The location of the state of Illinois Paleontology in Illinois refers to

paleontological Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (geology), epoch (roughly 11,700 years before present). It includes t ...

research occurring within or conducted by people from the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sover ...

Illinois Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolita ...

. Scientists have found that Illinois was covered by a

sea The sea, connected as the world ocean or simply the ocean, is the body of salty water that covers approximately 71% of the Earth's surface. The word sea is also used to denote second-order sections of the sea, such as the Mediterranean Sea, ...

during the

Paleozoic Era The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...

. Over time this sea was inhabited by animals including

brachiopods Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, whi ...

clam Clam is a common name for several kinds of bivalve molluscs. The word is often applied only to those that are edible and live as infauna, spending most of their lives halfway buried in the sand of the seafloor or riverbeds. Clams have two she ...

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and sec ...

crinoid Crinoids are marine animals that make up the class Crinoidea. Crinoids that are attached to the sea bottom by a stalk in their adult form are commonly called sea lilies, while the unstalked forms are called feather stars or comatulids, which are ...

sea snail Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...

sponge Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through t ...

s, and

trilobite Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the At ...

s. Fossils are common from the

Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start ...

through the Pennsylvanian. Illinois has a reputation for rocks bearing large numbers of trilobite fossils, often of very high preservational quality. There is a gap in Illinois' geologic record from the

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...

to the

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

. During the

Ice Age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gree ...

, Illinois was subject to

glacial A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betw ...

activity. At the time the state was home to creatures like

giant beavers ''Castoroides'' (Latin: "beaver" (castor), "like" (oides)), or giant beaver, is an extinct genus of enormous, bear-sized beavers that lived in North America during the Pleistocene. Two species are currently recognized, ''C. dilophidus'' in the ...

mammoths A mammoth is any species of the extinct elephantid genus ''Mammuthus'', one of the many genera that make up the order of trunked mammals called proboscideans. The various species of mammoth were commonly equipped with long, curved tusks and, ...

mastodons A mastodon ( 'breast' + 'tooth') is any proboscidean belonging to the extinct genus ''Mammut'' (family Mammutidae). Mastodons inhabited North and Central America during the late Miocene or late Pliocene up to their extinction at the end of th ...

, and

stag moose ''Cervalces scotti'', the elk moose or stag-moose, is an extinct species of large deer that lived in North America during the Late Pleistocene epoch. It had palmate antlers that were more complex than those of a moose and a muzzle more closely re ...

s. Paleontology has a long history in the State of Illinois, stretching at least as far back as the 1850s, when the first

Mazon Creek The Mazon Creek fossil beds are a conservation ' found near Morris, in Grundy County, Illinois. The fossils are preserved in ironstone concretions, formed approximately in the mid- Pennsylvanian epoch of the Carboniferous period. These concreti ...

fossils were being found. Early in the ensuing 20th century a

Silurian The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozo ...

age fossil

reef A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes— deposition of sand, wave erosion planing down rock out ...

system was discovered in the state. In the 1950s

Francis Tully Francis may refer to: People *Pope Francis, the head of the Catholic Church and sovereign of the Vatican City State and Bishop of Rome *Francis (given name), including a list of people and fictional characters *Francis (surname) Places *Rural Mu ...

discovered the "monster" that would later be named in his honor. The Pennsylvanian species ''

Tullimonstrum gregarium ''Tullimonstrum'', colloquially known as the Tully monster or sometimes Tully's monster, is an extinct genus of soft-bodied bilaterian animal that lived in shallow tropical coastal waters of muddy estuaries during the Pennsylvanian geological ...

'' ("Tully Monster") is the Illinois

state fossil Most American states have made a state fossil designation, in many cases during the 1980s. It is common to designate one species in which fossilization has occurred, rather than a single specimen, or a category of fossils not limited to a single ...

. It is one of the few officially designated state fossils that is endemic to the state it represents.

Prehistory

No Precambrian fossils are known from Illinois. As such, the state's fossil record does not begin until the Paleozoic. Illinois was covered by a

during the

Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...

. Over time this sea would be inhabited by animals like

brachiopod Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, w ...

snail A snail is, in loose terms, a shelled gastropod. The name is most often applied to land snails, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class Gastro ...

s. 500 million years ago, during the

Cambrian The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...

, the seas of Illinois resembled those of the modern

Bahamas The Bahamas (), officially the Commonwealth of The Bahamas, is an island country within the Lucayan Archipelago of the West Indies in the Atlantic Ocean, North Atlantic. It takes up 97% of the Lucayan Archipelago's land area and is home to ...

. At the time, Illinois was located near the

equator The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can als ...

. Illinois was home to

trilobites Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the At ...

. Cambrian trilobites left their remains in the state's north-central region. In other areas of Illinois Cambrian trilobite fossils have only been found in core samples drilled from deeply buried rocks.

Ordovician

During the

, Illinois was still located near the equator and still covered by a shallow

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

sea.

Graptolite Graptolites are a group of colonial animals, members of the subclass Graptolithina within the class Pterobranchia. These filter-feeding Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and ...

s reached their peak abundance in the state's history during this time. They left remains behind in the northern part of the state.

Cephalopod A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...

s were diverse during the Ordovician with some having straight shells and others being coiled. They left behind remains in northern and western Illinois.

Gastropods The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. Ther ...

were common. "Sunflower coral"

sponges Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through ...

were also common in north-central Illinois. Trilobites were still present and Ordovician rocks are a better source of trilobite fossils than the state's Cambrian deposits. However, this is due to the Ordovician rocks being more accessible to collectors than the older ones. Ordovician trilobites from Illinois included ''

Isotelus ''Isotelus'' is a genus of asaphid trilobites from the middle and upper Ordovician period, fairly common in the Northeastern United States, northwest Manitoba, southwestern Quebec and southeastern Ontario. One species, ''Isotelus rex,'' is curre ...

'' and ''

Ceraurus ''Ceraurus'' is a genus of cheirurid trilobite of the middle and, much more rarely, the upper Ordovician. They are commonly found in strata of the lower Great Lakes region. These trilobites have eleven thoracic segments, a very small pygidium a ...

''. Ordovician trilobites left behind remains in northern and southwestern Illinois. Marine worms flourished in the bottom sediment of the sea that covered Illinois. Their presence is attested to be fossils of their jaws. After the Ordovician trilobite abundance and diversity declined significantly.

Silurian

Tropical marine conditions continued to persist into the Silurian. Trilobites were still present and like the Ordovician Silurian rocks are a better source of trilobite fossils than the state's Cambrian deposits. Also like the Ordovician, the superiority of Silurian rocks as a source of trilobites is due to the Silurian rocks being more accessible to collectors than the older ones. Silurian trilobites from Illinois include ''

Dalmanites ''Dalmanites'' is a genus of trilobite in the order Phacopida. They lived from the Late Ordovician to Middle Devonian. The trilobites of this genus have slightly convex exoskeletons with an average length of . The cephalon is semicircular or pa ...

'' and ''

Calymene ''Calymene'' Brongniart, 1822, is a genus of trilobites in the order Phacopida, suborder Calymenina, that are found throughout North America, North Africa, and Europe in primarily Silurian outcrops. ''Calymene'' is closely related to ''Flexicaly ...

''. Silurian trilobites left behind remains in northern and southwestern Illinois. '' Hindia'' sponges lived in the Silurian near

Chicago (''City in a Garden''); I Will , image_map = , map_caption = Interactive Map of Chicago , coordinates = , coordinates_footnotes = , subdivision_type = Country , subdivision_name ...

. Another Silurian resident of the Chicago region were

cystoids Cystoidea is a class of extinct crinozoan echinoderms, termed cystoids, that lived attached to the sea floor by stalks. They existed during the Paleozoic Era, in the Middle Ordovician and Silurian Periods, until their extinction in the Devonian ...

. Most of the state's cystoid fossils are preserved in deposits that formed in that place and time Jaws left by marine worms are even more common from the Silurian of northeastern Illinois than they were back in the Ordovician. Illinoisan trilobites diversity and abundance suffered further losses after the end of the Silurian Period.

Devonian

During the Devonian Illinois was still covered by the sea and had not drifted far north from the equator. Trilobites were still present. Devonian trilobites from Illinois included ''

Phacops ''Phacops'' is a genus of trilobites in the order Phacopida, family Phacopidae, that lived in Europe, northwestern Africa, North and South America and China from the Late Ordovician until the very end of the Devonian, with a broader time range d ...

'' and '' Odontocephalus''.

Mississippian

Illinois was still under seawater during the early Carboniferous.

Bryozoans Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about long, they have a special feeding structure called a l ...

were very common all throughout Illinois during the Mississippian epoch. Brachiopods were also very common in the Mississippian of the

Mississippi Mississippi () is a state in the Southeastern region of the United States, bordered to the north by Tennessee; to the east by Alabama; to the south by the Gulf of Mexico; to the southwest by Louisiana; and to the northwest by Arkansas. Miss ...

and

Ohio River The Ohio River is a long river in the United States. It is located at the boundary of the Midwestern and Southern United States, flowing southwesterly from western Pennsylvania to its mouth on the Mississippi River at the southern tip of Illino ...

areas. Mississippian trilobites from Illinois included '' Brachmetopus''.

Pennsylvanian

Illinois was still located near the equator during the Pennsylvanian. Western and central Illinois was covered in swamps bordering the remnants of the shallow sea that once covered the state.

Fusulinids The Fusulinida is an extinct order within the Foraminifera in which the tests are traditionally considered to have been composed of microgranular calcite. Like all forams, they were single-celled organisms. In advanced forms the test wall was dif ...

are common in Pennsylvanian rocks. Shelled cephalopods were diverse during the Pennsylvanian with some having straight shells and others being coiled. Other inhabitants included the

Tully monster ''Tullimonstrum'', colloquially known as the Tully monster or sometimes Tully's monster, is an extinct genus of soft-bodied bilaterian animal that lived in shallow tropical coastal waters of muddy estuaries during the Pennsylvanian geologica ...

, as well as animals recognizably related to modern life like

shrimp Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are refer ...

jelly fish Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbrella- ...

sharks Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorp ...

and

squid True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting t ...

Coelacanths The coelacanths ( ) are fish belonging to the order Actinistia that includes two extant species in the genus ''Latimeria'': the West Indian Ocean coelacanth (''Latimeria chalumnae''), primarily found near the Comoro Islands off the east coast ...

were among the state's Pennsylvanian aquatic vertebrates. Gastropods were common. Clams were common in central Illinois during the Pennsylvanian. Illinoisan

horseshoe crab Horseshoe crabs are marine and brackish water arthropods of the family Limulidae and the only living members of the order Xiphosura. Despite their name, they are not true crabs or crustaceans: they are chelicerates, most closely related to arachn ...

fossils are only known from the Pennsylvanian of the

area. Trilobites were still present in Illinois and included ''

Ameura ''Ameura'' is an extinct genus of trilobite belonging to the family Proetidae. Fossils from the genus have been found in late Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The nam ...

'' and ''

Ditomopyge ''Ditomopyge'' is an extinct genus of trilobite belonging to the family Proetidae. It was extant during the Carboniferous and Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of t ...

''. 325 million years ago Illinois was covered in heavily forested

deltaic A river delta is a landform shaped like a triangle, created by deposition of sediment that is carried by a river and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or (more rare ...

swamp A swamp is a forested wetland.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Swamps are considered to be transition zones because both land and water play a role in ...

s. The trees composing this Pennsylvanian forest included ''

Cordaites ''Cordaites'' is an important genus of extinct gymnosperms which grew on wet ground similar to the Everglades in Florida. Brackish water mussels and crustacea are found frequently between the roots of these trees. The fossils are found in rock s ...

'',

scale tree Lepidodendrales (from the Greek for "scale tree") were primitive, vascular, heterosporous, arborescent (tree-like) plants related to present day lycopsids. Members of Lepidodendrales are the best understood of the fossil lycopsids due to the vast ...

s, and seal trees. Some of these trees could grow over 100 feet high. The rest of the flora included scouring rushes, ''

Sphenophyllum ''Sphenophyllum'' is a genus in the order Sphenophyllales Sphenophyllales is an extinct order of articulate land plants and a sister group to the present-day Equisetales (horsetails). They are fossils dating from the Devonian to the Triassi ...

'',

fern A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes except t ...

s, and

seed ferns A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosperm pl ...

. The fossils they left behind include casts, molds, compressions, and even entire plant preserved in nodules.

River A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...

s running through the ancient swamps swept leaves and plant debris out to sea. The environment of Pennsylvanian Illinois was comparable to the modern Amazon River delta. Almost every Pennsylvanian deposit in Illinois preserves evidence of this ancient flora and such deposits are located in almost every region of the state. The vegetation of these ancient swamps became Illinois' modern

coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when dea ...

deposits. More than 130 kinds of

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...

s inhabited the Pennsylvanian Mazon Creek area. The insects are typical for what one would expect to see in a woodland near the sea. Some of these insects were similar to modern forms like

dragonflies A dragonfly is a flying insect belonging to the infraorder Anisoptera below the order Odonata. About 3,000 extant species of true dragonfly are known. Most are tropical, with fewer species in temperate regions. Loss of wetland habitat threa ...

, roaches, and

damselflies Damselflies are flying insects of the suborder Zygoptera in the order Odonata. They are similar to dragonflies, which constitute the other odonatan suborder, Anisoptera, but are smaller and have slimmer bodies. Most species fold the wings along ...

. Others are unlike anything alive today. Other terrestrial invertebrate life included early

scorpion Scorpions are predatory arachnids of the order Scorpiones. They have eight legs, and are easily recognized by a pair of grasping pincers and a narrow, segmented tail, often carried in a characteristic forward curve over the back and always end ...

s and a variety of primitive

spider Spiders ( order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species ...

s. Mazon Creek vertebrates included the small amphibian '' Amphibamus grandiceps'', which may be a relative of the amphibian lineage that led up to

frogs A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura (ανοὐρά, literally ''without tail'' in Ancient Greek). The oldest fossil "proto-frog" ''Triadobatrachus'' is ...

. Amphibians as large as ten feet in length lived in these swamps. Some early vertebrates preserved in the Mazon Creek's

concretionary A concretion is a hard, compact mass of matter formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. Concretions are often ovoid or spherical in shape, although irregular ...

nodules have fossilized soft tissue. A gap in the local rock record spans the entire Permian period, so there are no rocks of this age in Illinois in which fossils could have been preserved. However, one notable local event following the Pennsylvanian was the meteor impact that occurred near modern

Des Plaines Des Plaines is a city in Cook County, Illinois, United States. Per the 2020 census, the population was 60,675. The city is a suburb of Chicago and is located just north of O'Hare International Airport. It is situated on and is named after the ...

. Another is the extinction of the trilobites at the end of the

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...

Mesozoic

Most of the Mesozoic era is also missing from the local rock record. This is because during that time sediments were generally being eroded away from Illinois rather than deposited. Nevertheless, a few Cretaceous deposits are known in the state. During the Cretaceous Illinois was home to foraminiferans. Contemporary local plants also left behind leaves that would later fossilize.

Cenozoic

Likewise, there are few rocks dating back to the ensuing Tertiary period of the Cenozoic era. Some wildlife from that time period were preserved in the far southern region of the state, but otherwise little is known about Tertiary Illinois. The fossil record does not become productive again until the

. The area where modern Peoria is situated was home to the Mississippi river two million years ago. At the same time, the area where the modern

University of Illinois at Champaign-Urbana The University of Illinois Urbana-Champaign (U of I, Illinois, University of Illinois, or UIUC) is a public land-grant research university in Illinois in the twin cities of Champaign and Urbana. It is the flagship institution of the University ...

stands was home to the Mahomet River. At that time the Mississippi River flowed through

Bureau Bureau ( ) may refer to: Agencies and organizations *Government agency *Public administration * News bureau, an office for gathering or distributing news, generally for a given geographical location * Bureau (European Parliament), the administrat ...

and

Henry Henry may refer to: People *Henry (given name) *Henry (surname) * Henry Lau, Canadian singer and musician who performs under the mononym Henry Royalty * Portuguese royalty ** King-Cardinal Henry, King of Portugal ** Henry, Count of Portugal, ...

counties. The Mahomet River joined it near

Havana Havana (; Spanish: ''La Habana'' ) is the capital and largest city of Cuba. The heart of the La Habana Province, Havana is the country's main port and commercial center.

. Illinois experienced its main periods of

glaciation A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betw ...

over the past 1.8 million years. These glaciers filled in the Mahomet River valley. The melting glaciers transported large amounts of sediment that filled in the original course of the Mississippi River, which took on its modern course. Other glacial melt water went on to form large lakes. The advance and retreat of Illinois' glaciers coincided with cooling and warming spells of climate. During the warm spells Illinois was home to animals like

jaguars The jaguar (''Panthera onca'') is a large cat species and the only living member of the genus ''Panthera'' native to the Americas. With a body length of up to and a weight of up to , it is the largest cat species in the Americas and the thi ...

peccaries A peccary (also javelina or skunk pig) is a medium-sized, pig-like hoofed mammal of the family Tayassuidae (New World pigs). They are found throughout Central and South America, Trinidad in the Caribbean, and in the southwestern area of North A ...

, and

armadillo Armadillos (meaning "little armored ones" in Spanish) are New World placental mammals in the order Cingulata. The Chlamyphoridae and Dasypodidae are the only surviving families in the order, which is part of the superorder Xenarthra, along wi ...

s. During cold spells Illinois was home to animals like

mammoth A mammoth is any species of the extinct elephantid genus ''Mammuthus'', one of the many genera that make up the order of trunked mammals called proboscideans. The various species of mammoth were commonly equipped with long, curved tusks and, ...

mastodon A mastodon ( 'breast' + 'tooth') is any proboscidean belonging to the extinct genus ''Mammut'' (family Mammutidae). Mastodons inhabited North and Central America during the late Miocene or late Pliocene up to their extinction at the end of th ...

s, and

Snowshoe hare The snowshoe hare (''Lepus americanus''), also called the varying hare or snowshoe rabbit, is a species of hare found in North America. It has the name "snowshoe" because of the large size of its hind feet. The animal's feet prevent it from sink ...

s also used to make their home in Illinois. The

Illinoian (stage) The Illinoian Stage is the name used by Quaternary geologists in North America to designate the period c.191,000 to c.130,000 years ago, during the middle Pleistocene, when sediments comprising the Illinoian Glacial Lobe were deposited. It precedes ...

glaciation occurred some 300,000 to 130,000 years ago. The last time glaciers covered Illinois was during the

Wisconsin glaciation The Wisconsin Glacial Episode, also called the Wisconsin glaciation, was the most recent glacial period of the North American ice sheet complex. This advance included the Cordilleran Ice Sheet, which nucleated in the northern North American Cor ...

25,000 years ago.

History

As far back as the late 1850s significant fossil discoveries were occurring in Illinois. At this time fossils were discovered in nodules discovered at natural rock exposures along the

in Grundy County. Early in the 20th century, J. H. Bretz and H. A. Lowenstam studied the Silurian fossil reef systems of the Chicago area following a decline in scientific attention paid to the famous fossil reefs of similar age near

Milwaukee Milwaukee ( ), officially the City of Milwaukee, is both the most populous and most densely populated city in the U.S. state of Wisconsin and the county seat of Milwaukee County. With a population of 577,222 at the 2020 census, Milwaukee is ...

Wisconsin Wisconsin () is a state in the upper Midwestern United States. Wisconsin is the 25th-largest state by total area and the 20th-most populous. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake M ...

. Later, during the 1920s, strip mining for

south of Braidwood generated piles of waste rock that would later become popular sites for fossil collection. These waste piles would later serve as the source for most Tully monster finds. During the late 1950s

found a fossil he could not identify at the strip mines near Braidwood. He took the specimen to Chicago's

Field Museum of Natural History The Field Museum of Natural History (FMNH), also known as The Field Museum, is a natural history museum in Chicago, Illinois, and is one of the largest such museums in the world. The museum is popular for the size and quality of its educational ...

. Researchers at the museum could not identify it either, and the specimen became known as Mr. Tully's monster. In 1966, Eugene Richardson, the Curator of Fossil Invertebrates of the Field Museum formally named the Tully monster ''

''. Finally, in 2016, scientists after reviewing over 1,000 fossilized Tully Monsters placed it in the same phylum as, and possibly related to,

lampreys Lampreys (sometimes inaccurately called lamprey eels) are an ancient extant lineage of jawless fish of the order Petromyzontiformes , placed in the superclass Cyclostomata. The adult lamprey may be characterized by a toothed, funnel-like s ...

. The Tully monster is one of the few officially designated state fossils to be endemic to its state of origins.

People

Births

John Bell Hatcher John Bell Hatcher (October 11, 1861 – July 3, 1904) was an American paleontologist and fossil hunter known as the "king of collectors" and best known for discovering ''Torosaurus'' and ''Triceratops'', two genera of dinosaurs described by Ot ...

was born in

Cooperstown Cooperstown is a village in and county seat of Otsego County, New York, United States. Most of the village lies within the town of Otsego, but some of the eastern part is in the town of Middlefield. Located at the foot of Otsego Lake in the C ...

on October 11,

1861 Statistically, this year is considered the end of the whale oil industry and (in replacement) the beginning of the petroleum oil industry. Events January–March * January 1 ** Benito Juárez captures Mexico City. ** The first steam-p ...

. *

Pierce Brodkorb William Pierce Brodkorb (September 29, 1908, Chicago – July 18, 1992, Gainesville, Florida) was an American ornithologist and paleontologist. Interested in birds since childhood, he was taught to prepare birds at the age of 16. Later, he rec ...

was born in Chicago on September 29,

1908 Events January * January 1 – The British ''Nimrod'' Expedition led by Ernest Shackleton sets sail from New Zealand on the ''Nimrod'' for Antarctica. * January 3 – A total solar eclipse is visible in the Pacific Ocean, and is the 46 ...

Charles Repenning Charles Albert Repenning (August 4, 1922 in Oak Park, Illinois – January 5, 2005 in Lakewood, Colorado) was an American paleontologist and zoologist noted for his work on shrews, fossil rodents, modern pinnipeds and their extinct relatives, ...

was born in Oak Park on August 4,

1922 Events January * January 7 – Dáil Éireann (Irish Republic), Dáil Éireann, the parliament of the Irish Republic, ratifies the Anglo-Irish Treaty by 64–57 votes. * January 10 – Arthur Griffith is elected President of Dáil Éirean ...

Frederick Schram Frederick Robert Schram (born August 11, 1943, in Chicago, Illinois, Chicago, Illinois) is an Americans, American palaeontologist and carcinologist. He received his Bachelor of Science, B.S. in biology from Loyola University Chicago in 1965, and ...

was born in Chicago on August 11,

1943 Events Below, the events of World War II have the "WWII" prefix. January * January 1 – WWII: The Soviet Union announces that 22 German divisions have been encircled at Stalingrad, with 175,000 killed and 137,650 captured. * January 4 – ...

. *

Sue Hendrickson Susan Hendrickson (born December 2, 1949) is an American explorer and fossil collector. Hendrickson is best known for her discovery of the remains of a ''Tyrannosaurus rex'' in South Dakota on August 12, 1990 in the Cheyenne River Reservation. H ...

was born in Chicago on December 2,

1949 Events January * January 1 – A United Nations-sponsored ceasefire brings an end to the Indo-Pakistani War of 1947. The war results in a stalemate and the division of Kashmir, which still continues as of 2022. * January 2 – Luis ...

. *

Paul Sereno Paul Callistus Sereno (born October 11, 1957) is a professor of paleontology at the University of Chicago and a National Geographic "explorer-in-residence" who has discovered several new dinosaur species on several continents, including at sites ...

was born in Chicago on October 11,

1957 1957 ( MCMLVII) was a common year starting on Tuesday of the Gregorian calendar, the 1957th year of the Common Era (CE) and ''Anno Domini'' (AD) designations, the 957th year of the 2nd millennium, the 57th year of the 20th century, and the 8th y ...

. *

Stephen L. Brusatte Stephen Louis Brusatte (born April 24, 1984) is an American paleontologist and evolutionary biologist, who specializes in the anatomy and evolution of dinosaurs. He was educated at the University of Chicago for his BS degree, at the University of ...

was born in

Ottawa Ottawa (, ; Canadian French: ) is the capital city of Canada. It is located at the confluence of the Ottawa River and the Rideau River in the southern portion of the province of Ontario. Ottawa borders Gatineau, Quebec, and forms the core ...

on April 24,

1984 Events January * January 1 – The Bornean Sultanate of Brunei gains full independence from the United Kingdom, having become a British protectorate in 1888. * January 7 – Brunei becomes the sixth member of the Association of Southeast A ...

Deaths

Bryan Patterson Bryan Patterson (born 10 March 1909 in London; died 1 December 1979 in Chicago) was an American paleontologist at the Field Museum of Natural History in Chicago. Life and career Bryan Patterson was the son of the soldier, engineer and author ...

died in Chicago on December 1,

1979 Events January * January 1 ** United Nations Secretary-General Kurt Waldheim heralds the start of the ''International Year of the Child''. Many musicians donate to the ''Music for UNICEF Concert'' fund, among them ABBA, who write the song ...

Natural history museums

Burpee Museum of Natural History The Burpee Museum of Natural History is located along the Rock River in downtown Rockford, Illinois, United States, at 737 North Main Street. Museum history The museum was created as a Works Progress Administration project. It was established ...

, Rockford * Elgin Public Museum, Elgin *

, Chicago *Jurica-Suchy Nature Museum,

Benedictine University Benedictine University is a private Roman Catholic university in Lisle, Illinois. It was founded in 1887 as St. Procopius College by the Benedictine monks of St. Procopius Abbey in the Pilsen community on the West Side of Chicago. The institu ...

, Lisle *

Illinois State Museum The Illinois State Museum features the life, land, people and art of the State of Illinois. The headquarters museum is located on Spring and Edwards Streets, one block southwest of the Illinois State Capitol, in Springfield. There are three satell ...

, Springfield *

Midwest Museum of Natural History The Midwest Museum of Natural History was a 501(c)3 organization located in Sycamore, Illinois, United States. In 1875, the structure was built as the home of the Universalist Church in Sycamore. In the 1920s the building underwent dramatic change ...

, Sycamore (closed) *

Peggy Notebaert Nature Museum The Peggy Notebaert Nature Museum is a natural history museum located in Chicago, Illinois, and operated by the Chicago Academy of Sciences. The museum traces its history to the founding of the academy in 1857. After a century at a nearby locati ...

, Chicago

Notable clubs and associations

* Earth Science Club of Northern Illinois * International Fossil Exposition

Footnotes

References

Animals Past and Present
University of Illinois Extension. Accessed August 3, 2012.
Dinosaur FAQ
Tour Through Time. Field Museum. Accessed August 3, 2012. * * Kolata, Dennis R
The Trilobite—An Early Inhabitant of Illinois
Geobit 6. Illinois State Geological Survey. 2004. 2 pp. Accessed August 3, 2012. * Mayor, Adrienne. ''Fossil Legends of the First Americans''. Princeton University Press. 2005. . * Mikulic, Donald G. The Reefs that Made Milwaukee Famous. ''Geoscience Wisconsin''. Volume 18. 2001. * Mikulic, D.G. and Kluessendorf, J
Illinois’ State Fossil— ''Tullimonstrum gregarium''
Geobit 5. Illinois State Geological Survey. 2004. 2 pp. Accessed August 3, 2012. * * Theodor, Jessica, Judy Scotchmoor, Dale Springer. July 1, 2005.
Illinois, US

The Paleontology Portal
Accessed October 1, 2012. * Vaiden, Robert C
Build Illinois: The Last 500 Million Years
Geonote 4. Illinois State Geological Survey. 2004. 12 pp. Accessed August 3, 2012.

External links

Geologic units in Illinois

Mazon Creek Fossils

Paleoportal: Illinois
{{Paleontology in the United States

Natural history of Illinois Science and technology in Illinois

Prehistory

Ordovician

Silurian

Devonian

Mississippian

Pennsylvanian

Mesozoic

Cenozoic

History

People

Births

Deaths

Natural history museums

Notable clubs and associations

See also

Footnotes

References

External links