, and time cement the layers of silt into sedimentary rock like sandstone and mudstone.
Water seeps down through the rock. Bone is porous, and so water can seep through it. The water leaves mineral deposits behind, like the hard water deposits that build up in the dishwasher.
Like a sponge drenched in salt water and left to dry in the sun, the bones slowly harden like solid rock.
But that’s not all. It’s not enough to be fossilized. The rock needs to stay intact.
The earth is constantly moving. Rocks that hold fossils can be pushed down and melted in Earth’s liquid mantle. Or pushed up into mountains, only to be erased by wind and rain.
As if that wasn’t enough, we have to find these fossils. Exposed fossil bone erodes quickly in the face of wind, rain, and sun. Scientists usually have good ideas where to find fossils based on previous discoveries, but many times it’s the kid playing by the bluff who finds them. Or the hiker who sees that spot in the rock that doesn’t look like the rest…
Even when the fossil is found, it can be lost, destroyed, or stolen.
My point here is, it’s amazing we have any fossils at all! More amazing still, the exquisite beauty of fossils like the Lagerstatten of Germany and places like it. Just look at the archaeopteryx at the top of the paragraph here (those feathers are so perfect, they look better than my chickens’ feathers!).
I am truly humbled to think about the beauty of the world around us, of humanity, of life. That it’s possible to see remnants of creatures gone for millions of years. That we can even dream of what they might have looked like.
I look at a fossil like this, and I see a miracle. And then I look at the world today, see the people in my life…or even just take a moment to watch my hands and the way they move as I type these words…the complexity behind the mechanics of their movement.
An everyday miracle. 🙂
Fleshing Out the Bones Series:
- Part 1: The Miracle of Fossilization (the crazy hard obstacle course from death to museum)
- Part 2: The World’s Toughest Jigsaw Puzzle (making a mounted skeleton out of bits and pieces)
- Part 3: Here’s the Easy Part (figuring out muscle and other fun anatomy)
- Part 4: Let’s Put Some Skin on That (how much we know, and don’t know, about the soft stuff)
- Part 5: Time to Get Wild! (how we can guess about behavior, and how crazy it can get!)
- Part 6: Uncharted Waters (all about the big picture. No animal lives on a blank sheet of paper)
Pete's Paleo Petshop 
It’s sad but that’s just nurture’s way
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Wow. That’s a lot. How easy is it for something to be preserved in tar, as opposed to regular rock? Does the tar just turn into rock over time?
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Hi Brownie, good question!
Tar is awesome for preserving things in near perfect condition for thousands of years. No oxygen or bacteria to break things down. 🙂
Hmm, I’ll have to look it up for sure, but if I recall correctly there are at least a few tar pits still in liquid form.
The paleontologists scoop out the stuff and find the bones as they dig deeper. Pretty cool stuff 😀
But that’s for the Paleocene and such, the “age of mammals”. I don’t know a lot about it, but the pet shop will get there eventually! 🙂
I think any tar pit in the Mesezoic would’ve turned to rock by now.
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Ah, ok. 🙂 Is there still any calcium left in the bones by the time they uncover it?
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It depends on how the bone was fossilized.
In the example I have in the post it seems that there may be plenty of bone still left. Hard ground water fills the pores within the bone like a sponge, and leaves mineral deposits behind.
Sometimes this dissolves the bone or shell, but many times the mineral deposits just encase the bone. Like a sponge dipped in glue.
This is why some fossils are white and others can appear dark brown or black. The more white in the fossil the more original bone is still there. 🙂
There are some really cool fossils that have turned completely into opal, so it really depends on circumstances as to what happens. 🙂
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Why would someone steal a fossil?
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I truly don’y understand why people steal or destroy fossils, but unfortunately it happens. There are people in the world who would rather fill in dinosaur tracks with concrete rather than allow others to enjoy them.
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What I have always wanted to know is how do the paleontologists not get stuck in the tar
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From what little I’ve read or seen on this (since I’m not into the Pleistocene and such yet), paleontologists bale the tar out in buckets until they hit rock. Of course, as they dig down into the rock to find more bones, sometimes they have to bale out more tar as they go. It’s a very messy job that actually got featured on the show, Messy Jobs. 😀
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Oh ok thanks
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They avoided the tar completely by baling and digging
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Thanks for telling me that
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You’re welcome 🙂
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Messy jobs sounds like a dirty jobs spin-off or rip-off
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Yeah, they all look like it’d take a miracle to happen. It must be hard to weigh two things that are both so unlikely to take place!
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It’s harder to make a fossil than I first thought. Generally speaking, is it harder for something to become a fossil, or for something to be preserved long enough for us to find it? I guess it depends, right?
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Hi Michael! Thank you for stopping by 🙂
An animal or plant can only be fossilized in certain environments. Usually some place it can be buried quickly, like where water can push layers of silt over the remains.
Volcanic ash, sandstorms, and deep lakes with soft mud at the bottom are also good.
Nature is very good at recycling waste as soon as possible. Weather, specialized scavengers, and bacteria make short work of even dried out bones.
In short, though, I think it may depend in circumstances on which is harder. They all look pretty tough.
#1 get preserved before you are disintegrated
#2 stay intact as rock while rock around you gets pushed around and melted
#3 get found by someone before weather erases you
#4 avoid getting lost or destroyed by human hands long enough to get properly studied…
Whew, I think the first may be the biggest challenge. 🙂
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