It was Professor Phil Manning who discovered the first known Tyrannosaur footprint in the Hell Creek formation in Montana.
He’d seen it on the last day of an expedition in 2006 but did not have the time to investigate further, so he returned the following year and began to search for it all over again.
It is rather unremarkable to look at and unless you knew what you were looking at you wouldn’t notice it.
Rather thinner than one would expect a foot to be, the toes only just joined to the main foot and it is raised in profile rather than indented.
And it is much darker than the rock around it.
It measures around 29 inches long and similarly wide and was formed when a T-Rex walked in the clay of a flood plain, compressing it enough that it became tougher than the rock surrounding it and so it survived, just, when the rock around it eroded.
As well as the footprint itself being the right size and shape for a T-Rex, the other compelling evidence that this is genuinely from a T-Rex is that it was discovered right where it is known T-Rex died, and therefore lived.
One that was claimed to have been found in Mexico was disputed and dismissed as there was no sign anywhere near it that T-Rex was ever there.
Now one has been found, others will come to light but considering the timescale it is astounding that even one survives.