page_title: Paleontology in Nevada
section_title: Prehistory
hierarchical_section_title: Paleontology in Nevada / Prehistory
caption_attribution_description: English: Shonisaurus popularis English: Shonisaurus popularis
context_page_description: Paleontology in Nevada refers to paleontological research occurring within or conducted by people from the U.S. state of Nevada. Nevada has a rich fossil record of plants and animal life spanning the past 650 million years of time. The earliest fossils from the state are from Esmeralda County, and are Late Proterozoic in age and represent reefs of photosynthesizing blue-green algae, amongst these reefs were some of the oldest known shells in the fossil record, the Cloudina-fauna. Much of the Proterozoic and Paleozoic fossil story of Nevada is that of a warm, shallow, tropical sea, with a few exceptions towards the Late Paleozoic. As such many fossils across the state are those of marine animals, such as trilobites, brachiopods, bryozoans, honeycomb corals, and horn corals.
  After the Paleozoic, tectonic activity on the western margin of North America increased. This increase in tectonism forced portions of Nevada formerly below sea level higher. In the Triassic northern and central Nevada were shallow seaways between mountainous island arcs, while in southern Nevada the same story as Petrified Forest National Park played out in the swamps at the edge of the continent.
context_section_description: During the Late Precambrian eastern and southern Nevada was being gradually covered by a shallow sea. Blue-green bacteria from this time period were preserved in those areas of the state. More than 500 kinds of Paleozoic invertebrates are known to have inhabited Nevada during the Cambrian, Devonian, and Carboniferous periods of the Paleozoic era. Most of the invertebrates known from this time were freshwater mollusks. The sea continued to expand into the state through the Devonian. During that period northwestern Nevada's sea began to get deeper, gradually becoming an ocean basin. These deeper water areas of Devonian Nevada were home to drifting animals like graptolites. The shallower water regions were home to reefs. Near the end of the Devonian an interval of mountain building called the Antler Orogeny began. The Antler Orogeny continued into the Early Carboniferous. Dropping sea levels exposed regions of Nevada as dry land. Environments of eastern Nevada included lagoons and beaches. Local plant life were preserved in rocks formed by these deposits. Northern and northeastern Nevada were still home to reef habitats. Northwestern Nevada was still a deep ocean. Its abundant plankton left behind many fossils.
  Nevada's sea level continued to drop during the Triassic period. However, the western part of the state was still relatively deep. It was home to a rich ammonite and ichthyosaur fauna. During the Triassic, many invertebrates lived and died in the area now occupied by the Shoshone Mountains. Their fossils are scientifically significant as many are now used as index fossils or were completely unknown to science before their discovery here. By the Jurassic, the only deep marine habitats of Nevada were in the northwestern part of the state. Central Nevada was only under shallow water and the eastern and southern parts of the state were characterized by other types of environment. During the Cretaceous, a volcanic island chain formed in far western Nevada. Contemporary plant fossils from Nevada include "twigs" of petrified wood preserved in Eureka County. These may be the remnants of ancient Sequoia trees. Local dinosaurs included armored dinosaurs, possible duck-billed dinosaurs and relatives of the horned dinosaurs.
  During the Cenozoic geologic upheaval created the state's Basin and Range physiographic province. Woodlands harboring trees like oak, redwood, and willow formed in Nevada. Local wildlife included creatures like horses, mammoths, and rhinos. Volcanic eruptions regularly shook the state during the Cenozoic. Some of Nevada's Miocene life was preserved in the sediments composing what are now known as the Truckie Beds of the Kawich Mountains northeast of modern Las Vegas. Local bodies of fresh water were inhabited by mollusks at the time. On land Nevada was home to a variety of mammals including both mastodons and rhinoceroses. As the Cenozoic continued, Nevada's Sierra Nevada Mountains were raised. Volcanic activity was still ongoing. Local wildlife included camels, horses, mammoths, and giant ground sloths. Nevada's trace fossil record from the Pleistocene is very rich. One site preserved the footprints of a diverse menagerie of creatures including birds, giant sloths, horses, lions, mastodons, and wolves.
caption: Shonisaurus popularis.
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