Paleontology in West Virginia

Paleogeographic reconstruction showing the Appalachian Basin area during the Middle Devonian period.

About 500 million years ago during the Cambrian period, West Virginia was almost completely covered by a shallow sea.[2] This sea was inhabited by graptolites, stromatolites, trilobites, and worms.[3] The abundant fossils of the Cambrian Antietam Formation are the oldest evidence of life in the state.[4] West Virginia's Cambrian sea persisted on into the ensuing Ordovician.[2] West Virginia was home to graptolites at that time and they left their remains behind in what would later become dark colored shales.[5] At the same time, mountains were being uplifted in the eastern part of the state.[3] West Virginia's Silurian rocks preserve evidence for the mixing of both marine and non-marine environments.[2] Silurian evaporites left by extremely salty seawater during a dry climate preserved West Virginian eurypterids.[6] Other Silurian life forms of West Virginia included nautiloids with straight shells and an abundance of ostracods.[3] Late in the Devonian the sea quickly withdrew to the west. The Hampshire Formation's continental red beds were deposited during this regression.[2] During the transition from the Silurian to Early Devonian West Virginia was home to corals, whose remains fossilized by silicification.[7] During the Late Devonian the state's seas had begun filling in with sediments eroded from mountains outside of the state.[3]

Reconstruction of Lepidodendron.

However, the state would once more be submerged during the early part of the Carboniferous period.[3] By the Middle Mississippian, the sea had once more expanded its boundaries over the state. In the process it deposited the Greenbrier Formation, which was the last stratigraphic unit of significance to have been laid down in a marine environment. By 310 million years ago, the Mississippian was ending and West Virginia was dry land. West Virginia was swampy during the late Mississippian and its lush flora left behind many plant fossils.[8] During the Mississippian, West Virginia was home to anthracosaur amphibians. One was a long-bodied form about 80 cm long that left behind footprints classified as the ichnospecies Hylopus hamesi. This trackmaker may have been Protergyrinus scheelei, a Mississippian amphibian known from body fossils in West Virginia. The tracks reveal that it was capable of both walking on land and swimming.[9]

Into the Pennsylvanian, the local elevation was low and on brief occasions West Virginia fell below sea level. Huge river systems formed great deltas.[3] Swamps were abundant across West Virginia at the time, and these became its modern coal seams.[2] The dense vegetation of these swamps left behind many plant fossils.[8] The Carboniferous coal swamps of West Virginia were dominated by ground pines of the genus Lepidodendron that could reach more than 100 feet in height. Sigilaria, however, was the largest tree and could be up to six feet in diameter at the base.[10] Other Carboniferous plant fossils in West Virginia include the leaves of seed ferns Alethopteris. Other Pennsylvanian West Virginian seed ferns included Callipteridium, Callipteris, Lescuropteris, and Linopteris.[11] Neuropteris was a contemporary fern-like plant.[10] The true fern Pecopteris also grew in West Virginia during the Pennsylvanian.[12] Amphibians also inhabited in these swamps.[3]

Between 270 and 255 million years ago, during the Permian period, the Appalachian Mountains began to form. West Virginia began losing sediments to erosion rather than accumulating them. No part of West Virginia has been covered in seawater since the Appalachians began rising.[2]

There are no Triassic, Jurassic, or Cretaceous rocks are present in West Virginia, so the entire Mesozoic is missing from the state's rock record.[3] As such, no dinosaur fossils have ever been discovered in West Virginia.[13]

The ensuing Paleogene and Neogene periods of the Cenozoic era is also missing from the state's rock record.[3] During the Ice Age the glaciers never extended sufficiently far south to cross into West Virginia, but during their southernmost extent they nearly approached the northern panhandle.[2] The glaciers dammed the Monongahela River system, forming a lake that extended as far south as Weston.[14] Local wildlife included mammoths, mastodons, and giant ground sloths, who left their remains behind in local caves.[3] One of the most well known fossils from West Virginia is the American cheetah (Miracinonyx inexpectatus)]].[15][16]