Paleontology in Minnesota facts for kids
Paleontology in Minnesota is all about studying ancient life in the state of Minnesota. Scientists look for fossils here to learn about plants and animals that lived long, long ago. Minnesota's geologic record shows us what happened from the very old Precambrian time right up to today. However, there are some big gaps where no rocks or fossils from certain periods have been found.
Millions of years ago, during the Precambrian time, Minnesota was covered by an ocean. Tiny bacteria in this ocean created special layered rocks called banded iron formations and stromatolites. Later, in the early Paleozoic era, southern Minnesota was under a warm, shallow tropical sea. This sea was home to many amazing creatures like brachiopods (shellfish), bryozoans (moss animals), huge cephalopods (like giant squids), corals, crinoids (sea lilies), graptolites (tiny colonial animals), and trilobites (ancient arthropods).
The sea left Minnesota during the Silurian period, but it came back during the Devonian period. After that, much of the rest of the Paleozoic era is missing from Minnesota's rock record. The Triassic period is also missing, and while there are Jurassic rocks, they don't have many fossils. Another sea covered Minnesota during the Cretaceous period. This sea had creatures like ammonites (shelled cephalopods) and sawfish. On land, duck-billed dinosaurs roamed.
After the time of the dinosaurs, the Cenozoic era also has big gaps in Minnesota's rock record. But during the recent Ice Age (the Quaternary glaciation), glaciers covered parts of the state. Animals like woolly mammoths, mastodons, and musk oxen lived here. Long ago, Native Americans in the area found these ancient bones. They believed they were from a water monster called Unktehi. They also told stories about "thunder birds," which might have been inspired by fossils of large Ice Age birds. By the early 1800s, scientists started studying Minnesota's fossils, including ancient plants from the Cretaceous period.
Ancient Life in Minnesota
Life in the Precambrian Ocean
During the Precambrian time, Minnesota was covered by a vast ocean. Tiny living things, like bacteria, were very important then. These bacteria helped create special layered rocks called banded iron formations and stromatolites. These rocks are some of the oldest signs of life in Minnesota.
Paleozoic Seas and Creatures
Early Life in Tropical Seas
In the early Paleozoic era, Minnesota was located near the equator. This meant it had a tropical climate. The southern part of the state was covered by a shallow sea. During the Late Cambrian period, this sea was full of life. We find fossils of brachiopods, cystoids (ancient sea creatures), graptolites, pteropods (sea snails), many types of trilobites, and worms. Some worms left behind trace fossils, which are the trails they made in the soft mud.
Ordovician Ocean Life
The sea stayed in Minnesota during the Ordovician period. At times, it might have covered the entire state! The most common fossils from the Early Ordovician are ancient microbial mats and stromatolites. Other creatures included cephalopods, gastropods (snails), and trilobites. Some of the cephalopods in Minnesota during this time were huge, growing up to 5 to 15 feet (1.5 to 4.5 meters) long! Fossils of these giant cephalopods have been found in the Cherokee Park area.
Other animals living in Minnesota during the Ordovician included brachiopods, bryozoans, corals, crinoids, graptolites, and trilobites. Even ancient marine plants left their fossils in the state. Later in the Ordovician, brachiopods, bryozoans, crinoids, and molluscs (like clams and snails) were very common.
Devonian Sea Returns
The sea left Minnesota during the Silurian period. This means no new rocks were formed, and older ones were worn away. So, we don't have any fossils from that time. But during the Devonian period, the sea returned to southern Minnesota. This brought new life, including brachiopods, cephalopods, corals, and trilobites. In the Late Devonian, brachiopods and corals were common. Their fossils have been found in Fillmore, Freeborn, and Mower Counties. We also find fragments of fish fossils from this time, but no complete skeletons. After the Devonian, the Paleozoic fossil record in Minnesota ends, as there are no rocks from the Carboniferous or Permian periods.
Mesozoic Era: Dinosaurs and Ancient Seas
There's a big gap in the fossil record after the Paleozoic, covering the entire Triassic period. However, during the Jurassic period, a sea once again came into the state. Sadly, no fossils have been found from this sea.
Cretaceous Seas and Land Life
Minnesota was home to the edge of another sea during the Cretaceous period. This sea was filled with ammonites, clams, and oysters. Ammonite and oyster fossils have been found in the Coleraine area. Other creatures like gastropods and pelecypods (bivalves) left many fossils in the Mesabi Range. Fish teeth and bones have been found in Big Stone County. Even sawfish lived in Minnesota during the Cretaceous!
On land, the climate was hot, and plants thrived. Minnesota's Cretaceous plant fossils show more than 200 different kinds of plants! These included cycads, Equisetum (horsetails), evergreens, ferns, laurels, pomegranates, poplars, tulip trees, giant redwoods, and willows.
We don't find many dinosaur fossils in Minnesota, but some have been discovered. These include the claw of a dromaeosaur (a type of raptor dinosaur) and hadrosaur (duck-billed dinosaur) bones in the Dakota Formation. Many of Minnesota's dinosaur fossils are just bones and teeth that drifted into the ancient Western Interior Seaway after the dinosaurs died.
Ice Age Animals
After the time of the dinosaurs, there's another big gap in Minnesota's rock record, covering most of the Cenozoic era. But during the Pleistocene epoch (the last Ice Age), glaciers covered parts of Minnesota. We find fossils of plants from this time, like logs, branches, leaves, and mosses.
Many amazing animals lived in Minnesota during the Ice Age. These included badgers, beavers, bison, elk, woolly mammoths, mastodons, musk oxen, rabbits, reindeer, rodents, and skunks. Bison fossils are very common and have even been found in large groups called bonebeds at places like the Sagamore Iron Mine near Riverton and in Itasca State Park. Elk remains are also quite common.
Paleontology Research in Minnesota
Early Scientific Discoveries
In the late 1800s, scientists like Charles Schuchert and Leo Lesquereux began studying Minnesota's fossils. Schuchert explored rock layers in southeastern Minnesota, in Goodhue County, Olmsted County, and Fillmore County.
Leo Lesquereux was famous for finding and describing over 200 different kinds of Cretaceous plants in Minnesota. His discoveries included many types of conifers, cycads, and dicotyledons (flowering plants). He also found Equisetum, ferns, and monocotyledons. Lesquereux was amazed by how quickly dicots seemed to appear in the fossil record without clear transitional forms.
Natural History Museums
If you want to see some of Minnesota's amazing fossils and learn more about its ancient past, you can visit these museums:
