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.[1] The earliest fossils from the state are from Esmeralda County, and are Late Proterozoic in age and represent stromatolite reefs of cyanobacteria, 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, archaeocyaths, 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 period, 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. By Cretaceous time all of Nevada was above sea level and was mostly mountainous. In the shallow seaways of the Triassic lived the Ichthyosaurs; typified by the Nevada State Fossil Shonisaurus popularis. While in the Jurassic and Cretaceous periods, dinosaurs and other land animals roamed the state.
After the Mesozoic in the Cenozoic the story of Nevada is one of extension. As the mountains that had been built while dinosaurs were alive began to fall down under their own weight, the modern Basin and Range began. Early Cenozoic Paleogene records are rare, whereas Late Cenozoic Neogene records are plentiful across the state. These Neogene basins record a diverse mammalian biota including camels, horses, giant ground sloths, rhinos, tapirs, and other common Neogene taxa. During this time much of Nevada is also occupied by oak and redwood forests rather than the modern sagebrush steppe.
The Quaternary of Nevada is typified by large pluvial lakes the largest being Lake Lahontan and Lake Bonneville. The deposits of this period show evidence of mammoths, a mastodon from Elko County, sabre-toothed cats, dire wolves, giant short-faced bears, as well as most of the animals still found in the Great Basin and Mojave Deserts today.