Paleontology in Minnesota

The geologic record of Minnesota spans from Precambrian to recent with the exceptions of major gaps including the Silurian period, the interval from the Middle to Upper Devonian to the Cretaceous, and the Cenozoic.

[1] During the Precambrian, Minnesota was covered by an ocean where local bacteria ended up forming banded iron formations and stromatolites.

During the early part of the Paleozoic era southern Minnesota was covered by a shallow tropical sea that would come to be home to creatures like brachiopods, bryozoans, massive cephalopods, corals, crinoids, graptolites, and trilobites.

The Paleogene and Neogene periods of the ensuing Cenozoic era are also missing from the local rock record, but during the Ice Age evidence points to glacial activity in the state.

[2] Late Cambrian life in Minnesota included brachiopods, cystoids, graptolites, pteropods, a variety of trilobites, and worms.

Worms living in Late Cambrian Minnesota left behind trace fossils of the trails they made through the sediment.

[1] Ordovician Minnesota still hosted this sea, although there may have been times during this period when it expanded to submerge the entire state.

[3] Other animals that inhabited Minnesota during the Ordovician included brachiopods, bryozoans, corals, crinoids, graptolites, and trilobites.

During the ensuing Devonian period, the sea returned to southern Minnesota and local sediment deposition resumed.

[2] The gap in the fossil record that began in the late Paleozoic spans the entire Triassic period of the ensuing Mesozoic era.

[11][12] Scant dinosaur fossils have been discovered in Minnesota[13] such as the claw of a dromaeosaur,[14] and hadrosaur bones preserved in the Dakota Formation.

[20] Among the Pleistocene fauna of Minnesota were badgers, beavers, bison, elk, woolly mammoths, mastodons, musk oxen, rabbits, reindeer, rodents, and skunks.

[11] Bison fossils are very common and were even preserved in sizable bonebeds in places like at Riverton's Sagamore Iron Mine and another in Itasca State Park.

[11] The Dakota Sioux of Minnesota believed in a water monster called Unktehi, which was thought to resemble a giant buffalo.

[22] The Dakota Sioux of Minnesota also believed in the Wakinyan, gigantic thunderbirds thought to be the mortal enemy of Unktehi and the water monsters.