How is this possible? If the ground if soft enough for a footprint to form wouldn’t said footprint erode away quickly?
In: Biology
I think the big thing to remember is, 99.99999% of the time they *do* erode away and get lost. It takes pretty special conditions for a fossil to form and that’s why they aren’t all over the place.
If a fossil footprint happens, it might be something like…
(1) animal steps in mud at the bottom of water
(2) sand gets knocked into the water and lands all over the footprint, filling it in and kind of protecting it
(3) fine sediment starts to deposit in the gaps, producing a cast
…and if that sounds improbable, yeah, it is. Again, that’s why we get excited when we find a fossil, because of the gazillions of animal footprints that have happened, almost none had this chain of lucky events happen to preserve it.
Conservation of footprints or the like often happens when the prints are rapidly covered by other material, different from the underlying ground. Another condition that helps is having the prints in slightly wet ground that is only periodically flooded and dried out in between. Tracks left in the drying ground dry out and harden. Then they get covered by some sort of material deposition and thus preserved.
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