A quirk of geological circumstance has unearthed a previously undiscovered treasure in the amazing scenery of the Grand Canyon.
In fact, it has revealed the oldest known vertebrate tracks ever found in the historic site.
You see, a cliff collapse has unveiled some ancient footprints that offer an insight into the lives of creatures that roamed the earth way back before humans, and scientists are understandably very excited about it.
The tracks were actually first spotted in 2016 by Allan Krill, a Norwegian geologist on a hiking expedition with some students, but after he sent a photo to a colleague, we've finally found out how significant and old the tracks are.
The paper, published in journal PLOS One on Wednesday (19 August), confirms that these tracks, left by small animals - possibly small reptiles - crossing an ancient sand dune, are the oldest known in the national park.
In a statement, Stephen Rowland - who received the original photos from Krill - said: "These are by far the oldest vertebrate tracks in Grand Canyon, which is known for its abundant fossil tracks.
"They are among the oldest tracks on Earth of shelled-egg-laying animals, such as reptiles, and the earliest evidence of vertebrate animals walking in sand dunes."
The two animals must have crossed the dune within hours or days of one another, the journal explained.
So, what can we tell about these mysterious creatures?
Well, we can tell they walked in 'lateral sequence', meaning that their front and rear legs move together on one side and then the other in order to walk.
This is a trait that can still be found in many animals that walk the earth - one side after the other - to this day.
Rowland continued: "Living species of tetrapods, dogs and cats, for example, routinely use a lateral-sequence gait when they walk slowly.
"The Bright Angel Trail tracks document the use of this gait very early in the history of vertebrate animals. We previously had no information about that."
A tetrapod, in case you're not up to scratch on that term, is any creature that has four limbs.
Admittedly, that doesn't actually narrow things down, because tetrapods could be lizards, amphibians, dinosaurs or even birds.
It's likely that these were 'either basal reptiles or basal synapsids', according to the journal article, but we can't be exactly sure. Synapsids are a broad group of animals that includes mammals and animals more closely related to mammals than reptiles or birds.
Well, we can be fairly sure that these tracks weren't left by birds, but we'll have to wait for further research to be performed and published to find out anything more about these intriguing tracks.
Interesting stuff though, eh?