BBC reporter Jacey Normand travelled to the Badlands of Montana, US, in July. She accompanied Manchester palaeontologist Dr Phil Manning in his quest to find a preserved footprint left by the dinosaur T. rex.
A dinosaur walked this way 67 million years ago
To recognise a dino print a good place to start is by examining the bones of the real thing.
The closest most of us ever get to that is via casts, like the one at the University of Manchester's Museum.
Its 3.5m (12ft) T. rex model resides with other bones and information. The beast is like a watchful guardian over the whole collection.
The university's head palaeo-scientist, Dr Phil Manning, points out the enormous size of the animal's feet and explains how, "footprints are just like the shoes which fit the foot".
But this T. rex is only a model, the real "Stan" (as he's called after being excavated back in 1992 by amateur palaeontologist Stan Sacrison) is on display in South Dakota, at the Black Hill's Institute which seems like the best place to begin our journey.
Seeing the real Stan for the first time is a mind-blowing experience.
His claws look so delicate yet viciously powerful, his teeth are like throwing knives; and in the back of his skull, a hole made by what appears to be another T. rex tooth, a bite perhaps sustained during battle - an injury he survived, a marker of his resilience.
Ask anyone out in these Badlands if they have a dinosaur story and they all do.
Amateur digging and chatting about bones makes palaeontology a part of their lives.
These people accept their heritage; they still live amongst it. Get invited into their house for coffee and you'll soon be looking at prehistoric teeth, femurs, even jaw bones.
An excitement money cannot buy and for which words cannot do justice
So it is perhaps no surprise that after a four-hour drive (50km of which is entirely off road) we're summoned to a ranch because the owner believes she has T. rex prints out back.
After careful inspection, Dr Manning is not convinced. They look very similar and as a find are significant, but a few characteristics rule them out as our "shoes" - and our quest continues.
Dr Manning knows what he is looking for. With an international profile and a career spent excavating dino tracks, he is 70% certain that some of the footprints he looked at last summer are the real thing.
He finds his way round this arid landscape like a human sat-nav, even knowing the areas we can pull in to discover our own fossil bones.
I pick up my first one, part of the shell from a prehistoric turtle. This is one of those moments you only ever experience two or three times in your life. An excitement money cannot buy and for which words cannot do justice.
I am suddenly on a roll and quickly start identifying other bones as well as recognising the difference between bone and rock (they can look quite similar).
There's no shortage of bone either but surprisingly much of it is entirely worthless. It sits in the middle of nowhere, weathering away. This could be the real tragedy but then the land is so vast, treacherously dripping with rattle snakes and scorpions, making the risks of combing every inch of it an impossible task.
As our evidence builds, we enter the climax of our journey - the site Dr Manning believes is harbouring T. rex tracks.
We drive for six hours into one of the most dangerous areas of the Badlands. This drive is so off-road that we pass though 50km of countryside guided by the tyre marks of a single vehicle - tyre marks left there from Phil's trip months earlier.
I am given a safety talk on how to handle myself outside the vehicle (I have a phobia of snakes - and it is highly likely I will see one). I have to stomp loudly and pray the rattlers are deterred by the vibrations from my boots.
We trek for 30 minutes to the suspected print. There is a silence in the air slightly broken by the ominous sounds of the snakes - panic and dehydration start blurring my vision.
The temperature tops 100 degrees but my body temperature seems even higher because I am now wired on adrenalin, which makes what I am about to witness even harder to take in.
At first I think I am staring into a pile of debris covered in branches and twigs but as we start to comb away the confusion something incredible starts to emerge.
Even to an untrained eye, this is unquestionably a "pawprint"; and there's no doubt that if this thing still roamed the Earth, we would live in fear of it.
We have discovered an ancient shrine or listened to a secret message left some 67 million years ago
As I take a step back and witness it in all its prehistoric glory - this huge forbidding footprint - somehow you just know the king of dinosaurs was here.
It is overwhelming - in fact, it is quite an emotional moment.
Suddenly, we feel like we have discovered an ancient shrine or listened to a secret message left some 67 million years ago.
I can not help but touch it; my hand is so small in comparison, it could fit in the print a dozen times over.
I cannot wait to get home to tell this story - the day we walked with T. rex in the Badlands of Montana.
Jacey Normand's report is featured on Inside Out on BBC One, at 1930, on Wednesday, 10 October. Viewers outside the North West region can watch the programme on Sky channel 978 or online at www.bbc.co.uk/insideout