Dino expert Dr Phil Manning found a Tyrannosaurus Rex footprint in an American desert where the monsters lived millions of years ago.
He joined Newsround to answer questions about the find - and what it's like to be a dinosaur hunter or palaeontologist.
How did you find the T Rex footprint?
It was like any find, a mixture of luck and judgement. It's luck because you have to be in the right place at the right time but also judgement because you choose places with the right rock formation and also use your experience.
So how exactly did a dinosaur footprint get left?
If you think about soft mud on the banks of a river and then an animal squishes it down it changes how it's formed. So in this case, because the mud had been compacted it became a hardened footprint and it's a few millimetres taller than the surrounding ground.
What did you think when you found it?
It was such an incredible find and I did a double take. Then I had a stupid grin that I couldn't take off for a couple of weeks.
What will happen to it now?
We're hoping to start excavating in the area next year or the year after but first we have to apply for permits and permission as it's against the law to just start digging. The fossil is hundreds of miles from anywhere so no one should interfere with it until we are able to return.
Why is this find so important?
It's important as there's only ever been one other footprint found and that was in New Mexico in 1993 but no bones were found nearby. We're hoping that when we go back we might find more footprints.
What is your favourite dinosaur and why?
My favourite at the moment is the Velociraptor as I have been studying them and also because they help us understand the evolution of the dinosaur and the link between dinosaurs and birds.
Were you interested in dinosaurs as a kid?
Yes I was. I found my first fossils in my garden in Somerset when I was about six and I found a sea dragon bone when I was about eight.
How do you become a palaeontologist?
The most important thing is to be really keen on dinosaurs. Do what you love doing and do what you're interested in, whether that's art or science or biology or chemistry as they all have bits of palaeontology in them.
The footprint found by Dr Manning
Do your best at school. You can also find out more about palaeontology at your local museum.
They might even have a group you could join as it's important to make sure you do things safely and properly.
Do you have to be clever?
Not really, some of the best dinosaur hunters haven't done much studying but they can find bones as they're really passionate about the subject.
Is it an exciting job?
You get to travel a lot and see parts of the world that few other people ever get to. Many of the dinosaur sites are in the true wilderness and the least populated areas such as deserts.
Where's the most exciting place you've been?
Patagonia is absolutely breathtaking and there's lots of unusual animals. As well as skunks and snakes they have giant rabbits. The scenery is pretty and there's some of the most untouched dinosaur hunting areas in the world.