No slide show is available for the Ordovician in Montana.
Paleontology and geology
After an early episode of erosion, shallow seas flooded the state. Tectonic activity created a basin to the east, and the sea encroached from the southwest. These warm marine waters supported a diversity of algae, crinoids, bryozoans, brachiopods, and corals. Remnants of some of the earliest vertebrates also occur.
