Indiana's fossil record stretches all the way back to the
Precambrian.
Microbe fossils of this age are known from the state. Later, during the
Cambrian period, Indiana was located in equatorial latitudes. Indiana was also covered by a warm shallow sea. This sea was home to
brachiopods,
trilobites, and
sponges. In the ensuing
Ordovician period Indiana was still submerged by the sea. The state was home to brachiopods,
bryozoans,
cephalopods,
crinoids,
gastropods,
pelecypods, and trilobites. The Paleozoic sea covering Indiana remained in place during the
Silurian Period. At the time northern and southwestern Indiana were covered in
reefs composed of animals like corals and
stromatoperoids. These reefs were situated at the edges of areas with greater depths of water both within and outside the state. The Terre Haute Reef Bank is located in the southwestern part of the state and contains more than 60 reefs. Some of these ancient reefs later proved economically significant to humans because the overlying rock would sometimes bear
petroleum deposits or could be employed by utility companies as
natural gas storage sites. The Fort Wayne Bank is located near the surface of the northern region of the state. More than 20 of the reefs have been mined for aggregate, which is reputedly of high quality. Other Indianan life during the Silurian included brachiopods, bryozoans, crinoids,
eurypterids, gastropods, pelecypods, and trilobites. ''. The same sea that had covered Indiana since the Cambrian was still home to a variety of ancient life forms during the
Devonian. Examples include brachiopods, bryozoans, corals, cephalopods, pelecypods, and trilobites. During the
Carboniferous the state was home to
river systems that formed vast
deltas. The plants growing across these deltas would leave behind
coal deposits. Wildlife of the
Mississippian epoch included
arthropods, brachiopod, bryozoans, cephalopods, corals, crinoids,
foraminifera,
fishes,
molluscs, and trilobites. Pennsylvanian life of included
amphibians,
Calamites,
Cordaites,
lycopods,
seed ferns, and
true ferns. There are no fossils in Indiana from the interval spanning across the
Permian period and the entire
Mesozoic era. At that time local sediments were being eroded away rather than deposited. As such, there are no rocks from this time in which fossils could have been preserved. Although
dinosaurs probably lived in Indiana during the Mesozoic, the absence of rocks from the time means that there are no dinosaur fossils in the state. Little is known about the
Tertiary history of Indiana because there are so few rocks of this age in the state. Nevertheless, local vertebrates, invertebrates, and plants have been preserved in
sinkholes. Later, during the ensuing
Quaternary period, Indiana was worked over by
glaciers. Indiana was inhabited by creatures like the
birds,
camels, fishes,
peccaries, the
short-faced bear,
rodents,
snakes, and
turtles. In nearly recent times the biota of Indiana included
dire wolves, gastropods,
mammoths,
mastodons, pelecypods,
plants (which left both body and pollen fossils), and
saber-toothed cats. ==History==