![Map of USA IA](https://upload.wikimedia.org/wikipedia/commons/6/60/Map_of_USA_IA.svg)
Paleontology in Iowa 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.
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
state of
Iowa
Iowa () is a state in the Midwestern region of the United States, bordered by the Mississippi River to the east and the Missouri River and Big Sioux River to the west. It is bordered by six states: Wisconsin to the northeast, Illinois to the ...
. The paleozoic
fossil record
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in ...
of Iowa spans from 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 ...
to
Mississippian.
During the early
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 ' ...
Iowa was covered by a shallow
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, ...
that would later be home to creatures like
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 ...
,
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 ...
,
cephalopods
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, an ...
,
corals
Corals are marine invertebrates within the class (biology), class Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important C ...
,
fishes
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...
, and
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 ...
. Later in the Paleozoic, this sea left the state, but a new one covered Iowa during the early
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 ...
. As this sea began to withdraw a new
subtropical
The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Geographical z ...
coastal plain
A coastal plain is flat, low-lying land adjacent to a sea coast. A fall line commonly marks the border between a coastal plain and a piedmont area. Some of the largest coastal plains are in Alaska and the southeastern United States. The Gulf Coa ...
environment which was home to
duck-billed dinosaurs
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
spread across the state. Later this plain was submerged by the rise of the
Western Interior Seaway
The Western Interior Seaway (also called the Cretaceous Seaway, the Niobraran Sea, the North American Inland Sea, and the Western Interior Sea) was a large inland sea that split the continent of North America into two landmasses. The ancient sea, ...
, where
plesiosaurs
The Plesiosauria (; Greek: πλησίος, ''plesios'', meaning "near to" and ''sauros'', meaning "lizard") or plesiosaurs are an order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia.
Plesiosaurs first appeared ...
lived. The early
Cenozoic
The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configura ...
is missing from the local rock record, but 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 ...
evidence indicates that
glaciers
A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as ...
entered the state, which was home to
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, ...
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 ...
.
Prehistory
![Atrypa reticularis00](https://upload.wikimedia.org/wikipedia/commons/b/bc/Atrypa_reticularis00.gif)
![Fossil Hexagonaria mirabilis MHNL](https://upload.wikimedia.org/wikipedia/commons/7/79/Fossil_Hexagonaria_mirabilis_MHNL.jpg)
No
Precambrian
The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...
fossils are known from Iowa, so the fossil record does not begin until 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 ' ...
. During the early Paleozoic, most of Iowa was submerged by an ancient
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, ...
. The bottom of this sea was home to creatures like
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 ...
,
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 ...
,
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,
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 ...
s,
mollusc
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...
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.
The life of
Mississippian Iowa included
blastoids, brachiopods, coral, crinoids, and
starfish
Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea (). Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish ...
.
Blastoids from this time period left behind remains in what is now the southeastern part of the state.
Brachiopods from this time period left behind remains in what is now the southeastern
Benton County and the southeastern part of the state.
The Benton County brachiopods included ''
Atrypa
''Atrypa'' is a genus of brachiopod with shells round to short egg-shaped, covered with many fine radial ridges (or costae), that split further out and growth lines perpendicular to the costae and 2-3 times wider spaced. The pedunculate valve is ...
'' and ''
Spirifer
''Spirifer'' is a genus of marine brachiopods belonging to the order Spiriferida and family Spiriferidae. Species belonging to the genus lived from the Middle Ordovician (Sandbian) through to the Middle Triassic (Carnian) with a global distribu ...
''.
Corals of Mississippian Iowa included the colonial ''
Hexagonaria'' of southeastern Benton County.
Crinoids left behind remains in what are now the
Le Grand area and the southeastern part of the state.
Some of the Le Grand crinoids are rare in other places.
Some of the Le Grand starfishes are rare in other places.
Vertebrate life included
fishes
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...
. Fish teeth of this time period fossilized in the southeastern part of the state.
As the Paleozoic drew to a close, Iowa's sea's dried up. For a significant length of time sediments were being eroded away from the state rather than deposited.
During the early
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 ...
, a new sea covered Iowa, and sediment deposition resumed. As this sea withdrew later in the Mesozoic Iowa became a
subtropical
The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Geographical z ...
coastal plain
A coastal plain is flat, low-lying land adjacent to a sea coast. A fall line commonly marks the border between a coastal plain and a piedmont area. Some of the largest coastal plains are in Alaska and the southeastern United States. The Gulf Coa ...
with
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 interspersed throughout.
Later,
dinosaurs
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
lived and left behind fossil remains in Iowa, although the record of their presence is scant. Further, dinosaur fossils have been found in neighboring states like
Minnesota
Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over to ...
,
Missouri
Missouri is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it is bordered by eight states (tied for the most with Tennessee ...
,
Nebraska
Nebraska () is a state in the Midwestern region of the United States. It is bordered by South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Kansas to the south; Colorado to the southwe ...
, and
South Dakota
South Dakota (; Sioux language, Sioux: , ) is a U.S. state in the West North Central states, North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Lakota people, Lakota and Dakota peo ...
. There were no barriers that would have prevented the dinosaurs of this region from crossing what are now the state boundaries.
No
Jurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...
dinosaur fossils are known from Iowa, although the Iowan Fort Dodge Formation is the same age as the dinosaur-bearing deposits of the western states.
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...
deposits cover a wider area of Iowa than those of
Jurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...
age.
Between 95 and 100 million years ago, areas of Iowa were covered by a complex of
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 flowing toward the west through
floodplains
A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...
and coastal lowlands. These deposited the sediments that are now called the
Dakota Formation
The Dakota is a sedimentary geologic unit name of formation and group rank in Midwestern North America. The Dakota units are generally composed of sandstones, mudstones, clays, and shales deposited in the Mid-Cretaceous opening of the Western Int ...
, the oldest Cretaceous rocks in the state. Global temperatures were elevated and Iowa was richly vegetated by a subtropical flora.
Unlike the Jurassic deposits, dinosaur fossils were preserved in these rocks.
At least one kind of primitive
hadrosaur
Hadrosaurids (), or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The ornithopod family, which includ ...
that left behind remains in Iowa was more than 30 feet long.
Gradually over time the rivers depositing the Dakota Formation sediments were submerged by the northward expansion of the
Western Interior Seaway
The Western Interior Seaway (also called the Cretaceous Seaway, the Niobraran Sea, the North American Inland Sea, and the Western Interior Sea) was a large inland sea that split the continent of North America into two landmasses. The ancient sea, ...
.
This body of water deposited shale and chalk.
Plesiosaurs
The Plesiosauria (; Greek: πλησίος, ''plesios'', meaning "near to" and ''sauros'', meaning "lizard") or plesiosaurs are an order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia.
Plesiosaurs first appeared ...
lived in this sea and left behind fossils in several regions of Iowa.
Northwestern Iowa's
quartzite
Quartzite is a hard, non- foliated metamorphic rock which was originally pure quartz sandstone.Essentials of Geology, 3rd Edition, Stephen Marshak, p 182 Sandstone is converted into quartzite through heating and pressure usually related to tect ...
rocks may have attracted long-necked
elasmosaurs as a source of
gastroliths
A gastrolith, also called a stomach stone or gizzard stone, is a rock held inside a gastrointestinal tract. Gastroliths in some species are retained in the muscular gizzard and used to grind food in animals lacking suitable grinding teeth. In oth ...
.
Outside of Iowa the same deposits have preserved animals like
mosasaurs
Mosasaurs (from Latin ''Mosa'' meaning the 'Meuse', and Greek ' meaning 'lizard') comprise a group of extinct, large marine reptiles from the Late Cretaceous. Their first fossil remains were discovered in a limestone quarry at Maastricht on the ...
and
pterosaurs
Pterosaurs (; from Greek ''pteron'' and ''sauros'', meaning "wing lizard") is an extinct clade of flying reptiles in the order, Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 to ...
.
During the mid-
Campanian
The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campanian s ...
, about 75 million years ago, an
asteroid
An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere.
...
roughly 1.5 miles in diameter struck the earth from the southeast near the east coast of the Western Interior Seaway. The
impact site is located near the modern site of a town called
Manson on the western half of the state. This event would have had a catastrophic impact on life on both land and sea for hundreds of miles around the crater, which had a diameter of roughly 22 miles. It scattered rock debris all the way to
South Dakota
South Dakota (; Sioux language, Sioux: , ) is a U.S. state in the West North Central states, North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Lakota people, Lakota and Dakota peo ...
and triggered huge tsunamis. However, despite the devastation South Dakotan fossils revealed that life recovered from the Iowan impact until the
Cretaceous-Paleogene extinction event, itself likely caused by an extraterrestrial impact down in the
Yucatan Peninsula of
Mexico
Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
.
During the early part of the
Cenozoic
The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configura ...
era, sediments were being eroded away from Iowa rather than deposited.
Late in the Cenozoic
glaciers
A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as ...
intruded southward into Iowa. As they melted they left behind new sedimentary deposits. At this time Iowa was home to
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, ...
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 ...
, whose remains were preserved in a wide variety of locations in the state.
During the glaciations of 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 ...
over the past 2.5 million years the glaciers transported and deposited fossils eroded from Cretaceous sediments. Some of the Cretaceous fossils to be redeposited in this manner included
plesiosaur
The Plesiosauria (; Greek: πλησίος, ''plesios'', meaning "near to" and ''sauros'', meaning "lizard") or plesiosaurs are an order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia.
Plesiosaurs first appeared ...
bones,
shark
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 Selachimo ...
teeth, and two dinosaur bones. The dinosaur bones reworked by glacial activity are the best in the state.
History
Indigenous interpretations
Nahurac were spirit animals that the
Pawnees believed inhabited certain local
hills
A hill is a landform that extends above the surrounding terrain. It often has a distinct summit.
Terminology
The distinction between a hill and a mountain is unclear and largely subjective, but a hill is universally considered to be not as ...
or mounds.
Geographical features were likely regarded as nahurac sites because of the bones of strange extinct wildlife preserved in their sediments.
A jawbone of the fish ''
Saurocephalus lanciformis
''Saurocephalus'' (from el, σαῦρος , 'lizard' and el, κεφαλή 'head') is an extinct genus of ray-finned fishes within the family Saurodontidae.Maisey, J. G.1991. ''Santana Fossils, an Illustrated Atlas''. New Jersey, T.F.H. Public ...
'' was found in a cave near where the
Missouri
Missouri is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it is bordered by eight states (tied for the most with Tennessee ...
and
Soldier
A soldier is a person who is a member of an army. A soldier can be a conscripted or volunteer enlisted person, a non-commissioned officer, or an officer.
Etymology
The word ''soldier'' derives from the Middle English word , from Old French ...
rivers combine, however since this fish is known only from the
Niobrara chalk
The Niobrara Formation , also called the Niobrara Chalk, is a geologic formation in North America that was deposited between 87 and 82 million years ago during the Coniacian, Santonian, and Campanian stages of the Late Cretaceous. It is compose ...
in
Kansas
Kansas () is a state in the Midwestern United States. Its capital is Topeka, and its largest city is Wichita. Kansas is a landlocked state bordered by Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to the ...
and western
Nebraska
Nebraska () is a state in the Midwestern region of the United States. It is bordered by South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Kansas to the south; Colorado to the southwe ...
it was likely brought to the cave by a
Native American.
The cave may have been used as a place to commune with nahurac by the Pawnee.
Such long-distance transportation of fossils was not unusual for Native Americans.
Scientific research
![Gryposaurus-notabilis jconway](https://upload.wikimedia.org/wikipedia/commons/7/70/Gryposaurus-notabilis_jconway.png)
In August 1804,
Meriwether Lewis
Meriwether Lewis (August 18, 1774 – October 11, 1809) was an American explorer, soldier, politician, and public administrator, best known for his role as the leader of the Lewis and Clark Expedition, also known as the Corps of Discovery, with ...
of the
Lewis and Clark Expedition
The Lewis and Clark Expedition, also known as the Corps of Discovery Expedition, was the United States expedition to cross the newly acquired western portion of the country after the Louisiana Purchase. The Corps of Discovery was a select gro ...
noted the discovery of a fossil fish jawbone along the
Missouri River in what is now
Harrison County.
This specimen was the first known fossil fish discovery in the
Niobrara chalk
The Niobrara Formation , also called the Niobrara Chalk, is a geologic formation in North America that was deposited between 87 and 82 million years ago during the Coniacian, Santonian, and Campanian stages of the Late Cretaceous. It is compose ...
. The specimen is also the only fossil collected by the Lewis and Clark Expedition that still exists. It is curated by the
Academy of Natural Sciences
The Academy of Natural Sciences of Drexel University, formerly the Academy of Natural Sciences of Philadelphia, is the oldest natural science research institution and museum in the Americas. It was founded in 1812, by many of the leading natura ...
in Philadelphia
Philadelphia, often called Philly, is the largest city in the Commonwealth of Pennsylvania, the sixth-largest city in the U.S., the second-largest city in both the Northeast megalopolis and Mid-Atlantic regions after New York City. Sinc ...
as ANSP 5516.
In 1824, Dr.
Richard T. Harlan would formally name the species that left the jaw ''
Saurocephalus lanciformis
''Saurocephalus'' (from el, σαῦρος , 'lizard' and el, κεφαλή 'head') is an extinct genus of ray-finned fishes within the family Saurodontidae.Maisey, J. G.1991. ''Santana Fossils, an Illustrated Atlas''. New Jersey, T.F.H. Public ...
'', but mistook it for the remains of a
marine reptile
Marine reptiles are reptiles which have become secondarily adapted for an aquatic or semiaquatic life in a marine environment.
The earliest marine reptile mesosaurus (not to be confused with mosasaurus), arose in the Permian period during the ...
.
Richard Harlan believed the jaw was from an "
Enalio Saurian". This was imagined to be a marine lizard resembling
plesiosaurs
The Plesiosauria (; Greek: πλησίος, ''plesios'', meaning "near to" and ''sauros'', meaning "lizard") or plesiosaurs are an order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia.
Plesiosaurs first appeared ...
and
ichthyosaurs
Ichthyosaurs (Ancient Greek for "fish lizard" – and ) are large extinct marine reptiles. Ichthyosaurs belong to the order known as Ichthyosauria or Ichthyopterygia ('fish flippers' – a designation introduced by Sir Richard Owen in 1842, alt ...
. In 1830
Isaac Hays
Isaac Hays (1796 – 1879) was an American ophthalmologist, medical ethicist, and naturalist. A founding member of the American Medical Association, and the first president of the Philadelphia Ophthalmological Society, Hays published the fir ...
described a new species of fossil fish in
New Jersey
New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delaware ...
he named ''
Saurodon leanus
''Saurodon'' (from el, σαῦρος , 'lizard' and el, ὀδούς 'tooth') is an extinct genus of ichthyodectiform fish from the Cretaceous.
''Saurodon leanus'' is known to occur as early as the late Coniacian through the Santonian, in the ...
''. The new find by Hays was similar enough to ''Saurocephalus'' that he was able to correct Harlan's misidentification.
In 1856
Joseph Leidy
Joseph Mellick Leidy (September 9, 1823 – April 30, 1891) was an American paleontologist, parasitologist and anatomist.
Leidy was professor of anatomy at the University of Pennsylvania, later was a professor of natural history at Swarthmore ...
had identified once more as a fish and dated it to the
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...
period.
In 1858
W. James Hall, the
New York
New York most commonly refers to:
* New York City, the most populous city in the United States, located in the state of New York
* New York (state), a state in the northeastern United States
New York may also refer to:
Film and television
* '' ...
state geologist, made an early major discovery in the history of Iowa paleontology. He discovered
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 ...
fossils about a mile north of
Le Grand. The local limestone preserved these fossils in unusually great detail.
Later, during the 1890s, amateur fossil collector B. H. Bean began collecting in Iowa. Over time he became an expert on the state's middle Mississippian life.
In 1928, a
femur
The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with ...
was discovered in the
Missouri River bluffs, not far from
Decatur, Nebraska
Decatur is a village in Burt County, Nebraska, United States, adjacent to the upper Missouri River. The population was 481 at the 2010 census. This town is named after one of its incorporators, Stephen Decatur. It developed around a trading post ...
. Although it was impossible to identify the specimen as belonging to an individual species, the femur's anatomy was informative enough that paleontologists could identify it as belonging to an
ornithopod
Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (), that started out as small, bipedal running grazers and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous world ...
about 32 feet long. This was the first scientifically documented dinosaur bone discovered in the
Dakota Formation
The Dakota is a sedimentary geologic unit name of formation and group rank in Midwestern North America. The Dakota units are generally composed of sandstones, mudstones, clays, and shales deposited in the Mid-Cretaceous opening of the Western Int ...
.
In 1930 B. H. Bean made another big discovery when he obtained a limestone block that was being removed from a quarry. This single block preserved 183 individual
starfish
Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea (). Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish ...
, which is significant because starfish fossils are very uncommon, even in the local area.
Later in the 1930s, a Materials Inspector working for the Iowa Highway Commission named John Holdefer noticed a fossil bone on a conveyor in a
Plymouth County gravel
Gravel is a loose aggregation of rock fragments. Gravel occurs naturally throughout the world as a result of sedimentary and erosive geologic processes; it is also produced in large quantities commercially as crushed stone.
Gravel is classifi ...
pit, not far from
Akron
Akron () is the fifth-largest city in the U.S. state of Ohio and is the county seat of Summit County. It is located on the western edge of the Glaciated Allegheny Plateau, about south of downtown Cleveland. As of the 2020 Census, the city prop ...
. He took the four inch long, partially weathered specimen home where it was kept on a shelf and sometimes used as a doorstop. Its scientific value went unrecognized for years.
In 1982, Brian J. Witzke discovered a piece of fossil bone in
Guthrie County. The specimen had been entombed by a Dakota Formation river gravel deposit. Examination under a
microscope
A microscope () is a laboratory instrument used to examine objects that are too small to be seen by the naked eye. Microscopy is the science of investigating small objects and structures using a microscope. Microscopic means being invisibl ...
revealed that the bone was dense with
blood vessels
The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away f ...
in life, a characteristic of dinosaur bone. This was the first confirmed dinosaur fossil in the state.
After Gillette's dinosaur vertebra discovery, Doris Michaelson, daughter of John Holdefer, read a newspaper article on Iowa's dinosaur fossil. Suspecting the fossil formerly used as a doorstop may be significant, she took the bone to the Geological Survey Bureau to see if it could be identified. The Geological Survey affirmed it to be a dinosaur vertebra, likely from a
hadrosaur
Hadrosaurids (), or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The ornithopod family, which includ ...
.
On September 7, 2000, ''
The Des Moines Register
''The Des Moines Register'' is the daily morning newspaper of Des Moines, Iowa.
History Early period
The first newspaper in Des Moines was the ''Iowa Star''. In July 1849, Barlow Granger began the paper in an abandoned log cabin by the junctio ...
'' reported the discovery of the state's first identifiable dinosaur fossil. The discovery was made by a resident of Dickinson County named Charlie Gillette. The darkly colored, three inch long fossil originated among landscaping gravel from a nearby pit. He showed the specimen to his uncle, Jack Neuzil. Neuzil was a retired teacher and was interested in dinosaurs. He thought the bone might be a dinosaur vertebra. His suspicions were later confirmed by a professional paleontologist.
In 2015, paleontologists discovered the remains of a giant
Megalograptid eurypterid
Eurypterids, often informally called sea scorpions, are a group of extinct arthropods that form the Order (biology), order Eurypterida. The earliest known eurypterids date to the Darriwilian stage of the Ordovician period 467.3 Myr, million yea ...
in the
middle Ordovician
The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya.
The ...
Winneshiek lagerstätte
The Winneshiek Shale (originally the Winneshiek Lagerstätte) is a Middle Ordovician (Darriwilian-age) geological formation in Iowa. The formation is restricted to the Decorah crater, an impact crater near Decorah, Iowa. Despite only being discove ...
near the town of Decorah.
It was named ''Pentecopterus decorahensis,'' named after the
penteconter
The penteconter (alt. spelling pentekonter, pentaconter, pentecontor or pentekontor; el, πεντηκόντερος, ''pentēkónteros'', "fifty-oared"), plural penteconters, was an ancient Greek galley in use since the archaic period.
In an ...
.
The creature was one of the largest arthropods to have ever lived, with a max length of 5 feet, 7 inches (2 meters).
The shale also contains the fossils of
giant conodonts,
''
Astraspis
''Astraspis'' ('star shield') is an extinct genus of primitive jawless fish from the Ordovician of Central North America including the Harding Sandstone of Colorado and Bighorn Mountains of Wyoming. It is also known from Bolivia.Sacabambaspis j ...
'', giant algae,
phyllocarids,
and possibly the oldest known
Thylacocephala
The Thylacocephala (from the Greek language, Greek or ', meaning "Bag, pouch", and or ' meaning "head") are a unique grouping of extinct probable Mandibulata, mandibulate arthropods, that have been considered by some researchers as having possi ...
n.
Protected areas
* Rockford Iowa Fossil and Prairie Park
People
*
Edwin Harris Colbert
Edwin Harris "Ned" Colbert (September 28, 1905 – November 15, 2001)O'Connor, Anahad ''The New York Times'', November 25, 2001. was a distinguished American vertebrate paleontologist and prolific researcher and author.
Born in Clarinda, Iowa, he ...
was born in
Clarinda on September 28,
1905
As the second year of the massive Russo-Japanese War begins, more than 100,000 die in the largest world battles of that era, and the war chaos leads to the 1905 Russian Revolution against Nicholas II of Russia (Shostakovich's 11th Symphony i ...
.
*
Carroll Lane Fenton
Carroll Lane Fenton (February 12, 1900, Butler County, Iowa – November 16, 1969, New Brunswick, New Jersey) was a geologist, paleontologist, neoichnologist, and historian of science. Fenton was the author and illustrator of numerous books o ...
was born in
Butler County on 12 February,
1900
As of March 1 ( O.S. February 17), when the Julian calendar acknowledged a leap day and the Gregorian calendar did not, the Julian calendar fell one day further behind, bringing the difference to 13 days until February 28 ( O.S. February 15), 2 ...
.
*
Mildred Adams Fenton
Mildred Adams Fenton (November 14, 1899 – December 7, 1995) trained in paleontology and geology at the University of Iowa. She coauthored dozens of general science books with her husband, Carroll Lane Fenton, including ''Records of Evolution' ...
was born in
West Branch West Branch may refer to:
Communities
* West Branch, Iowa, city in Cedar and Johnson counties
* West Branch, Michigan, city in Ogemaw County
* West Branch, New Brunswick, in the Local Service District of Weldford Parish
* West Branch River John, i ...
on 14 November,
1899
Events January 1899
* January 1
** Spanish rule ends in Cuba, concluding 400 years of the Spanish Empire in the Americas.
** Queens and Staten Island become administratively part of New York City.
* January 2 –
**Bolivia sets up a c ...
.
*
Remington Kellogg
Arthur Remington Kellogg (5 October 1892 – 8 May 1969) was an American naturalist and a director of the United States National Museum. His work focused on marine mammals.
Early life and career
Kellogg was born in Davenport, Iowa, and quick ...
was born in
Davenport
Davenport may refer to:
Places Australia
*Davenport, Northern Territory, a locality
* Hundred of Davenport, cadastral unit in South Australia
**Davenport, South Australia, suburb of Port Augusta
**District Council of Davenport, former local govern ...
on 5 October,
1892
Events
January–March
* January 1 – Ellis Island begins accommodating immigrants to the United States.
* February 1 - The historic Enterprise Bar and Grill was established in Rico, Colorado.
* February 27 – Rudolf Diesel applies for ...
.
*
John Campbell Merriam
John Campbell Merriam (October 20, 1869 – October 30, 1945) was an American paleontologist, educator, and conservationist. The first vertebrate paleontologist on the West Coast of the United States, he is best known for his taxonomy of ver ...
was born in
Hopkinton on October 20,
1869
Events
January–March
* January 3 – Abdur Rahman Khan is defeated at Tinah Khan, and exiled from Afghanistan.
* January 5 – Scotland's oldest professional football team, Kilmarnock F.C., is founded.
* January 20 – E ...
.
Natural history museums
*Battle Hill Museum of Natural History,
Battle Creek
Battle Creek is a city in the U.S. state of Michigan, in northwest Calhoun County, at the confluence of the Kalamazoo and Battle Creek rivers. It is the principal city of the Battle Creek, Michigan Metropolitan Statistical Area (MSA), which encom ...
(closed)
*
Museum of Natural History
A natural history museum or museum of natural history is a scientific institution with natural history collections that include current and historical records of animals, plants, fungi, ecosystems, geology, paleontology, climatology, and more. ...
,
University of Iowa
The University of Iowa (UI, U of I, UIowa, or simply Iowa) is a public university, public research university in Iowa City, Iowa, United States. Founded in 1847, it is the oldest and largest university in the state. The University of Iowa is org ...
*
Putnam Museum
The Putnam Museum and Science Center, formerly Davenport Academy of Natural Sciences, is a museum of history and natural science and a science center in Davenport, Iowa, United States. The museum was founded in 1867, and was one of the first mus ...
,
Davenport
Davenport may refer to:
Places Australia
*Davenport, Northern Territory, a locality
* Hundred of Davenport, cadastral unit in South Australia
**Davenport, South Australia, suburb of Port Augusta
**District Council of Davenport, former local govern ...
*
University Museum
A university museum is a repository of collections run by a university, typically founded to aid teaching and research within the institution of higher learning. The Ashmolean Museum at the University of Oxford in England is an early example, o ...
,
University of Northern Iowa
The University of Northern Iowa (UNI) is a public university in Cedar Falls, Iowa. UNI offers more than 90 majors across the colleges of Business Administration, Education, Humanities, Arts, and Sciences, Social and Behavioral Sciences and grad ...
,
Cedar Falls
Notable clubs and associations
* The Mid-America Paleontological Association
See also
*
Paleontology in Illinois The location of the state of Illinois
Paleontology in Illinois refers to paleontological research occurring within or conducted by people from the U.S. state of Illinois. Scientists have found that Illinois was covered by a sea during the Paleozo ...
*
Paleontology in Minnesota
Paleontology in Minnesota refers to paleontological research occurring within or conducted by people from the U.S. state of Minnesota. The geologic record of Minnesota spans from Precambrian to recent with the exceptions of major gaps including the ...
*
Paleontology in Missouri
Paleontology in Missouri refers to paleontological research occurring within or conducted by people from the U.S. state of Missouri. The geologic column of Missouri spans all of geologic history from the Precambrian to present with the exception ...
*
Paleontology in Nebraska The location of the state of Nebraska
Paleontology in Nebraska refers to paleontological research occurring within or conducted by people from the U.S. state of Nebraska. Nebraska is world-famous as a source of fossils. During the early Paleozoic ...
*
Paleontology in South Dakota
Paleontology in South Dakota refers to paleontological research occurring within or conducted by people from the U.S. state of South Dakota. South Dakota is an excellent source of fossils as finds have been widespread throughout the state. During ...
*
Paleontology in Wisconsin
Paleontology in Wisconsin refers to paleontological research occurring within or conducted by people from the U.S. state of Wisconsin. The state has fossils from the Precambrian, much of the Paleozoic, and the later part of the Cenozoic. Most of th ...
Footnotes
References
* Everhart, M. J. 2005. ''Oceans of Kansas - A Natural History of the Western Interior Sea''. Indiana University Press, 320 pp.
*
* Mayor, Adrienne. ''Fossil Legends of the First Americans''. Princeton University Press. 2005. .
*
* Springer, Dale, Judy Scotchmoor. July 1, 2005.
Iowa, USThe Paleontology Portal Accessed September 21, 2012.
* Witzke, Brian J. The Age of Dinosaurs in Iowa. ''Iowa Geology''. Number 26. 2001. Pages 2–7.
External links
Geologic units in Iowa
{{Paleontology in the United States
Iowa
Iowa () is a state in the Midwestern region of the United States, bordered by the Mississippi River to the east and the Missouri River and Big Sioux River to the west. It is bordered by six states: Wisconsin to the northeast, Illinois to the ...
Natural history of Iowa
Science and technology in Iowa