At https://scitechdaily.com/we-were-freaking-out-scientists-explore-dinosaur-coliseum/ … scientists discovered and documented a single dinosaur track site in Alaska, and were blown away. The location is known as the coliseum. It comprises an assemblage of rock layers, each preserving a wealth of dinosaur footprints. It is not one rock layer with tracks, as one might find elsewhere. It is a sequence through time, we are told. Layer on top of layer. On the other hand the layers may have been laid down quickly, compressing the ones below and rapidly preserving the footprint. Otherwise we would have to imagine footprints being preserved for long periods of time, prior to burial by sediments. Is that even possible?
The coliseum is a cliff formation. A dinosaur trackway can be seen at the base of the cliff. It dates to the Late Cretaceous period – leading up to the dinosaur killing asteroid. Or the rapid layers of mud were laid down as part of that upheaval, and preserved. The cliff was laid down as sediments on flat ground, we are told, near what was possibly a watering hole. The latter idea seems to be speculation to account for so many dinosaurs in a single location. As the earth buckled to form the Alaska Range mountain chain, at a much later date, the flat ground folded and tilted vertically, exposing the cliff formation with the tracks. The tracks, we are also informed, were formed in mud that overwhelmed the tracks, or filled in the tracks and then hardened. So, there was a lot of mud slurping around.
In addition, the team found fossilised plants, pollen grains, and fossilised shellfish and invertebrae etc. The environment was, it seems, the flood plain of a large river system, with pools and lakes. There were coniferous and deciduous trees as well as flowers and horsetails. It would have been much warmer in Alaska at that time. See https://doi.org/10.1080/08912963.2023.2221267 …