Most fossils are found in marine sediments, as water preserves animals the best by quickly cutting off the oxygen supply to the animal which allows for better preservation. Marine sediments can be identified easily and there are several different kinds. Very quiet water from a lagoon or lake is typified by very fine sediments that usually take a long time to settle in a quiet lake. Rocks from this kind of environment often have fossils that are some of the best preserved, lying at the bottom of the lake, undisturbed. A great example of these types of sediments are in shales, and the Solnhofen limestone in Germany. Black shales are typical of anoxia (lack of oxygen) from quiet oceans or lakes. One example of that is the Burgess Shale, in Yoho National Park in BC.
|Marrella a typical Burgess Shale fossil (image from Wikimedia Commons user PurpleHz)|
|An example of an ophiuroid (also known as a brittle star) from the Solnhofen of Germany (image from Wikimedia Commons user UlrichStill)|
|Photo from an Edmontosaurus bonebed showing jumbled nature of dinosaur bones in bone beds. Photo copyright of Liz Martin|
There are lots of other sedimentological and geological details that can be useful to palaeontologists to help understand the environment or even the cause of death for the animals.