Paleontology in Montana facts for kids
Paleontology in Montana is all about studying fossils found in the U.S. state of Montana. It also includes the work done by people from Montana who study fossils. Montana's fossil story goes way back to ancient seas where tiny bacteria made stromatolites (layered rock structures). Other sea creatures left their tracks in the mud, which later turned into fossils.
This ancient sea covered Montana for a long time during the early Paleozoic Era. It disappeared for a while during the Silurian and early Devonian periods, leaving a gap in the rock record. When the sea returned, it was home to many creatures like brachiopods (shellfish), conodonts (eel-like animals), crinoids (sea lilies), fish, and trilobites (ancient arthropods). During the Carboniferous Period, Montana had unusual cartilaginous fish (fish with skeletons made of cartilage, like sharks). The sea slowly left again later in the Paleozoic, but came back briefly during the Permian Period.
In the Triassic Period, Montana was again covered by a sea. The only fossils from this time are from the creatures that lived in it. Much of Montana stayed underwater into the Late Jurassic Period. But on land, there were forests of conifers, cycads, ferns, and ginkgoes. This coastal area was home to dinosaurs like the plant-eating Camptosaurus, the long-necked Apatosaurus and Diplodocus, and the meat-eating Allosaurus. During the early Cretaceous Period, the first flowering plants appeared, along with predators like Deinonychus. Later, the Western Interior Seaway, a huge inland sea, covered the state. It was home to giant marine reptiles like mosasaurs and plesiosaurs. On land, duck-billed dinosaurs like Maiasaura formed huge nesting sites. By the end of the Cretaceous Period, Montana was home to famous dinosaurs such as Edmontosaurus, Triceratops, and Tyrannosaurus.
In the early Cenozoic Era, the sea finally left Montana. Fossils from this time include plants, insects, and huge, rhino-like animals called titanotheres. Later, other mammals like arctocyonids (early hoofed mammals), insectivores (insect eaters), multituberculates (rodent-like mammals), pantodonts (early large mammals), primates, and taeniodonts (digging mammals) lived here. As the Cenozoic continued, the climate got colder, leading to the Ice Age. Glaciers moved into the state. In the areas not covered by ice, mammoths, musk oxen, and dire wolves roamed. For thousands of years, local Native Americans found fossils and used them in their stories or for tools. The first scientific fossil collecting in Montana began in the mid-1800s. Other important discoveries include plant and insect fossils from Ruby Valley and the Deinonychus dinosaur, which sparked the "Dinosaur Renaissance." The Cretaceous duck-billed dinosaur Maiasaura peeblesorum is Montana's official state fossil.
Contents
Montana's Ancient Past: A Fossil Story
Montana's fossil record goes all the way back to the Precambrian Period, which was billions of years ago.
Life in Ancient Seas: Precambrian to Carboniferous
During the late Precambrian, western Montana was covered by a warm, shallow sea. This sea was home to stromatolites, which are layered structures made by tiny bacteria. Other sea creatures left tracks in the mud, which later became trace fossils. Life in Montana at this time included early arthropods, blue-green algae, conularians (jellyfish relatives), fungi, and worms. Their fossils are found in what is now Glacier National Park. The worms left behind fossilized burrows and trails.
During the Cambrian Period, most of Montana was still underwater. This sea was home to algae, invertebrates (animals without backbones), and even some of the first known vertebrates (animals with backbones). Later Cambrian trilobites left fossils in places like Nixon Gulch and the Bridger Range. The sea eventually left Montana, and most of the rocks from the Silurian and early Devonian periods were worn away.
However, during the Late Devonian Period, almost all of Montana was covered by the sea again. This sea had brachiopods, conodonts, crinoids, fish, molluscs, and sponges. Seas continued to cover the state into the Carboniferous Period. At that time, Montana was home to many different kinds of cartilaginous fish. Later in the Paleozoic, during the Mississippian Period, brachiopods, bryozoans (tiny colonial animals), and corals left fossils in the Bridger Range. During the Pennsylvanian Period, the sea began to shrink as land in northern Montana rose up. The sea briefly returned to Montana during the Permian Period.
Dinosaurs and Changing Landscapes: Triassic to Cretaceous
During the Early Triassic Period, Montana was about 30 degrees north of the equator. The sea came back twice to cover large parts of Montana during the Triassic. The only fossils from this time are from sea creatures. On land, Montana was hot and dry. The very southwestern corner of Montana had a small part of the shallow sea that covered western North America. South-central Montana, however, was a desert with some streams. Not much is known about other areas because rocks were being worn away instead of being deposited.
During the Jurassic Period, the sea returned to cover Montana. Sediments from higher land in the west slowly filled this sea. By the Late Jurassic Period, most of Montana was underwater, similar to the Triassic sea. Interestingly, at this time, the southwestern part of the state was an island! This sea was home to cephalopods (like squid), crinoids, ichthyosaurs (marine reptiles), and pelecypods (clams). Montana was around 40 degrees latitude. The plants included conifers, cycads, ferns, and ginkgoes. South of Montana's sea was a coastal plain with streams flowing west from higher land in the east. This plain was home to dinosaurs like the plant-eating Camptosaurus, the long-necked Apatosaurus and Diplodocus, and the meat-eating Allosaurus. These fossils are found in what is now called the Morrison Formation.
For 30 million years after the Morrison Formation, rocks in Montana were being worn away. Seawater was still in Montana, extending south from the Arctic Circle. Rivers still flowed into this sea, but the dinosaurs were different. Meat-eaters included Deinonychus and Microvenator. Plant-eaters included Sauropelta (an armored dinosaur) and Tenontosaurus. Around this time, the first flowering plants appeared in Montana.
During the middle Cretaceous Period, Montana was partly covered by the Western Interior Seaway. There were also big volcanic eruptions in Montana during this time. This sea was home to cephalopods, clams, and plesiosaurs. The rocks from this sea are called the Colorado Group. No dinosaur fossils have been found in the Colorado Group in Montana, but some have been found outside the state. Southwestern Montana was dry land, but no dinosaur fossils have been found there yet. About 85 million years ago, the Western Interior Seaway got a bit smaller, leaving western Montana as a coastal plain. Dinosaurs were there, but their fossils are rare. The sea was home to animals like cephalopods, gastropods (snails), mosasaurs, pelecypods, and plesiosaurs.
During the Campanian Stage of the Late Cretaceous Period, the coastal plain next to the Western Interior Seaway had rivers and a few lakes. These waters left behind the rocks that became the Two Medicine Formation. Nearby volcanoes were erupting, leaving behind ash that turned into bentonite clay. The climate was semiarid (partly dry). The plants on the coastal plain included conifer forests, deciduous trees (trees that lose their leaves), and ferns. Many different dinosaurs lived in Montana at this time. Duck-billed hadrosaurs were common, like Maiasaura. Montana has a very good fossil record of ceratopsid dinosaurs (horned dinosaurs). An example is Einiosaurus. The meat-eating theropods Daspletosaurus and Troodon were also present. Both Maiasaura and Troodon are known to have had nesting sites in the area. Late Cretaceous dinosaur footprints are surprisingly rare in Montana compared to other western states. This might be because the ancient environments weren't good for preserving tracks, or scientists just haven't found the right places yet.
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Early in the Maastrichtian Stage, the Western Interior Seaway grew a bit. It was home to cephalopods, clams, crustaceans, fish, gastropods, mosasaurs, and plesiosaurs. Later in the Maastrichtian, volcanoes were still active in the Elkhorn area, and the Western Interior Seaway began to shrink. This shrinking eventually connected the two halves of North America. As the seaway left, the area closest to the Rocky Mountains became a growing desert. Eastern Montana, however, was hot and humid, as the coastal plain also grew because the sea was leaving. By the late Maastrichtian, large rivers flowed across eastern Montana, leaving behind the rocks that would become the Hell Creek Formation. At this time, Montana was home to some of the most famous dinosaurs, including Edmontosaurus, Pachycephalosaurus, Triceratops, and Tyrannosaurus.
Mammals and the Ice Age: Cenozoic Era
During the early Cenozoic Era, the sea finally left Montana for good. Huge movements in the Earth's crust helped form the local mountains and raised much of the state's land. Rainfall levels went up and down. Montana was home to creatures like early dog-like animals and titanotheres. The rocks from the Tertiary Period in southwestern Montana are some of the best places to find plant and insect fossils in North America. More than 200 species of plants, insects, and fish are known from these rocks. The plants included water lilies and lotuses. During the Tertiary, Montana had swamps that later formed coal.
The invertebrate fossils included ants, bees, beetles, earwigs, caddisflies, crane flies, damselflies, lantern flies, mayflies, grasshoppers, leafhoppers, mosquitoes, snails, and wasps. Vertebrate fossils included feathers and, sometimes, a bird. Among the plants from the Oligocene Epoch in Montana were ailanthus (tree of heaven), ash, beech, cattails, cedar, cinquefoil, dogwood, elm, ferns, milfoil fernbush, gooseberry, climbing grapes, grasses, greenbriers, horsetails, ironwood, katsura tree, liverwort, mountain mahogany, maple, false mermaid, mosses, oak, pennycress, pondweed, dawn redwood, roses, sedges, smoke tree, snowberry, spiraea, false strawberry, and vetches. Similar plants are found in Colorado and Oregon. Montana's Miocene plants and mollusks left fossils at Bear Butte. The Miocene mammals found there included arctocyonids, insectivores, multituberculates, pantodonts, primates, and taeniodonts. During the Miocene, Montana also had camels and horses. Later in the Cenozoic, Montana became colder and wetter. Glaciers carved out the land. At this time, mammoths, musk oxen, and dire wolves lived in the parts of the state not covered by ice.
Discovering Montana's Past: Scientific Research
Early Fossil Finds: 1855 to Early 1900s
In 1855, Ferdinand Vandeveer Hayden, a geologist with the United States Geological Survey, was exploring what is now central Montana, near the Judith River. He found fossils of bones, shells, and teeth. When he returned, he gave the fossils to Joseph Leidy in Philadelphia. Leidy realized these teeth were different from any known animal, but they clearly belonged to a dinosaur because they were similar to dinosaur fossils found in England. Leidy made the first scientific identification of dinosaur fossils from Montana. Since these remains were new, Leidy named three new types of dinosaurs: Deinodon horridus, Trachodon mirabilis, and Troodon formosus.
In 1901, Dr. Earl Douglass discovered fossil plants, mollusks, and vertebrae (backbones) at Bear Butte, northwest of Melville. In 1933, another fossil site opened in the same area. By 1937, 57 different fossil sites were known from these beds, and 25 were very important. Among the finds were arctocyonids, insectivores, multituberculates, pantodonts, primates, and taeniodonts.
Important Discoveries: Mid-1900s to Present
Montana's Tertiary Period fossils in the Ruby Valley basin were first studied in 1947 by Dr. Herman F. Becker for the New York Botanical Garden. These fossils from southwestern Montana are some of the best sources of plant and insect fossils in North America. In 1959, Becker's work in Ruby Valley uncovered about 5,000 specimens of over 200 species of plants, insects, and fish. Invertebrate finds included ants, bees, beetles, earwigs, caddisflies, crane flies, damselflies, lantern flies, mayflies, grasshoppers, leafhoppers, mosquitoes, snails, and wasps. Vertebrate remains included feathers and, sometimes, a bird. In 1961, a new group of plants was found nearby in a badger burrow. This group is called the Badger Flora and included water lilies and lotuses.
In 1964, John Ostrom led an expedition, which included his student Robert T. Bakker, to south-central Montana. They explored rocks from the Cloverly Formation, which date back to the Early Cretaceous Period. They found the first documented remains of a small meat-eating dinosaur that would be named Deinonychus antirrhopus. This discovery helped start the "Dinosaur Renaissance." It showed important similarities between dinosaurs and birds, helping scientists realize that dinosaurs were not just "overgrown lizards."
In 1978, paleontologist Bill Clemens told Jack Horner and Bob Makela about some unidentified dinosaur fossils in Bynum. Horner visited the town and recognized the bones as belonging to a duck-billed dinosaur. While there, a local rock shop owner, Marion Brandvold, showed him some tiny bones. Horner identified them as baby duck-bill bones. Horner knew this was an important find and convinced Brandvold to donate her fossils to a museum. She agreed and gave them to Princeton University. Horner's team then explored the area where Brandvold found the baby hadrosaur fossils. Their hard work led to the discovery of the first scientifically documented dinosaur eggs in the Western Hemisphere and a new type of duck-billed dinosaur, Maiasaura peeblesorum.
People Who Studied Montana's Fossils
- Gloria Jean Siebrecht was born in Kalispell in 1940.
- John R. Horner was born in Shelby on June 15, 1946.
Places to See Fossils: Natural History Museums
