U.S. states, districts, and territories have representative symbols that are recognized by their state legislatures, territorial legislatures, or tradition. Some, such as flags, seals, and birds have been created or chosen by all U.S. polities, while others, such as state crustaceans, state mushrooms, and state toys have been chosen by only a few.
The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone, and limestone and is light gray, greenish gray, or red. Most of the fossils occur in the green siltstone beds and lower sandstones, relics of the rivers and floodplains of the Jurassic period.
