If a dinosaur stepped through mud instead of sand, the prints themselves wouldn't survive as fossils; because of its high organic content, mud turns into crumbly coal when compressed beneath other sediment layers. (discovermagazine.com)
During the 20th century, thousands of dams were built on Mississippi River tributaries stopping the flow of fine silt, clay and other sediment from reaching the delta and seafloor to offset erosion. (sciencedaily.com)
Sand and other sediments carried by the water would then have rapidly buried the soft eggs, which was necessary to preserve them, Kellner says. (sciencenews.org)