Niobrara Formation
Encyclopedia
The Niobrara Formation, also called the Niobrara Chalk , is a geologic formation in North America that was laid down between 87 and 82 million years ago during the Coniacian
, Santonian
, and Campanian
ages of the Late Cretaceous
. It is composed of two structural units, the Smoky Hill Chalk Member
overlying the Fort Hays Limestone Member. The chalk formed from the accumulation of coccoliths from microorganisms living in what was once the Western Interior Seaway
, an inland sea that divided the continent of North America during much of the Cretaceous
. It underlies much of the Great Plains of the US and Canada. Evidence of vertebrate life is common throughout the formation and includes specimens of plesiosaur
s, mosasaur
s, and pterosaurs as well as several primitive aquatic bird
s. The type locality
for the Niobrara Chalk is Knox County
in northeastern Nebraska
.
of Yale University
in 1870. This and following expeditions to the area in 1871 and 1872 yielded the first of many fossil vertebrate remains commonly attributed with the formation. Excavations continued through the following years up to 1879 under the direction of professional fossil collectors such as B. F. Mudge
and S. W. Williston
appointed by Marsh.
The Niobrara Chalk has been continuously explored ever since, with specimens being found by H. T. Martin of the University of Kansas
and George F. Sternberg
, the son of the famous fossil collector Charles H. Sternberg. Much of the best material from the formation is on display at the Sternberg Museum of Natural History in Hays
, Kansas
.
of the Niobrara Chalk was fully understood. Specimens were described as being from layers referred to as being either of gray-blue shale
or yellow chalk
. This dichotomy
is not indicative of different stratigraphic units as was previously thought, but rather is seen as a weathering phenomenon that can be found at varying points in the same outcrop.
The Niobrara Formation is overlain by the marine Pierre Shale
.
. Life of the Niobrara Chalk is comparable to that of the Dakota Formation
, although the Dakota Formation, which was deposited during the Cenomanian
, predates the chalk by about 10 million years.
s, oyster
s, crinoid
s, ammonite
s, and squid
are all common in the Niobrara Chalk and must have comprised the majority of life at the time. Evidence of sponges, annelid worms
, and crustacean
s are less common and are usually found as trace fossil
s.
are by far the most common fossils found from the formation, with remains of pehistoric shark
s, ray-finned fishes
, and lobe-finned fishes
in abundance. As well as smaller fish, many large predatory fish were present in the seas at that time, most notably Xiphactinus
. Several fish were of close relation to modern day fish including primitive coelocanths, slime heads, lancetfish
, gars
, swordfish
, and salmonids
.
s have been found from the Niobrara Chalk that reached large sizes. The biggest, Archelon
, attained a length of up to 4m, and was about 4.87m from flipper to flipper, considerably larger than its distant relative, the leatherback sea turtle
, which is the largest of the sea turtles alive today. The sea turtles most likely fed on ammonites, squid, and other cephalopod
s.
oidea in the Niobrara Chalk: the Polycotylidae
, or short-necked plesiosaurs, and the Elasmosauridae
, or long-necked plesiosaurs. Polycotylids superficially resemble pliosaur
s, which are not present within the formation, but are unrelated. They were fast swimmers, unlike the Elasmosaurs that used their long necks to catch fish. Plesiosaurs are rare in the formation and were therefore likely uncommon in the seas at the time. Specimens become much more numerous in the Pierre Shale
situated above the chalk.
Mosasaurs are the most common marine reptiles in the Niobrara Chalk and the most successful ones in the sea at the time. Four different genre representing the four different subfamilies of Mosasaur
idae: the Tylosaurinae
, Plioplatecarpinae
, Mosasaurinae
, and Halisaurinae
, were present in Niobrara. They were the dominant carnivorous marine reptiles and ate cephalopods, fish, turtles, pterosaurs, birds, and even plesiosaurs.. There is evidence of them consuming other smaller mosasaurs. Despite this, mosasaurs often fell prey to some of the large sharks at the time, such as Cretoxyrhina.
The presence of young mosasaurs in the formation suggests that mosasaurs were viviparous
and gave birth hundreds of miles out to sea, as Niobrara was in the middle of the Western Interior Seaway at the time. Juveniles would have been vulnerable to predation by the many large mid-ocean predators, so it is likely that mosasaurs lived in groups rather than solitarily. Also, viviparous species tend to have much fewer offspring than egg-laying ones, so if there were few young that were born, they were most likely to have sought protection withinin groups in order to reach adulthood and thereby maintain the population of mosasaurs.
belong to the Pteranodontidae
family of the suborder Pterodactyloidea
, though even Nyctosaurus has occasionally been included in that family, and is at least a close relative of the pteranodonts. All are large pterosaurs with elongated cranial crests in male specimens. The pterosaurs of Niobrara probably spent most of their time at sea and rarely went on land. Landing on all four limbs would have required these long-winged pterosaurs to fold their wings back, thus reducing lift and making it a very difficult and improbable way of landing safely. Nyctosaurus lacked all but the fourth phalanx
of the hand, which is the extended finger that supports the wing membrane, meaning that quadrupedal locomotion on the ground would have been limited compared to other pterosaurs that were proficient at walking based on fossilized trackways
that show both limbs in use on the ground.
Nonavian dinosaurs have been found in the Niobrara Chalk despite it being located hundreds of miles out to sea at the time. The most reasonable theory is that the carcasses drifted out to sea. It is unlikely that the bodies were carried out by outgoing tides along the shorelines where they died, but rather it is more probable that the dinosaurs were carried offshore by floodwaters during a storm. In the shallow waters the bodies would have began to decompose
and bacteria within the carcass would have produced gasses that would have accumulated in the gut, thereby making the body buoyant
. Next, the prevailing winds and currents would have carried it out to sea, where it would eventually settle to the bottom and be buried in sediment.
A few caudal vertebrae from a hadrosaur
have been found with bite marks and have been eroded, suggesting at one point they were digested. A single tooth belonging to Squalicorax
was found in situ
under the vertebrae. This suggested the shark consumed the posterior end of the tail of a floating hadrosaur carcass and had partially digested it before fossilization. Most dinosaurs in the chalk were nodosaurs
. No remains of cerapods
nor non-avian theropods
were found, both being common dinosaurs present at the time.
s are present in the formation, although rare. Both were unrelated to modern birds, as they still retained teeth. Baptornis
and Hesperornis
were large flightless aquatic birds suited for diving. Ichthyornis
was a seabird that resembled the gull
s and petrel
s of today. Both probably preyed on small fish and were preyed upon by sharks, large bony fish such as Xiphactinus
, and mosasaurs.
{| class="wikitable" align="center" width="100%"
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! colspan="5" align="center" |Bird
s of the Niobrara Chalk
|-
! Taxa
! Presence
! Description
! Images
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Genus:
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| A baptornithid hesperornithiform
about 1m long.
| rowspan="99" |
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Genus:
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| A large hesperornithid hesperornithiform
about 2m in length.
|-
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Genus:
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| An ichthyornithid about 60 cm long.
|-
|}
is produced from the Niobrara in the eastern Denver Basin
. Oil is produced from the Niobrara in the North Park Basin
and new fracturing methods are allowing much larger areas to be tapped for oil.
The Fort Hays member is mined for the manufacture of Portland cement
at Superior, Nebraska
and Lyons, Colorado
, and was formerly used for that purpose in Ellis County, Kansas
.
Coniacian
The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous epoch or Upper Cretaceous series and spans the time between 89.3 ± 1 Ma and 85.8 ± 0.7 Ma...
, Santonian
Santonian
The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous epoch or Upper Cretaceous series. It spans the time between 85.8 ± 0.7 mya and 83.5 ± 0.7 mya...
, and Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...
ages of the Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
. It is composed of two structural units, the Smoky Hill Chalk Member
Smoky Hill Chalk
The Smoky Hill Chalk Member of the Niobrara Chalk formation is a Cretaceous conservation Lagerstätte, or fossil rich geological formation, known primarily for its exceptionally well-preserved marine reptiles. The Smoky Hill Chalk Member is the uppermost of the two structural units of the Niobrara...
overlying the Fort Hays Limestone Member. The chalk formed from the accumulation of coccoliths from microorganisms living in what was once the Western Interior Seaway
Western Interior Seaway
The Western Interior Seaway, also called the Cretaceous Seaway, the Niobraran Sea, and the North American Inland Sea, was a huge inland sea that split the continent of North America into two halves, Laramidia and Appalachia, during most of the mid- and late-Cretaceous Period...
, an inland sea that divided the continent of North America during much of the Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
. It underlies much of the Great Plains of the US and Canada. Evidence of vertebrate life is common throughout the formation and includes specimens of plesiosaur
Plesiosaur
Plesiosauroidea is an extinct clade of carnivorous plesiosaur marine reptiles. Plesiosauroids, are known from the Jurassic and Cretaceous Periods...
s, mosasaur
Mosasaur
Mosasaurs are large extinct marine lizards. The first fossil remains were discovered in a limestone quarry at Maastricht on the Meuse in 1764...
s, and pterosaurs as well as several primitive aquatic bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s. The type locality
Type locality (geology)
Type locality , also called type area or type locale, is the where a particular rock type, stratigraphic unit, fossil or mineral species is first identified....
for the Niobrara Chalk is Knox County
Knox County, Nebraska
-History:The Lewis and Clark Expedition passed through the area on 4 September 1804.The US Treaty with the Ponca tribe was signed at White Paint Creek on 9 June 1825.Knox County was formed in 1854. It was named after Major General Henry Knox.-Demographics:...
in northeastern Nebraska
Nebraska
Nebraska is a state on the Great Plains of the Midwestern United States. The state's capital is Lincoln and its largest city is Omaha, on the Missouri River....
.
History of Exploration
The Niobrara Chalk was first studied during an expedition led by Othniel Charles MarshOthniel Charles Marsh
Othniel Charles Marsh was an American paleontologist. Marsh was one of the preeminent scientists in the field; the discovery or description of dozens of news species and theories on the origins of birds are among his legacies.Born into a modest family, Marsh was able to afford higher education...
of Yale University
Yale University
Yale University is a private, Ivy League university located in New Haven, Connecticut, United States. Founded in 1701 in the Colony of Connecticut, the university is the third-oldest institution of higher education in the United States...
in 1870. This and following expeditions to the area in 1871 and 1872 yielded the first of many fossil vertebrate remains commonly attributed with the formation. Excavations continued through the following years up to 1879 under the direction of professional fossil collectors such as B. F. Mudge
Benjamin Franklin Mudge
Benjamin Franklin Mudge was an American lawyer, geologist and teacher. Briefly the mayor of Lynn, Massachusetts, he later moved to Kansas where he was appointed the first State Geologist. He led the first geological survey of the state in 1864, and published the first book on the geology of Kansas...
and S. W. Williston
Samuel Wendell Williston
Samuel Wendell Williston was an American educator and paleontologist who was the first to propose that birds developed flight cursorially , rather than arboreally . He was also an entomologist, specialising in Diptera.-Early life:Williston was born in Boston, Massachusetts to Samuel Williston and...
appointed by Marsh.
The Niobrara Chalk has been continuously explored ever since, with specimens being found by H. T. Martin of the University of Kansas
University of Kansas
The University of Kansas is a public research university and the largest university in the state of Kansas. KU campuses are located in Lawrence, Wichita, Overland Park, and Kansas City, Kansas with the main campus being located in Lawrence on Mount Oread, the highest point in Lawrence. The...
and George F. Sternberg
George F. Sternberg
George Fryer Sternberg was a paleontologist best known for his discovery in Gove County, Kansas of the "fish-within-a-fish" of Xiphactinus audax. He was the son of Charles Hazelius Sternberg and nephew of Brig. Gen. George M. Sternberg...
, the son of the famous fossil collector Charles H. Sternberg. Much of the best material from the formation is on display at the Sternberg Museum of Natural History in Hays
Hays
- Places :Australia* Hays Reef, TasmaniaCanada* Hays, AlbertaUnited States* Hays, Kansas** Fort Hays** Hays Regional Airport* Hays, Montana* Hays, North Carolina* Hays, Texas* Hays , a neighborhood in Pittsburgh, Pennsylvania...
, Kansas
Kansas
Kansas is a US state located in the Midwestern United States. It is named after the Kansas River which flows through it, which in turn was named after the Kansa Native American tribe, which inhabited the area. The tribe's name is often said to mean "people of the wind" or "people of the south...
.
Stratigraphy
The Smoky Hill Member of the Niobrara Chalk contains the majority of the fossils found in the formation, and is subdivided into 23 marker beds. Most vertebrates are present from the upper half of the member. Most of the vertebrate remains were collected and described before the stratigraphyStratigraphy
Stratigraphy, a branch of geology, studies rock layers and layering . It is primarily used in the study of sedimentary and layered volcanic rocks....
of the Niobrara Chalk was fully understood. Specimens were described as being from layers referred to as being either of gray-blue shale
Shale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
or yellow chalk
Chalk
Chalk is a soft, white, porous sedimentary rock, a form of limestone composed of the mineral calcite. Calcite is calcium carbonate or CaCO3. It forms under reasonably deep marine conditions from the gradual accumulation of minute calcite plates shed from micro-organisms called coccolithophores....
. This dichotomy
Dichotomy
A dichotomy is any splitting of a whole into exactly two non-overlapping parts, meaning it is a procedure in which a whole is divided into two parts...
is not indicative of different stratigraphic units as was previously thought, but rather is seen as a weathering phenomenon that can be found at varying points in the same outcrop.
The Niobrara Formation is overlain by the marine Pierre Shale
Pierre Shale
The Pierre Shale is a geologic formation or series in the Upper Cretaceous which occurs east of the Rocky Mountains in the Great Plains, from North Dakota to New Mexico....
.
Flora and fauna
During the time of the deposition of the Niobrara Chalk, much life inhabited the seas of the Western Interior Seaway. By this time in the Late Cretaceous many new lifeforms appeared such as mosasaurs, which were to be the some of the last of the aquatic lifeforms to evolve before the end of the MesozoicMesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
. Life of the Niobrara Chalk is comparable to that of the Dakota Formation
Dakota Formation
The Dakota Formation is a geologic formation composed of sedimentary rocks deposited on the western side of the Late Cretaceous Western Interior Seaway. F.B. Meek and F.V. Hayden named it for exposures along the Missouri River near Dakota City, Nebraska...
, although the Dakota Formation, which was deposited during the Cenomanian
Cenomanian
The Cenomanian is, in the ICS' geological timescale the oldest or earliest age of the Late Cretaceous epoch or the lowest stage of the Upper Cretaceous series. An age is a unit of geochronology: it is a unit of time; the stage is a unit in the stratigraphic column deposited during the corresponding...
, predates the chalk by about 10 million years.
Invertebrate Life
ClamClam
The word "clam" can be applied to freshwater mussels, and other freshwater bivalves, as well as marine bivalves.In the United States, "clam" can be used in several different ways: one, as a general term covering all bivalve molluscs...
s, oyster
Oyster
The word oyster is used as a common name for a number of distinct groups of bivalve molluscs which live in marine or brackish habitats. The valves are highly calcified....
s, crinoid
Crinoid
Crinoids are marine animals that make up the class Crinoidea of the echinoderms . Crinoidea comes from the Greek word krinon, "a lily", and eidos, "form". They live both in shallow water and in depths as great as 6,000 meters. Sea lilies refer to the crinoids which, in their adult form, are...
s, ammonite
Ammonite
Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct subclass within the Molluscan class Cephalopoda which are more closely related to living coleoids Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct...
s, and squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
are all common in the Niobrara Chalk and must have comprised the majority of life at the time. Evidence of sponges, annelid worms
Annelid
The annelids , formally called Annelida , are a large phylum of segmented worms, with over 17,000 modern species including ragworms, earthworms and leeches...
, and crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s are less common and are usually found as trace fossil
Trace fossil
Trace fossils, also called ichnofossils , are geological records of biological activity. Trace fossils may be impressions made on the substrate by an organism: for example, burrows, borings , urolites , footprints and feeding marks, and root cavities...
s.
Fish
FishFish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate 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...
are by far the most common fossils found from the formation, with remains of pehistoric shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....
s, ray-finned fishes
Actinopterygii
The Actinopterygii or ray-finned fishes constitute a class or sub-class of the bony fishes.The ray-finned fishes are so called because they possess lepidotrichia or "fin rays", their fins being webs of skin supported by bony or horny spines , as opposed to the fleshy, lobed fins that characterize...
, and lobe-finned fishes
Sarcopterygii
The Sarcopterygii or lobe-finned fishes – sometimes considered synonymous with Crossopterygii constitute a clade of the bony fishes, though a strict classification would include the terrestrial vertebrates...
in abundance. As well as smaller fish, many large predatory fish were present in the seas at that time, most notably Xiphactinus
Xiphactinus
Xiphactinus was a large, 4.5 to 6 m long predatory bony fish that lived in the Western Interior Sea, over what is now the middle of North America, during the Late Cretaceous. When alive, the fish would have resembled a gargantuan, fanged tarpon...
. Several fish were of close relation to modern day fish including primitive coelocanths, slime heads, lancetfish
Alepisauriformes
Alepisauriformes is an order of fish described by Regan in 1911. The only living genus of this order is Alepisaurus . A Russian fossil of Apateodus dates back around 112 million years....
, gars
Lepisosteus
Lepisosteus is a genus of gars in the family Lepisosteidae.There are four species:* Lepisosteus oculatus Winchell, 1864 * Lepisosteus osseus...
, swordfish
Swordfish
Swordfish , also known as broadbill in some countries, are large, highly migratory, predatory fish characterized by a long, flat bill. They are a popular sport fish of the billfish category, though elusive. Swordfish are elongated, round-bodied, and lose all teeth and scales by adulthood...
, and salmonids
Salmonidae
Salmonidae is a family of ray-finned fish, the only living family currently placed in the order Salmoniformes. It includes salmon, trout, chars, freshwater whitefishes and graylings...
.
| Cartilaginous Fish Chondrichthyes Chondrichthyes or cartilaginous fishes are jawed fish with paired fins, paired nares, scales, two-chambered hearts, and skeletons made of cartilage rather than bone... of the Niobrara Chalk |
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Genus:
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A large lamniform Lamniformes Lamniformes is an order of sharks commonly known as mackerel sharks . It includes some of the most familiar species of sharks, such as the great white shark, as well as more unusual representatives, such as the goblin shark and the megamouth shark.Members of the order are distinguished by... shark about 7m long. |
 |
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Genus:
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A lamniform Lamniformes Lamniformes is an order of sharks commonly known as mackerel sharks . It includes some of the most familiar species of sharks, such as the great white shark, as well as more unusual representatives, such as the goblin shark and the megamouth shark.Members of the order are distinguished by... shark smaller than Cretoxyrhina. |
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Genus:
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An odontaspidid lamniform Lamniformes Lamniformes is an order of sharks commonly known as mackerel sharks . It includes some of the most familiar species of sharks, such as the great white shark, as well as more unusual representatives, such as the goblin shark and the megamouth shark.Members of the order are distinguished by... shark. |
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Genus:
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A lamniform Lamniformes Lamniformes is an order of sharks commonly known as mackerel sharks . It includes some of the most familiar species of sharks, such as the great white shark, as well as more unusual representatives, such as the goblin shark and the megamouth shark.Members of the order are distinguished by... shark about 5m long. |
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Genus:
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A mitsukurinid Mitsukurinidae Mitsukurinidae, also called goblin sharks is a family of sharks with one living genus, Mitsukurina, and three extinct genera: Anomotodon, Pseudoscapanorhynchus and Scapanorhynchus, though some taxonomists consider Scapanorhynchus to be a synonym of Mitsukurina... shark similar in appearance to the modern day goblin shark Goblin shark The goblin shark, Mitsukurina owstoni, is a deep-sea shark, the sole living species in the family Mitsukurinidae. The most distinctive characteristic of the goblin shark is the unusual shape of its head. It has a long, trowel-shaped, beak-like rostrum or snout, much longer than other sharks' snouts... . |
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A ptychodontid Ptychodontidae Ptychodontidae is a family of extinct hybodontiform sharks which lived from the Cretaceous to the Paleogene.... hybodontoid shark. |
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Genus:
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A callorhinchid chimaeriform related to the modern ratfish. | |||
| Bony Fish Osteichthyes Osteichthyes , also called bony fish, are a taxonomic group of fish that have bony, as opposed to cartilaginous, skeletons. The vast majority of fish are osteichthyes, which is an extremely diverse and abundant group consisting of over 29,000 species... of the Niobrara Chalk |
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A pycnodontiform Pycnodontiformes Pycnodontiformes is an extinct order of bony fish. The group evolved during the Late Triassic and disappeared during the Eocene. The group has been found in rock formations in Africa, Asia, Europe, North and South America.... fish similar but unrelated to modern parrotfish Parrotfish Parrotfishes are a group of fishes that traditionally had been considered a family , but now often are considered a subfamily of the wrasses. They are found in relatively shallow tropical and subtropical oceans throughout the world, but with the largest species richness in the Indo-Pacific... . |
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Genus:
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A lepisosteid gar. | |||
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Genus:
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A primitive swordfish Swordfish Swordfish , also known as broadbill in some countries, are large, highly migratory, predatory fish characterized by a long, flat bill. They are a popular sport fish of the billfish category, though elusive. Swordfish are elongated, round-bodied, and lose all teeth and scales by adulthood... about 3m in length. |
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A large ichthyodectid Ichthyodectidae The family Ichthyodectidae was a family of marine actinopterygian fish. Sometimes classified in the primitive bony fish order Pachycormiformes, they are today generally regarded as members of the "bulldog fish" order Ichthyodectiformes in the far more advanced Osteoglossomorpha... pachycormiform Pachycormiformes Pachycormiformes is an extinct order of ray-finned fish known from Mesozoic deposits from Eurasia and the Americas. They were characterized by having serrated pectoral fins, reduced pelvic fins and a bony rostrum... about 5m in length. |
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An ichthyodectid Ichthyodectidae The family Ichthyodectidae was a family of marine actinopterygian fish. Sometimes classified in the primitive bony fish order Pachycormiformes, they are today generally regarded as members of the "bulldog fish" order Ichthyodectiformes in the far more advanced Osteoglossomorpha... pachycormiform Pachycormiformes Pachycormiformes is an extinct order of ray-finned fish known from Mesozoic deposits from Eurasia and the Americas. They were characterized by having serrated pectoral fins, reduced pelvic fins and a bony rostrum... about 2m in length. |
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An ichthyodectid Ichthyodectidae The family Ichthyodectidae was a family of marine actinopterygian fish. Sometimes classified in the primitive bony fish order Pachycormiformes, they are today generally regarded as members of the "bulldog fish" order Ichthyodectiformes in the far more advanced Osteoglossomorpha... pachycormiform Pachycormiformes Pachycormiformes is an extinct order of ray-finned fish known from Mesozoic deposits from Eurasia and the Americas. They were characterized by having serrated pectoral fins, reduced pelvic fins and a bony rostrum... about 2m in length. |
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A saurodontine ichthyodectid Ichthyodectidae The family Ichthyodectidae was a family of marine actinopterygian fish. Sometimes classified in the primitive bony fish order Pachycormiformes, they are today generally regarded as members of the "bulldog fish" order Ichthyodectiformes in the far more advanced Osteoglossomorpha... pachycormiform Pachycormiformes Pachycormiformes is an extinct order of ray-finned fish known from Mesozoic deposits from Eurasia and the Americas. They were characterized by having serrated pectoral fins, reduced pelvic fins and a bony rostrum... |
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Genus:
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A saurodontine ichthyodectid Ichthyodectidae The family Ichthyodectidae was a family of marine actinopterygian fish. Sometimes classified in the primitive bony fish order Pachycormiformes, they are today generally regarded as members of the "bulldog fish" order Ichthyodectiformes in the far more advanced Osteoglossomorpha... pachycormiform Pachycormiformes Pachycormiformes is an extinct order of ray-finned fish known from Mesozoic deposits from Eurasia and the Americas. They were characterized by having serrated pectoral fins, reduced pelvic fins and a bony rostrum... |
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A bananogmiid albuliform elopiform Elopiformes Elopiformes is the order of ray-finned fish that includes the tarpons, tenpounders, and ladyfish, as well as a number of extinct types. They have a long fossil record, easily distinguished from other fishes by the presence of an additional set of bones in the throat.They are related to the order... |
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A tselfatiiform. | |||
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Genus:
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A crossognathiform. | |||
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Genus:
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A crossognathiform. | |||
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Genus:
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A crossognathiform. | |||
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Genus:
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A crossognathiform. | |||
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Genus:
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A crossognathiform about 12 cm in length. | |||
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A ferrifronsid acanthomorph Acanthomorpha Acanthomorpha is an order of prehistoric fish that was described by Rosen in 1973. Fossils range from the Late Cretaceous to the Early Oligocene -28.4mya)... . |
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An actinopterygian Actinopterygii The Actinopterygii or ray-finned fishes constitute a class or sub-class of the bony fishes.The ray-finned fishes are so called because they possess lepidotrichia or "fin rays", their fins being webs of skin supported by bony or horny spines , as opposed to the fleshy, lobed fins that characterize... of indeterminant classification |
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A cimolichthyid salmoniform protacanthopterygii Protacanthopterygii Protacanthopterygii is a ray-finned fish taxon ranked as a superorder of the infraclass Teleostei. They inhabit both marine and freshwater habitat... an. |
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An enchodontid salmoniform protacanthopterygii Protacanthopterygii Protacanthopterygii is a ray-finned fish taxon ranked as a superorder of the infraclass Teleostei. They inhabit both marine and freshwater habitat... an. |
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An alepisauriform Alepisauriformes Alepisauriformes is an order of fish described by Regan in 1911. The only living genus of this order is Alepisaurus . A Russian fossil of Apateodus dates back around 112 million years.... actinopterygii Actinopterygii The Actinopterygii or ray-finned fishes constitute a class or sub-class of the bony fishes.The ray-finned fishes are so called because they possess lepidotrichia or "fin rays", their fins being webs of skin supported by bony or horny spines , as opposed to the fleshy, lobed fins that characterize... an related to the modern lancetfish Lancetfish Lancetfishes are large oceanic predatory fishes in the genus Alepisaurus , the only living genus in the family Alepisauridae.... and lizardfish Synodontidae The Lizardfishes are a family, the Synodontidae, of aulopiform fish. They are found in tropical and subtropical marine waters throughout the world.... . |
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An alepisauriform Alepisauriformes Alepisauriformes is an order of fish described by Regan in 1911. The only living genus of this order is Alepisaurus . A Russian fossil of Apateodus dates back around 112 million years.... actinopterygii Actinopterygii The Actinopterygii or ray-finned fishes constitute a class or sub-class of the bony fishes.The ray-finned fishes are so called because they possess lepidotrichia or "fin rays", their fins being webs of skin supported by bony or horny spines , as opposed to the fleshy, lobed fins that characterize... an. |
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An alepisauriform Alepisauriformes Alepisauriformes is an order of fish described by Regan in 1911. The only living genus of this order is Alepisaurus . A Russian fossil of Apateodus dates back around 112 million years.... actinopterygii Actinopterygii The Actinopterygii or ray-finned fishes constitute a class or sub-class of the bony fishes.The ray-finned fishes are so called because they possess lepidotrichia or "fin rays", their fins being webs of skin supported by bony or horny spines , as opposed to the fleshy, lobed fins that characterize... an. |
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A beryciform Beryciformes Beryciformes is an order of ray-finned fishes. This is a very poorly understood group of 16 families, 57 genera, and about 219 species. Some people believe that it is probably an artificial assemblage of unrelated taxa that are thrown together for convenience only; there are no convincing... actinopterygii Actinopterygii The Actinopterygii or ray-finned fishes constitute a class or sub-class of the bony fishes.The ray-finned fishes are so called because they possess lepidotrichia or "fin rays", their fins being webs of skin supported by bony or horny spines , as opposed to the fleshy, lobed fins that characterize... an. |
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A beryciform Beryciformes Beryciformes is an order of ray-finned fishes. This is a very poorly understood group of 16 families, 57 genera, and about 219 species. Some people believe that it is probably an artificial assemblage of unrelated taxa that are thrown together for convenience only; there are no convincing... actinopterygii Actinopterygii The Actinopterygii or ray-finned fishes constitute a class or sub-class of the bony fishes.The ray-finned fishes are so called because they possess lepidotrichia or "fin rays", their fins being webs of skin supported by bony or horny spines , as opposed to the fleshy, lobed fins that characterize... an. |
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A polymixiid Beardfish The beardfishes are a small family of deep-sea marine ray-finned fish named for their pair of long hyoid barbels. They have little economic importance.... actinopterygii Actinopterygii The Actinopterygii or ray-finned fishes constitute a class or sub-class of the bony fishes.The ray-finned fishes are so called because they possess lepidotrichia or "fin rays", their fins being webs of skin supported by bony or horny spines , as opposed to the fleshy, lobed fins that characterize... an closely related to the modern Beardfish Beardfish The beardfishes are a small family of deep-sea marine ray-finned fish named for their pair of long hyoid barbels. They have little economic importance.... |
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Turtles
Sea turtleSea turtle
Sea turtles are marine reptiles that inhabit all of the world's oceans except the Arctic.-Distribution:...
s have been found from the Niobrara Chalk that reached large sizes. The biggest, Archelon
Archelon
Archelon is a genus of extinct sea turtle, the largest that has ever been documented.-Discovery:...
, attained a length of up to 4m, and was about 4.87m from flipper to flipper, considerably larger than its distant relative, the leatherback sea turtle
Leatherback Sea Turtle
The leatherback sea turtle is the largest of all living sea turtles and the fourth largest modern reptile behind three crocodilians. It is the only living species in the genus Dermochelys. It can easily be differentiated from other modern sea turtles by its lack of a bony shell. Instead, its...
, which is the largest of the sea turtles alive today. The sea turtles most likely fed on ammonites, squid, and other cephalopod
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...
s.
| Sea turtle Sea turtle Sea turtles are marine reptiles that inhabit all of the world's oceans except the Arctic.-Distribution:... s of the Niobrara Chalk |
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A toxichelid cryptodire Cryptodira Cryptodira is the taxonomic suborder of Testudines that includes most living tortoises and turtles. Cryptodira differ from Pleurodira in that they lower their necks and pull the heads straight back into the shells; instead of folding their necks sideways along the body under the shells' margins... . |
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A chelonioid cryptodire Cryptodira Cryptodira is the taxonomic suborder of Testudines that includes most living tortoises and turtles. Cryptodira differ from Pleurodira in that they lower their necks and pull the heads straight back into the shells; instead of folding their necks sideways along the body under the shells' margins... about 2m long. |
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A protostegid Protostegidae Protostegidae is a family of extinct marine turtles that lived during the Mesozoic Era. The family includes some of the largest sea turtles that ever existed. The largest, Archelon, had a head a meter long... cryptodire Cryptodira Cryptodira is the taxonomic suborder of Testudines that includes most living tortoises and turtles. Cryptodira differ from Pleurodira in that they lower their necks and pull the heads straight back into the shells; instead of folding their necks sideways along the body under the shells' margins... about 3m long. |
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A large protostegid Protostegidae Protostegidae is a family of extinct marine turtles that lived during the Mesozoic Era. The family includes some of the largest sea turtles that ever existed. The largest, Archelon, had a head a meter long... cryptodire Cryptodira Cryptodira is the taxonomic suborder of Testudines that includes most living tortoises and turtles. Cryptodira differ from Pleurodira in that they lower their necks and pull the heads straight back into the shells; instead of folding their necks sideways along the body under the shells' margins... about 4m long. |
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Plesiosaurs
Plesiosaurs are present from two different families within PlesiosaurPlesiosaur
Plesiosauroidea is an extinct clade of carnivorous plesiosaur marine reptiles. Plesiosauroids, are known from the Jurassic and Cretaceous Periods...
oidea in the Niobrara Chalk: the Polycotylidae
Polycotylidae
Polycotylidae is a family of plesiosaurs from the Cretaceous, a sister group to the Leptocleididae.With their short necks and large elongated heads, they resemble the pliosaurs, but closer phylogenetical studies indicate that they share many common features with the plesiosauridae and elasmosauridae...
, or short-necked plesiosaurs, and the Elasmosauridae
Elasmosauridae
Elasmosauridae was the family of plesiosaurs. They had the longest necks of the plesiosaurs and survived from the Late Triassic to the end of the Cretaceous. They had a diet of fish and shelless cephalopods.-Size:...
, or long-necked plesiosaurs. Polycotylids superficially resemble pliosaur
Pliosaur
Pliosauroidea is an extinct clade of marine reptiles. Pliosauroids, also commonly known as pliosaurs, are known from the Jurassic and Cretaceous Periods. The pliosauroids were short-necked plesiosaurs with large heads and massive toothed jaws. These swimming reptiles were not dinosaurs but distant...
s, which are not present within the formation, but are unrelated. They were fast swimmers, unlike the Elasmosaurs that used their long necks to catch fish. Plesiosaurs are rare in the formation and were therefore likely uncommon in the seas at the time. Specimens become much more numerous in the Pierre Shale
Pierre Shale
The Pierre Shale is a geologic formation or series in the Upper Cretaceous which occurs east of the Rocky Mountains in the Great Plains, from North Dakota to New Mexico....
situated above the chalk.
| Plesiosaur Plesiosaur Plesiosauroidea is an extinct clade of carnivorous plesiosaur marine reptiles. Plesiosauroids, are known from the Jurassic and Cretaceous Periods... s of the Niobrara Chalk |
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A polycotylid Polycotylidae Polycotylidae is a family of plesiosaurs from the Cretaceous, a sister group to the Leptocleididae.With their short necks and large elongated heads, they resemble the pliosaurs, but closer phylogenetical studies indicate that they share many common features with the plesiosauridae and elasmosauridae... . |
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Genus:
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A polycotylid Polycotylidae Polycotylidae is a family of plesiosaurs from the Cretaceous, a sister group to the Leptocleididae.With their short necks and large elongated heads, they resemble the pliosaurs, but closer phylogenetical studies indicate that they share many common features with the plesiosauridae and elasmosauridae... about 3m in length. |
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A large elasmosaurid Elasmosauridae Elasmosauridae was the family of plesiosaurs. They had the longest necks of the plesiosaurs and survived from the Late Triassic to the end of the Cretaceous. They had a diet of fish and shelless cephalopods.-Size:... about 12m in length. |
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A large elasmosaurid Elasmosauridae Elasmosauridae was the family of plesiosaurs. They had the longest necks of the plesiosaurs and survived from the Late Triassic to the end of the Cretaceous. They had a diet of fish and shelless cephalopods.-Size:... about 14m in length. |
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Mosasaurs
Mosasaur
Mosasaurs are large extinct marine lizards. The first fossil remains were discovered in a limestone quarry at Maastricht on the Meuse in 1764...
idae: the Tylosaurinae
Tylosaurinae
Tylosaurinae is a subfamily of mosasaurs, a diverse group of Late Cretaceous marine lizards.Russell defined the Tylosaurinae as follows: "Large rostrum present anterior to premaxillary teeth. Twelve or more teeth in dentary and maxilla. Cranial nerves X, XI, and XII leave lateral wall of...
, Plioplatecarpinae
Plioplatecarpinae
Plioplatecarpinae is a subfamily of mosasaurs, a diverse group of late Cretaceous marine squamates.Russell defined the Plioplatecarpinae as follows: Small rostrum present or absent anterior to premaxillary teeth. Cranial nerves X, XI, XII leave lateral wall of opisthotic through single foramen...
, Mosasaurinae
Mosasaurinae
Mosasaurinae is a subfamily of mosasaurs, a diverse group of Late Cretaceous marine squamates.Russell defined the Mosasurinae as differing from all other mosasaurs as follows: "Small rostrum present or absent anterior to premaxillary teeth. Fourteen or more teeth present in dentary and maxilla...
, and Halisaurinae
Halisaurinae
Halisaurinae is a subfamily of mosasaurs, a diverse group of Late Cretaceous marine squamates.Bardet et al. diagnosed the Halsaurinae as all mosasaurs more closely related to Halisaurus than Moanasaurus...
, were present in Niobrara. They were the dominant carnivorous marine reptiles and ate cephalopods, fish, turtles, pterosaurs, birds, and even plesiosaurs.. There is evidence of them consuming other smaller mosasaurs. Despite this, mosasaurs often fell prey to some of the large sharks at the time, such as Cretoxyrhina.
Vivipary
Vivipary has two different meanings. In animals, it means development of the embryo inside the body of the mother, eventually leading to live birth, as opposed to laying eggs...
and gave birth hundreds of miles out to sea, as Niobrara was in the middle of the Western Interior Seaway at the time. Juveniles would have been vulnerable to predation by the many large mid-ocean predators, so it is likely that mosasaurs lived in groups rather than solitarily. Also, viviparous species tend to have much fewer offspring than egg-laying ones, so if there were few young that were born, they were most likely to have sought protection withinin groups in order to reach adulthood and thereby maintain the population of mosasaurs.
| Mosasaur Mosasaur Mosasaurs are large extinct marine lizards. The first fossil remains were discovered in a limestone quarry at Maastricht on the Meuse in 1764... s of the Niobrara Chalk |
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A large tylosaurine Tylosaurinae Tylosaurinae is a subfamily of mosasaurs, a diverse group of Late Cretaceous marine lizards.Russell defined the Tylosaurinae as follows: "Large rostrum present anterior to premaxillary teeth. Twelve or more teeth in dentary and maxilla. Cranial nerves X, XI, and XII leave lateral wall of... about 15m long. |
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Genus:
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A plioplatecarpine Plioplatecarpinae Plioplatecarpinae is a subfamily of mosasaurs, a diverse group of late Cretaceous marine squamates.Russell defined the Plioplatecarpinae as follows: Small rostrum present or absent anterior to premaxillary teeth. Cranial nerves X, XI, XII leave lateral wall of opisthotic through single foramen... about 4.3m long. |
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Genus:
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A small mosasaurine Mosasaurinae Mosasaurinae is a subfamily of mosasaurs, a diverse group of Late Cretaceous marine squamates.Russell defined the Mosasurinae as differing from all other mosasaurs as follows: "Small rostrum present or absent anterior to premaxillary teeth. Fourteen or more teeth present in dentary and maxilla... about 4m long. |
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Genus:
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A small halisaurine Halisaurinae Halisaurinae is a subfamily of mosasaurs, a diverse group of Late Cretaceous marine squamates.Bardet et al. diagnosed the Halsaurinae as all mosasaurs more closely related to Halisaurus than Moanasaurus... only 2.5m long. |
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Pterosaurs
Between two and four genera of pterosaurs are present in the formation, depending on the taxonomy. All but NyctosaurusNyctosaurus
Nyctosaurus is a genus of pterodactyloid pterosaur, the remains of which have been found in the Niobrara Formation of the mid-western United States, which, during the late Cretaceous Period, was covered in an extensive shallow sea. The genus Nyctosaurus has had numerous species referred to it,...
belong to the Pteranodontidae
Pteranodontidae
The Pteranodontidae are a family of large pterosaurs of the Cretaceous Period of North America.The family was named in 1876 by Othniel Charles Marsh....
family of the suborder Pterodactyloidea
Pterodactyloidea
Pterodactyloidea forms one of the two suborders of pterosaurs , and contains the most derived members of this group of flying reptiles...
, though even Nyctosaurus has occasionally been included in that family, and is at least a close relative of the pteranodonts. All are large pterosaurs with elongated cranial crests in male specimens. The pterosaurs of Niobrara probably spent most of their time at sea and rarely went on land. Landing on all four limbs would have required these long-winged pterosaurs to fold their wings back, thus reducing lift and making it a very difficult and improbable way of landing safely. Nyctosaurus lacked all but the fourth phalanx
Phalanx bones
In anatomy, phalanx bones are those that form the fingers and toes. In primates such as humans and monkeys, the thumb and big toe have two phalanges, while the other fingers and toes consist of three. Phalanges are classified as long bones.The phalanges do not have individual names...
of the hand, which is the extended finger that supports the wing membrane, meaning that quadrupedal locomotion on the ground would have been limited compared to other pterosaurs that were proficient at walking based on fossilized trackways
Fossil trackway
A fossil trackway is a type of trace fossil, a trackway made by an organism. Many fossil trackways were made by dinosaurs, early tetrapods, and other quadrupeds and bipeds on land...
that show both limbs in use on the ground.
| Pterosaur Pterosaur Pterosaurs were flying reptiles of the clade or order Pterosauria. They existed from the late Triassic to the end of the Cretaceous Period . Pterosaurs are the earliest vertebrates known to have evolved powered flight... s of the Niobrara Chalk |
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A large pteranodontid Pteranodontidae The Pteranodontidae are a family of large pterosaurs of the Cretaceous Period of North America.The family was named in 1876 by Othniel Charles Marsh.... Ornithocheiroid. |
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Genus:
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Second possible species G. maysei present in the Pierre Shale Pierre Shale The Pierre Shale is a geologic formation or series in the Upper Cretaceous which occurs east of the Rocky Mountains in the Great Plains, from North Dakota to New Mexico.... . |
The largest pteranodontid, with a wingspan of about 9m. Often included as species of Pteranodon. | ||
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Genus:
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A nyctosaurid ornithocheiroid. Some specimens preserve an extremely elongated cranial crest. | |||
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Genus:
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Possible specimens also present in the Pierre Shale Pierre Shale The Pierre Shale is a geologic formation or series in the Upper Cretaceous which occurs east of the Rocky Mountains in the Great Plains, from North Dakota to New Mexico.... . |
A large pteranodontid. | ||
Nonavian Dinosaurs
Decomposition
Decomposition is the process by which organic material is broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death...
and bacteria within the carcass would have produced gasses that would have accumulated in the gut, thereby making the body buoyant
Buoyancy
In physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...
. Next, the prevailing winds and currents would have carried it out to sea, where it would eventually settle to the bottom and be buried in sediment.
A few caudal vertebrae from a hadrosaur
Hadrosaurid
Hadrosaurids or duck-billed dinosaurs are members of the family Hadrosauridae, and include ornithopods such as Edmontosaurus and Parasaurolophus. They were common herbivores in the Upper Cretaceous Period of what are now Asia, Europe and North America. They are descendants of the Upper...
have been found with bite marks and have been eroded, suggesting at one point they were digested. A single tooth belonging to Squalicorax
Squalicorax
Squalicorax is a genus of extinct lamniform shark known to have lived during the Cretaceous period. A fully articulated 1.9 m long fossil skeleton of Squalicorax has been found in Kansas, evidence of its presence in the Western Interior Seaway...
was found in situ
In situ
In situ is a Latin phrase which translated literally as 'In position'. It is used in many different contexts.-Aerospace:In the aerospace industry, equipment on board aircraft must be tested in situ, or in place, to confirm everything functions properly as a system. Individually, each piece may...
under the vertebrae. This suggested the shark consumed the posterior end of the tail of a floating hadrosaur carcass and had partially digested it before fossilization. Most dinosaurs in the chalk were nodosaurs
Nodosauridae
Nodosauridae is a family of ankylosaurian dinosaurs, from the Late Jurassic to the Late Cretaceous Period of what are now North America, Asia, Antarctica and Europe.-Characteristics:...
. No remains of cerapods
Cerapoda
Neornithischia is a clade of the dinosaur order Ornithischia. They are the sister group of the Thyreophora within the clade Genasauria. Neornithischians are united by having a thicker layer of asymmetrical enamel on the inside of their lower teeth...
nor non-avian theropods
Theropoda
Theropoda is both a suborder of bipedal saurischian dinosaurs, and a clade consisting of that suborder and its descendants . Dinosaurs belonging to the suborder theropoda were primarily carnivorous, although a number of theropod groups evolved herbivory, omnivory, and insectivory...
were found, both being common dinosaurs present at the time.
| Non-avian dinosaurs of the Niobrara Chalk | ||||
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A small hadrosaurid Hadrosaurid Hadrosaurids or duck-billed dinosaurs are members of the family Hadrosauridae, and include ornithopods such as Edmontosaurus and Parasaurolophus. They were common herbivores in the Upper Cretaceous Period of what are now Asia, Europe and North America. They are descendants of the Upper... about 3.5m long. |
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Genus:
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A hadrosaurid Hadrosaurid Hadrosaurids or duck-billed dinosaurs are members of the family Hadrosauridae, and include ornithopods such as Edmontosaurus and Parasaurolophus. They were common herbivores in the Upper Cretaceous Period of what are now Asia, Europe and North America. They are descendants of the Upper... of indeterminant classification about 9m in length. Possibly Corythosaurus Corythosaurus Corythosaurus is a genus of duck-billed dinosaur from the Upper Cretaceous Period, about 77-76.5 million years ago. It lived in what is now North America... . |
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Genus:
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A nodosaurid Nodosauridae Nodosauridae is a family of ankylosaurian dinosaurs, from the Late Jurassic to the Late Cretaceous Period of what are now North America, Asia, Antarctica and Europe.-Characteristics:... ankylosaur Ankylosauria Ankylosauria is a group of herbivorous dinosaurs of the order Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony osteoderms. Ankylosaurs were bulky quadrupeds, with short, powerful limbs. They are first known to have appeared in the early Jurassic Period of... . |
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Genus:
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A nodosaurid Nodosauridae Nodosauridae is a family of ankylosaurian dinosaurs, from the Late Jurassic to the Late Cretaceous Period of what are now North America, Asia, Antarctica and Europe.-Characteristics:... ankylosaur Ankylosauria Ankylosauria is a group of herbivorous dinosaurs of the order Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony osteoderms. Ankylosaurs were bulky quadrupeds, with short, powerful limbs. They are first known to have appeared in the early Jurassic Period of... . |
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Birds
Three genre of birdBird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s are present in the formation, although rare. Both were unrelated to modern birds, as they still retained teeth. Baptornis
Baptornis
Baptornis is an extinct genus of flightless aquatic bird from the Late Cretaceous, some 87-80 million years ago . The fossils of Baptornis advenus, the type species, were discovered in Kansas, which at its time was mostly covered by the Western Interior Seaway, a shallow shelf sea...
and Hesperornis
Hesperornis
Hesperornis is a genus of flightless aquatic birds that spanned the first half of the Campanian age of the Late Cretaceous period . One of the lesser-known discoveries of the paleontologist O. C. Marsh in the late 19th century Bone Wars, it was an important early find in the history of avian...
were large flightless aquatic birds suited for diving. Ichthyornis
Ichthyornis
Ichthyornis is a genus of toothed seabirds from the Late Cretaceous of North America. Its fossil remains are known from the chalks of Alberta, Alabama, Kansas, New Mexico, Saskatchewan, and Texas, in strata that were laid down in the Western Interior Seaway during the Turonian-Campanian ages,...
was a seabird that resembled the gull
Gull
Gulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...
s and petrel
Petrel
Petrels are tube-nosed seabirds in the bird order Procellariiformes. The common name does not indicate relationship beyond that point, as "petrels" occur in three of the four families within that group...
s of today. Both probably preyed on small fish and were preyed upon by sharks, large bony fish such as Xiphactinus
Xiphactinus
Xiphactinus was a large, 4.5 to 6 m long predatory bony fish that lived in the Western Interior Sea, over what is now the middle of North America, during the Late Cretaceous. When alive, the fish would have resembled a gargantuan, fanged tarpon...
, and mosasaurs.
{| class="wikitable" align="center" width="100%"
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! colspan="5" align="center" |Bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s of the Niobrara Chalk
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! Taxa
! Presence
! Description
! Images
|-
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Genus:
- BaptornisBaptornisBaptornis is an extinct genus of flightless aquatic bird from the Late Cretaceous, some 87-80 million years ago . The fossils of Baptornis advenus, the type species, were discovered in Kansas, which at its time was mostly covered by the Western Interior Seaway, a shallow shelf sea...
- B. advenus
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| A baptornithid hesperornithiform
Hesperornithiformes
Hesperornithes is an extinct and highly specialized clade of Cretaceous toothed birds. Hesperornithine birds, apparently limited to former aquatic habitats in the Northern Hemisphere, include genera such as Hesperornis, Parahesperornis, Baptornis, Enaliornis, and probably Potamornis, all...
about 1m long.
| rowspan="99" |
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Genus:
- HesperornisHesperornisHesperornis is a genus of flightless aquatic birds that spanned the first half of the Campanian age of the Late Cretaceous period . One of the lesser-known discoveries of the paleontologist O. C. Marsh in the late 19th century Bone Wars, it was an important early find in the history of avian...
- H. regalis
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| A large hesperornithid hesperornithiform
Hesperornithiformes
Hesperornithes is an extinct and highly specialized clade of Cretaceous toothed birds. Hesperornithine birds, apparently limited to former aquatic habitats in the Northern Hemisphere, include genera such as Hesperornis, Parahesperornis, Baptornis, Enaliornis, and probably Potamornis, all...
about 2m in length.
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Genus:
- IchthyornisIchthyornisIchthyornis is a genus of toothed seabirds from the Late Cretaceous of North America. Its fossil remains are known from the chalks of Alberta, Alabama, Kansas, New Mexico, Saskatchewan, and Texas, in strata that were laid down in the Western Interior Seaway during the Turonian-Campanian ages,...
- I. dispar
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| An ichthyornithid about 60 cm long.
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Mineral resources
The Niobrara is in places a commercial hydrocarbon reservoir. Natural gasNatural gas
Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...
is produced from the Niobrara in the eastern Denver Basin
Denver Basin
The Denver Basin, sometimes also called the Julesburg Basin, Denver-Julesburg Basin , or the D-J Basin, is a geologic structural basin centered in eastern Colorado in the United States, but extending into southeast Wyoming, western Nebraska, and western Kansas...
. Oil is produced from the Niobrara in the North Park Basin
North Park (Colorado basin)
North Park is a high, sparsely populated basin in the Rocky Mountains in north central Colorado in the United States. It encompasses a wide valley in Jackson County rimmed by mountain ranges at the headwaters of the North Platte River and several smaller tributaries, including the Michigan River,...
and new fracturing methods are allowing much larger areas to be tapped for oil.
The Fort Hays member is mined for the manufacture of Portland cement
Portland cement
Portland cement is the most common type of cement in general use around the world because it is a basic ingredient of concrete, mortar, stucco and most non-specialty grout...
at Superior, Nebraska
Superior, Nebraska
Superior is a city in Nuckolls County, Nebraska, United States. As of the 2010 census, the city population was 1,957.Superior bills itself as the "Victorian Capital of Nebraska", and holds an annual Victorian Festival...
and Lyons, Colorado
Lyons, Colorado
Lyons is a Statutory Town in Boulder County, Colorado, United States. The population was 1,585 at the 2000 census. Lyons is located at the confluence of the North St. Vrain Creek and the South St. Vrain Creek, twenty miles east of Rocky Mountain National Park. Due to its location at the...
, and was formerly used for that purpose in Ellis County, Kansas
Ellis County, Kansas
Ellis County is a county located in Northwest Kansas, in the Central United States. As of the 2010 census, the county population was 28,452. Its county seat and most populous city is Hays...
.
External links and references
- The Niobrara Chalk Formation at DinoData.
- Oceans of Kansas website.
Other references
- Bennett, S. C. 2000. Inferring Stratigraphic Position of Fossil Vertebrates from the Niobrara Chalk of Western Kansas. College of Chiropractic, University of Bridgeport, Bridgeport, CT 06601-2449.