Fossil facts: 5 unique finds – and how scientists figure out their age

At Stump Cross Caverns, we love fossils and think you will too. They are beautiful things – little time capsules that tell stories of a mysterious prehistoric age.

Not sure if you do love fossils? Well, let us tell you about some of the coolest fossil finds and how scientists use them to learn about our past.

We're sure you'll soon catch the bug too. (Get it? Fossilised bugs? Never mind…)

Fossil facts: the basics

You can think of a fossil as a stone that once was a seed. Amazing, right?

Those ordinary-looking rocks contain creatures that were once growing and changing and shifting. Now they're frozen in time and made solid, ready for us to learn about their lives and the unfamiliar world they inhabited.

Fossils can be tiny

The smallest dinosaur or lizard fossil found so far is an example of an Oculudentavis khaungraae. This was a tiny beast – smaller than a fingertip – with 100 teeth and a bird-like skull. The fossil was discovered in Myanmar, frozen in amber for millions of years.

Fossils can also be huge

The biggest dinosaur fossil discovered so far is the Patagotitan mayorum, found by a sheep farmer in Patagonia. This enormous beast may have been the biggest dinosaur ever. It weighed 70 tons – the same as ten African elephants.

Five of the weirdest fossil finds ever

Tiny beasts or ginormous monsters not your thing? Don't worry, fossils can be very strange too. Here are five of the weirdest things found captured in rock.

1. A giant ant

Titanomyrma was as big as a hummingbird – and would definitely have stolen your sugar cubes. Four fossils of this ant have been found, spread out across the globe.

2. A pregnant sea monster

That's right! An example of Dinocephalosaurus was found with an embryo inside, confirming that this beastie gave birth to live young. A marine reptile, Dinocephalosaurus looked not unlike the often-reported sightings of Nessie at Loch Ness.

3. A beach-ball frog

Actually, it's called Beelzebufo – and is popularly known as the "devil frog" or "frog from hell". Creepy!

Anyway, this colossal croaker was the size of a beach ball. Imagine that bouncing into your ice cream cone on a windy holiday…

4. A spider attack

This kind of fossil is so rare that only one has ever been found: a spider, frozen in amber, grabbing itself a wasp-shaped snack.

5. A beaver trapped by an avalanche

This grizzly 30-million-year-old fossil was found in Montana.

How do we know the age of fossils?

Stump Cross Caverns is a place to time-travel – to wander back through the ages to see the magic of ancient living things made solid in rock. Old things. Really old.

But how do we know how old?

There are a few ways to find the date a fossil began its life in rock. We're going to tell you about three of them.

1. It's sedimentary, dear Watson

Like the famous detective Sherlock Holmes, we can look at the evidence in the dirt and ground around the fossil. Drawing from what we already know about geology, we can use this to make a wise guess about the fossil's age.

2. Layers like a sandwich

Sometimes, we look at the layers above and below the fossil. Often the things above a fossil are younger, and the things that it sits on are older.

3. Cosmic rays from the sun

Honestly, this is a real technique!

Scientists use a method called radiocarbon dating, which helps them find out how old very old things are. They do this by measuring the carbon-14 inside the fossil at the time it died. This number tells us its age.

And here's the incredible bit: carbon-14 comes from ancient cosmic rays emitted by the sun. Wow!

The fossil whisperer

Of course, exploring these fossils would be even better if we had a guide – someone to take us on a journey through time who knows the stories inside these mysterious stones.

Good news. We do have a guide: the Stump Cross Cavewoman!