Maastrichtian
Encyclopedia
The Maastrichtian is, in the ICS
' geologic timescale, the latest age or upper stage of the Late Cretaceous
epoch
or Upper Cretaceous series
, the Cretaceous
period or system, and of the Mesozoic
era or erathem
. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma (million years ago). The Maastrichtian was preceded by the Campanian
and succeeded by the Danian
(part of the Paleogene
and Paleocene
).
At the end of this period, there was a mass extinction commonly referred to as the Cretaceous-Tertiary extinction event
(or K/T), also now known as the Cretaceous–Paleogene (or K–Pg) extinction. At this extinction event, many commonly recognized groups such as non-avian dinosaur
s, plesiosaur
s and mosasaur
s, as well as many other lesser known groups, died out.
geologist André Hubert Dumont in 1849, after studying rock strata of the Chalk Group close to the Dutch
city of Maastricht
. These strata are now classified as the Maastricht Formation
- both formation and stage derive their names from the city. The Maastricht Formation is known for its fossils from this age, most notably those of the giant sea reptile Mosasaurus
.
The base of the Maastrichtian stage is at the first appearance of ammonite
species Pachydiscus neubergicus
. At the original type locality near Maastricht, the stratigraphic record was later found to be incomplete. A reference profile for the base was then appointed in a section along the river Ardour called Grande Carrière, close to the village of Tercis-les-Bains
in southwestern France
. The top of the Maastrichtian stage is defined to be at the iridium
anomaly at the K–T boundary
, which is also characterised by the extinction
of many groups of life, such as certain foraminifers and calcareous nannoplankton, all ammonites and belemnites, etc.
s. The biozones are (from young to old):
The Maastrichtian is roughly coeval with the Lancian
North American Land Mammal Age.
, also called the Bearpaw Shale, is a sedimentary rock
formation found in northwestern North America
. It is exposed in the U.S. state of Montana
, as well as the Canadian
provinces of Alberta
and Saskatchewan
, east of the Rocky Mountains
. It overlies the older Two Medicine
, Judith River
and Dinosaur Park Formation
s, and is in turn overlain by the Horseshoe Canyon Formation
in Canada and the Fox Hills Sandstone
in Montana. To the east and south it blends into the Pierre Shale
.
A marine
formation composed mostly of shale
, it represents the last major expansion of the Western Interior Seaway
before it completely receded from northwestern North America by the end of the Cretaceous Period. It is famous for its well-preserved ammonite
fossil
s. Other fossils found in this formation include many types of shellfish
, bony fish, shark
s, rays
, bird
s, and marine reptiles like mosasaur
s, plesiosaur
s and sea turtle
s. The occasional dinosaur
remains have also been discovered, presumably from carcasses washed out to sea.
The Hell Creek Formation
is an intensely-studied division of Upper Cretaceous to lower Paleocene
rocks in North America, named for exposures studied along Hell Creek, near Jordan, Montana
. The Hell Creek Formation occurs in badlands of eastern Montana
and portions of North Dakota
, South Dakota
, and Wyoming
. In Montana, the Hell Creek Formation overlies the Fox Hills Formation
and is the uppermost formation of the Cretaceous period.
It is a series of fresh and brackish-water clays, mudstone
s, and sandstones deposited during the Maastrichtian, the last part of the Cretaceous period, by fluvial
activity in fluctuating river channels and deltas and very occasional peaty swamp deposits along the low-lying eastern continental margin
fronting the late Cretaceous Western Interior Seaway
. The climate was mild. The famous iridium
-enriched K–T boundary
, which separates the Cretaceous from the Cenozoic
, occurs as a discontinuous but distinct thin marker bedding within the Formation, near its uppermost strata.
The Horseshoe Canyon Formation
is part of the Edmonton Series and is up to 230 m in depth. It is Late Campanian to Early Maastrichtian in age (Edmontonian Land Mammal Age) and is composed of mudstone
, sandstone
, and carbonaceous
shale
s. There are a variety of environments, which have yielded a diversity of fossil material. The Horseshoe Canyon Formation outcrops extensively in the area of Drumheller, Alberta, as well as further north along the Red Deer River near Trochu, and also in the city of Edmonton.
was discovered in southern Cyrenaica
during 1961 and is considered to be the largest oil field
in Libya
, with estimated oil reserves of 12 Goilbbl. Sarir is operated by the Arabian Gulf Oil Company
(AGOCO), a subsidiary of the state-owned National Oil Corporation
(NOC).
The Sarir stratigraphic column generally resembles succession patterns throughout the Sirte Basin, with some variations. In the early regressive phase, basal sandstones were deposited on a Precambrian
basement of igneous and metamorphic
rocks. Sandstones are dated on angiosperm pollen
as younger than Albian
, probably from the Late Cretaceous. After a lengthy hiatus, represented by unconformity and sandstone erosion, a transgressive sequence of red, green, and purple Anhydrite
shales was laid. Variegated bed remnants occur in crestal sections of many northern structures, such as in wells B-1-65 and C-1-80.
Above the transgressive sequence are Late Cretaceous shales with tight, micritic carbonate, marking the top of the Mesozoic
. These shales thicken into troughs, providing the field's sole source rock
. The youngest fauna
are Maastrichtian, with an apparent disconformity between the Late Cretaceous and Paleocene
, marked by high levels of gamma radiation on logs.
The Berivotra Formation
is an Upper Cretaceous (Maastrichtian) sedimentary rock marine formation found in Madagascar, that is contemporary to the terrestrial Maevarano Formation
.
The Maevarano Formation is an Upper Cretaceous sedimentary rock formation found in the Mahajanga Province
of northwestern Madagascar
. It is most likely Maastrichtian in age, and records a seasonal, semiarid environment with river
s that had greatly varying discharges
. Notable animal fossil
s recovered include the theropod dinosaur
Majungasaurus
and the early bird
s Rahonavis
and Vorona
, and the titanosaur
ian sauropod Rapetosaurus
.
is a sedimentary rock formation found in Madhya Pradesh
, Gujarat, and Maharashtra
, India
. It is of Maastrichtian age (Upper Cretaceous), and is notable for its dinosaur
fossil
s. Many dubious
names have been created for isolated bones, but several genera
of dinosaurs from these rocks are well-supported, including the titanosaur
sauropod Isisaurus
and the abelisaur
s Indosaurus
, Indosuchus
, Laevisuchus
, and Rajasaurus
.
, dating from the Late Cretaceous
Period, is located within and is widely represented in the Gobi Desert
basin, in the Ömnögovi Province
of Mongolia
.
It was previously known as the "Lower Nemegt Beds", occurring beneath the Nemegt Formation
and above the Djadokhta Formation. It is approximately 4 inches (101.6 mm) in thickness and was laid down roughly 80-71 mya, making it uncertain whether it should be classed as Campanian
or Maastrichtian, although the latter is less likely. The Barun Goyot Formation preserves an environment of sand dunes
, created from wind-eroded rocks (aeolian dunes).
The Nemegt Formation is a Late Cretaceous
sedimentary
formation in the Gobi Desert
of Mongolia
. It overlies, and in some places interdigitates with, the Barun Goyot Formation
. It consists of river channel sediments and contains fossil
s of fish
, turtle
s, crocodilians, bird
s and a diverse fauna
of dinosaur
s. The climate
was wetter than when the preceding formations were deposited; there seems to have existed at least some degree of forest cover.
The absolute age of the Nemegt Formation is unknown but it is thought to be Maastrichtian or maybe late Campanian
in age, very roughly some 76-65 million years old. The presence of Saurolophus
, a taxon also known from the Horseshoe Canyon Formation
of Alberta
, may indicate an Early Maastrichtian age, about 70 million years old.
. For example, Vegavis iaai indicates that at least four lineages of Anseriformes
were distinct: Anhimidae, Anatidae
, Anseranatidae
and Presbyornithidae
(and possibly Dromornithidae
), and that there was at least one Galliformes
lineage too, and apparently the Gastornithiformes
were also distinct. It is also highly likely that there was at least one, and probably several, lineages of Charadriiformes
, that penguin
s were about to split from their closest relatives or had already done so, and that if the Metaves are a valid group they would presumably have been distinct too. Also, paleognaths were of course long distinct from neognaths.
.; 2001: Numerical age calibration of the Campanian-Maastrichtian succession at Tercis-les-Bains (Landes, France) and in the Bottaccione Gorge (Italy), in: (ed.): Characterisation and correlation from Tercis-les-Bains (Landes, SW France) to Europe and other continents, IUGS Special Publication (Monograph) Series 36; Developments in Palaeontology and Stratigraphy 19, Elsevier, p. 775-782.; 2001: The global Campanian-Maastrichtian stage boundary, Episodes 24(4), pp 229–238.; 2004: Dinosaur distribution, in: (eds.): The Dinosauria, University of California Press, Berkeley (2nd ed.), ISBN 0-520-24209-2, pp 517–606.
International Commission on Stratigraphy
The International Commission on Stratigraphy , sometimes referred to by the unofficial "International Stratigraphic Commission" is a daughter or major subcommittee grade scientific daughter organization that concerns itself with stratigraphy, geological, and geochronological matters on a global...
' geologic timescale, the latest age or upper stage 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...
epoch
Epoch (geology)
An epoch is a subdivision of the geologic timescale based on rock layering. In order, the higher subdivisions are periods, eras and eons. We are currently living in the Holocene epoch...
or Upper Cretaceous series
Series (stratigraphy)
Series are subdivisions of rock layers made based on the age of the rock and corresponding to the dating system unit called an epoch, both being formally defined international conventions of the geological timescale. A series is therefore a sequence of rock depositions defining a...
, 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...
period or system, and of the Mesozoic
Mesozoic
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...
era or erathem
Erathem
In stratigraphy, paleontology, geology, and geobiology an erathem is the total stratigraphic record deposited during a certain corresponding span of time, an era in the geologic timescale....
. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma (million years ago). The Maastrichtian was preceded by the 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 ...
and succeeded by the Danian
Danian
The Danian is the oldest age or lowermost stage of the Paleocene epoch or series, the Paleogene period or system and the Cenozoic era or erathem. The beginning of the Danian age is at the Cretaceous-Tertiary extinction event...
(part of the Paleogene
Paleogene
The Paleogene is a geologic period and system that began 65.5 ± 0.3 and ended 23.03 ± 0.05 million years ago and comprises the first part of the Cenozoic Era...
and Paleocene
Paleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...
).
At the end of this period, there was a mass extinction commonly referred to as the Cretaceous-Tertiary extinction event
Cretaceous-Tertiary extinction event
The Cretaceous–Paleogene extinction event, formerly named and still commonly referred to as the Cretaceous-Tertiary extinction event, occurred approximately 65.5 million years ago at the end of the Maastrichtian age of the Cretaceous period. It was a large-scale mass extinction of animal and plant...
(or K/T), also now known as the Cretaceous–Paleogene (or K–Pg) extinction. At this extinction event, many commonly recognized groups such as non-avian dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
s, plesiosaur
Plesiosaur
Plesiosauroidea is an extinct clade of carnivorous plesiosaur marine reptiles. Plesiosauroids, are known from the Jurassic and Cretaceous Periods...
s and 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, as well as many other lesser known groups, died out.
Definition
The Maastrichtian was introduced into scientific literature by BelgianBelgium
Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...
geologist André Hubert Dumont in 1849, after studying rock strata of the Chalk Group close to the Dutch
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...
city of Maastricht
Maastricht
Maastricht is situated on both sides of the Meuse river in the south-eastern part of the Netherlands, on the Belgian border and near the German border...
. These strata are now classified as the Maastricht Formation
Maastricht Formation
The Maastricht Formation , named after the city of Maastricht, the Netherlands, is a geological formation in the Netherlands and Belgium whose strata date back to the Late Cretaceous, within 500k years of the K-Pg boundary, dated to 65.5 million years ago. The formation is part of the Chalk Group...
- both formation and stage derive their names from the city. The Maastricht Formation is known for its fossils from this age, most notably those of the giant sea reptile Mosasaurus
Mosasaurus
Mosasaurus is a genus of mosasaur, carnivorous, aquatic lizards, somewhat resembling flippered crocodiles, with elongated heavy jaws. The genus existed during the Maastrichtian age of the Cretaceous period , around 70-65 millions years ago in the area of modern Western Europe and North America...
.
The base of the Maastrichtian stage is at the first appearance of 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...
species Pachydiscus neubergicus
Pachydiscus
Pachydiscus is an extinct ammonite genus from the Upper Cretaceous with a world-wide distribution, and type for the desmoceratacean family Pachydiscidae. Its type is P. neubergicus. Altogether some 28 species have been described....
. At the original type locality near Maastricht, the stratigraphic record was later found to be incomplete. A reference profile for the base was then appointed in a section along the river Ardour called Grande Carrière, close to the village of Tercis-les-Bains
Tercis-les-Bains
Tercis-les-Bains is a commune in the Landes department in Aquitaine in south-western France.-See also:*Communes of the Landes department...
in southwestern France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
. The top of the Maastrichtian stage is defined to be at the iridium
Iridium
Iridium is the chemical element with atomic number 77, and is represented by the symbol Ir. A very hard, brittle, silvery-white transition metal of the platinum family, iridium is the second-densest element and is the most corrosion-resistant metal, even at temperatures as high as 2000 °C...
anomaly at the K–T boundary
K–T boundary
The K–T boundary is a geological signature, usually a thin band, dated to 65.5 ± 0.3 Ma ago. K is the traditional abbreviation for the Cretaceous period, and T is the abbreviation for the Tertiary period...
, which is also characterised by the extinction
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
of many groups of life, such as certain foraminifers and calcareous nannoplankton, all ammonites and belemnites, etc.
Subdivision
The Maastrichtian is commonly subdivided into two substages (Upper and Lower) and three ammonite biozoneBiozone
Biostratigraphic units or Biozones are intervals of geological strata that are defined on the basis of their characteristic fossil taxa....
s. The biozones are (from young to old):
- zone of Anapachydiscus terminusAnapachydiscusAnapachydiscus is an extinct cephalopod genus from the Upper Cretaceous, Coniacian - Maastrichtian of Europe, Africa, Madagascar, S.India, N Z, Calif. Mexico, Argentina, and the antarctic belonging to the ammonoid family Pachydiscidae....
- zone of Anapachydiscus fresvillensis
- zone of Pachydiscus neubergicusPachydiscusPachydiscus is an extinct ammonite genus from the Upper Cretaceous with a world-wide distribution, and type for the desmoceratacean family Pachydiscidae. Its type is P. neubergicus. Altogether some 28 species have been described....
till Pachydiscus epiplectus
The Maastrichtian is roughly coeval with the Lancian
Lancian
-Geology:Terrestrial sedimentary strata from the Judithian to the Lancian are generally regressive through-out the entire sequence, so the preserved changes in fossil communities represent not only phylogenetic changes but ecological zones from the submontane habitats to near-sea level coastal...
North American Land Mammal Age.
Lithostratigraphy and palaeogeography
The following are summaries of the characteristics of specific Maastrichtian aged formations.North America
The Bearpaw FormationBearpaw Formation
The Bearpaw Formation, also called the Bearpaw Shale, is a sedimentary rock formation found in northwestern North America. It is exposed in the U.S. state of Montana, as well as the Canadian provinces of Alberta and Saskatchewan, east of the Rocky Mountains...
, also called the Bearpaw Shale, is a sedimentary rock
Sedimentary rock
Sedimentary rock are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....
formation found in northwestern North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. It is exposed in the U.S. state of Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
, as well as the Canadian
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
provinces of Alberta
Alberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...
and Saskatchewan
Saskatchewan
Saskatchewan is a prairie province in Canada, which has an area of . Saskatchewan is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, and on the south by the U.S. states of Montana and North Dakota....
, east of the Rocky Mountains
Rocky Mountains
The Rocky Mountains are a major mountain range in western North America. The Rocky Mountains stretch more than from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States...
. It overlies the older Two Medicine
Two Medicine Formation
The Two Medicine Formation is a geologic formation, or rock body, that was deposited between 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma , during Campanian time, and is located in northwestern Montana...
, Judith River
Judith River Formation
The Judith River Formation is a fossil-bearing geologic formation in Montana, and is part of the Judith River Group. It dates to the upper Cretaceous, between 80 and 75 million years ago, corresponding to the "Judithian" land vertebrate age...
and Dinosaur Park Formation
Dinosaur Park Formation
The Dinosaur Park Formation is the uppermost member of the Judith River Group, a major geologic unit in southern Alberta. It was laid down over a period of time between about 76.5 and 75 million years ago. The formation is made up of deposits of a high-sinuosity fluvial system, and is capped...
s, and is in turn overlain by the Horseshoe Canyon Formation
Horseshoe Canyon Formation
The Horseshoe Canyon Formation is part of the Edmonton Group and is up to 230m in thickness. It is Late Campanian to Early Maastrichtian in age and is composed of mudstone, sandstone, and carbonaceous shales...
in Canada and the Fox Hills Sandstone
Fox Hills Formation
The Fox Hills Formation is a Cretaceous geologic formation in the northwestern Great Plains of North America. It is present from Alberta on the north to Colorado in the south....
in Montana. To the east and south it blends into 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 marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
formation composed mostly of 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...
, it represents the last major expansion of 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...
before it completely receded from northwestern North America by the end of the Cretaceous Period. It is famous for its well-preserved 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...
fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s. Other fossils found in this formation include many types of shellfish
Shellfish
Shellfish is a culinary and fisheries term for exoskeleton-bearing aquatic invertebrates used as food, including various species of molluscs, crustaceans, and echinoderms. Although most kinds of shellfish are harvested from saltwater environments, some kinds are found only in freshwater...
, bony fish, 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, rays
Batoidea
Batoidea is a superorder of cartilaginous fish commonly known as rays and skates, containing more than 500 described species in thirteen families...
, 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, and marine reptiles like 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, plesiosaur
Plesiosaur
Plesiosauroidea is an extinct clade of carnivorous plesiosaur marine reptiles. Plesiosauroids, are known from the Jurassic and Cretaceous Periods...
s and sea turtle
Sea turtle
Sea turtles are marine reptiles that inhabit all of the world's oceans except the Arctic.-Distribution:...
s. The occasional dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
remains have also been discovered, presumably from carcasses washed out to sea.
Hell Creek Formation
The Hell Creek Formation is an intensely-studied division of Upper Cretaceous to lower Paleocene rocks in North America, named for exposures studied along Hell Creek, near Jordan, Montana...
is an intensely-studied division of Upper Cretaceous to lower Paleocene
Paleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...
rocks in North America, named for exposures studied along Hell Creek, near Jordan, Montana
Jordan, Montana
Jordan is a town in and the county seat of Garfield County, Montana, United States. The population was 364 at the 2000 census.-History:Originally settled in 1896, Jordan received a post office on July 11, 1899...
. The Hell Creek Formation occurs in badlands of eastern Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
and portions of North Dakota
North Dakota
North Dakota is a state located in the Midwestern region of the United States of America, along the Canadian border. The state is bordered by Canada to the north, Minnesota to the east, South Dakota to the south and Montana to the west. North Dakota is the 19th-largest state by area in the U.S....
, South Dakota
South Dakota
South Dakota is a state located in the Midwestern region of the United States. It is named after the Lakota and Dakota Sioux American Indian tribes. Once a part of Dakota Territory, South Dakota became a state on November 2, 1889. The state has an area of and an estimated population of just over...
, and Wyoming
Wyoming
Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High...
. In Montana, the Hell Creek Formation overlies the Fox Hills Formation
Fox Hills Formation
The Fox Hills Formation is a Cretaceous geologic formation in the northwestern Great Plains of North America. It is present from Alberta on the north to Colorado in the south....
and is the uppermost formation of the Cretaceous period.
It is a series of fresh and brackish-water clays, mudstone
Mudstone
Mudstone is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the...
s, and sandstones deposited during the Maastrichtian, the last part of the Cretaceous period, by fluvial
Fluvial
Fluvial is used in geography and Earth science to refer to the processes associated with rivers and streams and the deposits and landforms created by them...
activity in fluctuating river channels and deltas and very occasional peaty swamp deposits along the low-lying eastern continental margin
Continental margin
The continental margin is the zone of the ocean floor that separates the thin oceanic crust from thick continental crust. Continental margins constitute about 28% of the oceanic area....
fronting the late Cretaceous 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...
. The climate was mild. The famous iridium
Iridium
Iridium is the chemical element with atomic number 77, and is represented by the symbol Ir. A very hard, brittle, silvery-white transition metal of the platinum family, iridium is the second-densest element and is the most corrosion-resistant metal, even at temperatures as high as 2000 °C...
-enriched K–T boundary
K–T boundary
The K–T boundary is a geological signature, usually a thin band, dated to 65.5 ± 0.3 Ma ago. K is the traditional abbreviation for the Cretaceous period, and T is the abbreviation for the Tertiary period...
, which separates the Cretaceous from the Cenozoic
Cenozoic
The Cenozoic era is the current and most recent of the three Phanerozoic geological eras and covers the period from 65.5 mya to the present. The era began in the wake of the Cretaceous–Tertiary extinction event at the end of the Cretaceous that saw the demise of the last non-avian dinosaurs and...
, occurs as a discontinuous but distinct thin marker bedding within the Formation, near its uppermost strata.
The Horseshoe Canyon Formation
Horseshoe Canyon Formation
The Horseshoe Canyon Formation is part of the Edmonton Group and is up to 230m in thickness. It is Late Campanian to Early Maastrichtian in age and is composed of mudstone, sandstone, and carbonaceous shales...
is part of the Edmonton Series and is up to 230 m in depth. It is Late Campanian to Early Maastrichtian in age (Edmontonian Land Mammal Age) and is composed of mudstone
Mudstone
Mudstone is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the...
, sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
, and carbonaceous
Carbonaceous
Carbonaceous is the defining attribute of a substance rich in carbon. Particularly, carbonaceous hydrocarbons are very unsaturated, high-molecular-weight hydrocarbons, having an elevated carbon:hydrogen ratio....
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...
s. There are a variety of environments, which have yielded a diversity of fossil material. The Horseshoe Canyon Formation outcrops extensively in the area of Drumheller, Alberta, as well as further north along the Red Deer River near Trochu, and also in the city of Edmonton.
Africa
The Sarir FieldSarir field
The Sarir Field was discovered in southern Cyrenaica during 1961 and is considered to be the largest oil field in Libya, with estimated oil reserves of...
was discovered in southern Cyrenaica
Cyrenaica
Cyrenaica is the eastern coastal region of Libya.Also known as Pentapolis in antiquity, it was part of the Creta et Cyrenaica province during the Roman period, later divided in Libia Pentapolis and Libia Sicca...
during 1961 and is considered to be the largest oil field
Oil field
An oil field is a region with an abundance of oil wells extracting petroleum from below ground. Because the oil reservoirs typically extend over a large area, possibly several hundred kilometres across, full exploitation entails multiple wells scattered across the area...
in Libya
Libya
Libya is an African country in the Maghreb region of North Africa bordered by the Mediterranean Sea to the north, Egypt to the east, Sudan to the southeast, Chad and Niger to the south, and Algeria and Tunisia to the west....
, with estimated oil reserves of 12 Goilbbl. Sarir is operated by the Arabian Gulf Oil Company
Arabian Gulf Oil Company
The Arabian Gulf Oil Company is an oil company based in Benghazi, Libya, engaged in crude oil and natural gas exploration, production and refining. It was a subsidiary of the state-owned National Oil Corporation . -Overview:...
(AGOCO), a subsidiary of the state-owned National Oil Corporation
National Oil Corporation
The National Oil Corporation is the national oil company of Libya. It dominates Libya's oil industry, along with a number of smaller subsidiaries, which combined account for around 70% the country's oil output...
(NOC).
The Sarir stratigraphic column generally resembles succession patterns throughout the Sirte Basin, with some variations. In the early regressive phase, basal sandstones were deposited on a Precambrian
Precambrian
The Precambrian is the name which describes the large span of time in Earth's history before the current Phanerozoic Eon, and is a Supereon divided into several eons of the geologic time scale...
basement of igneous and metamorphic
Metamorphic rock
Metamorphic rock is the transformation of an existing rock type, the protolith, in a process called metamorphism, which means "change in form". The protolith is subjected to heat and pressure causing profound physical and/or chemical change...
rocks. Sandstones are dated on angiosperm pollen
Pollen
Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...
as younger than Albian
Albian
The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous epoch/series. Its approximate time range is 112.0 ± 1.0 Ma to 99.6 ± 0.9 Ma...
, probably from the Late Cretaceous. After a lengthy hiatus, represented by unconformity and sandstone erosion, a transgressive sequence of red, green, and purple Anhydrite
Anhydrite
Anhydrite is a mineral – anhydrous calcium sulfate, CaSO4. It is in the orthorhombic crystal system, with three directions of perfect cleavage parallel to the three planes of symmetry. It is not isomorphous with the orthorhombic barium and strontium sulfates, as might be expected from the...
shales was laid. Variegated bed remnants occur in crestal sections of many northern structures, such as in wells B-1-65 and C-1-80.
Above the transgressive sequence are Late Cretaceous shales with tight, micritic carbonate, marking the top of the Mesozoic
Mesozoic
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...
. These shales thicken into troughs, providing the field's sole source rock
Source rock
In petroleum geology, source rock refers to rocks from which hydrocarbons have been generated or are capable of being generated. They form one of the necessary elements of a working petroleum system. They are organic-rich sediments that may have been deposited in a variety of environments including...
. The youngest fauna
Fauna
Fauna or faunæ is all of the animal life of any particular region or time. The corresponding term for plants is flora.Zoologists and paleontologists use fauna to refer to a typical collection of animals found in a specific time or place, e.g. the "Sonoran Desert fauna" or the "Burgess shale fauna"...
are Maastrichtian, with an apparent disconformity between the Late Cretaceous and Paleocene
Paleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...
, marked by high levels of gamma radiation on logs.
The Berivotra Formation
Berivotra Formation
The Berivotra Formation is an Upper Cretaceous sedimentary rock marine formation found in Madagascar, that is contemporary to the terrestrial Maevarano Formation....
is an Upper Cretaceous (Maastrichtian) sedimentary rock marine formation found in Madagascar, that is contemporary to the terrestrial Maevarano Formation
Maevarano Formation
The Maevarano Formation is an Upper Cretaceous sedimentary rock formation found in the Mahajanga Province of northwestern Madagascar. It is most likely Maastrichtian in age, and records a seasonal, semiarid environment with rivers that had greatly varying discharges...
.
The Maevarano Formation is an Upper Cretaceous sedimentary rock formation found in the Mahajanga Province
Mahajanga Province
Mahajanga is a former province of Madagascar with an area of 150,023 km². It had a population of 1,896,000 . Its capital was Mahajanga.Except for Fianarantsoa, Mahajanga Province bordered all of the country's other provinces:...
of northwestern Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
. It is most likely Maastrichtian in age, and records a seasonal, semiarid environment with river
River
A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...
s that had greatly varying discharges
Discharge (hydrology)
In hydrology, discharge is the volume rate of water flow, including any suspended solids , dissolved chemical species and/or biologic material , which is transported through a given cross-sectional area...
. Notable animal fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s recovered include the theropod dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
Majungasaurus
Majungasaurus
Majungasaurus is a genus of abelisaurid theropod dinosaur that lived in Madagascar from 70 to 65.5 million years ago, at the end of the Cretaceous Period. Only one species has been identified...
and the early 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 Rahonavis
Rahonavis
Rahonavis is a genus of bird-like dinosaur from the Late Cretaceous of what is now northwestern Madagascar. It is known from a partial skeleton found in Maevarano Formation rocks at a quarry near Berivotra, Mahajanga Province...
and Vorona
Vorona
Vorona is a monotypic genus of prehistoric birds. It was described from fossils found in a Maevarano Formation quarry near the village of Berivotra, Mahajanga Province, Madagascar. The age is Late Cretaceous, probably Campanian . V...
, and the titanosaur
Titanosaur
Titanosaurs were a diverse group of sauropod dinosaurs, which included Saltasaurus and Isisaurus. It includes some of the heaviest creatures ever to walk the earth, such as Argentinosaurus and Paralititan — which some believe have weighed up to 100 tonnes...
ian sauropod Rapetosaurus
Rapetosaurus
Rapetosaurus is a genus of sauropod dinosaur that lived in Madagascar from 70 to 65 million years ago, at the end of the Cretaceous Period. Only one species Rapetosaurus is a genus of sauropod dinosaur that lived in Madagascar from 70 to 65 million years ago, at the end of the Cretaceous Period....
.
India
The Lameta FormationLameta Formation
The Lameta Formation is a sedimentary rock formation found in Madhya Pradesh, Gujarat, and Maharashtra, India. It is of Maastrichtian age , and is notable for its dinosaur fossils...
is a sedimentary rock formation found in Madhya Pradesh
Madhya Pradesh
Madhya Pradesh , often called the Heart of India, is a state in central India. Its capital is Bhopal and Indore is the largest city....
, Gujarat, and Maharashtra
Maharashtra
Maharashtra is a state located in India. It is the second most populous after Uttar Pradesh and third largest state by area in India...
, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
. It is of Maastrichtian age (Upper Cretaceous), and is notable for its dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s. Many dubious
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
names have been created for isolated bones, but several genera
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of dinosaurs from these rocks are well-supported, including the titanosaur
Titanosaur
Titanosaurs were a diverse group of sauropod dinosaurs, which included Saltasaurus and Isisaurus. It includes some of the heaviest creatures ever to walk the earth, such as Argentinosaurus and Paralititan — which some believe have weighed up to 100 tonnes...
sauropod Isisaurus
Isisaurus
Isisaurus is a genus of dinosaur from the Late Cretaceous Period. Isisaurus was a sauropod , which lived in what is now India....
and the abelisaur
Abelisaur
Abelisaurs were a group of ceratosaurian dinosaurs which lived in the Southern hemisphere during the Cretaceous period. Some well-known dinosaurs of this group include Abelisaurus, Carnotaurus, and Majungasaurus. They are known for their small arms...
s Indosaurus
Indosaurus
Indosaurus is a genus of theropod dinosaur once living in what is now India. It lived approximately 69 million years ago, in the Maastrichtian division of the Late Cretaceous...
, Indosuchus
Indosuchus
Indosuchus is a genus of abelisaurid dinosaur from the Late Cretaceous Period , a theropod related to Abelisaurus. Like most theropods, Indosuchus was a bipedal carnivore...
, Laevisuchus
Laevisuchus
Laevisuchus is a genus of abelisauroid theropod dinosaur from the Late Cretaceous.Its remains were discovered by Charles Alfred Matley near Jabalpur in Maastrichtian deposits in the Lameta Formation in India, and named and described by paleontologists Friedrich von Huene and Matley in 1933. The...
, and Rajasaurus
Rajasaurus
Rajasaurus is a genus of carnivorous abelisaurian theropod dinosaur with an unusual head crest. Between 1982 and 1984, its fossilized bones were discovered by Suresh Srivastava of the Geological Survey of India...
.
Asia
The Barun Goyot FormationBarun Goyot Formation
The Barun Goyot Formation , dating from the Late Cretaceous Period, is located within and is widely represented in the Gobi Desert basin, in the Ömnögovi Province of Mongolia....
, dating from the Late 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...
Period, is located within and is widely represented in the Gobi Desert
Gobi Desert
The Gobi is a large desert region in Asia. It covers parts of northern and northwestern China, and of southern Mongolia. The desert basins of the Gobi are bounded by the Altai Mountains and the grasslands and steppes of Mongolia on the north, by the Hexi Corridor and Tibetan Plateau to the...
basin, in the Ömnögovi Province
Ömnögovi Province
Ömnögovi is an aimag of Mongolia, located in the south of the country, in the Gobi Desert. Ömnögovi is Mongolia's largest aimag. The capital is Dalanzadgad....
of Mongolia
Mongolia
Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...
.
It was previously known as the "Lower Nemegt Beds", occurring beneath the Nemegt Formation
Nemegt Formation
The Nemegt Formation is a geological formation dating from the Late Cretaceous sedimentary from the Gobi Desert of Mongolia. It overlies and sometimes forms folds with the Barun Goyot Formation. It consists of river channel sediments and contains fossils of fish, turtles, crocodilians, birds and a...
and above the Djadokhta Formation. It is approximately 4 inches (101.6 mm) in thickness and was laid down roughly 80-71 mya, making it uncertain whether it should be classed as 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 ...
or Maastrichtian, although the latter is less likely. The Barun Goyot Formation preserves an environment of sand dunes
Dune
In physical geography, a dune is a hill of sand built by wind. Dunes occur in different forms and sizes, formed by interaction with the wind. Most kinds of dunes are longer on the windward side where the sand is pushed up the dune and have a shorter "slip face" in the lee of the wind...
, created from wind-eroded rocks (aeolian dunes).
The Nemegt Formation is a Late 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...
sedimentary
Sedimentary rock
Sedimentary rock are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....
formation in the Gobi Desert
Gobi Desert
The Gobi is a large desert region in Asia. It covers parts of northern and northwestern China, and of southern Mongolia. The desert basins of the Gobi are bounded by the Altai Mountains and the grasslands and steppes of Mongolia on the north, by the Hexi Corridor and Tibetan Plateau to the...
of Mongolia
Mongolia
Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...
. It overlies, and in some places interdigitates with, the Barun Goyot Formation
Barun Goyot Formation
The Barun Goyot Formation , dating from the Late Cretaceous Period, is located within and is widely represented in the Gobi Desert basin, in the Ömnögovi Province of Mongolia....
. It consists of river channel sediments and contains fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s of fish
Fish
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...
, turtle
Turtle
Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield...
s, crocodilians, 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 and a diverse fauna
Fauna
Fauna or faunæ is all of the animal life of any particular region or time. The corresponding term for plants is flora.Zoologists and paleontologists use fauna to refer to a typical collection of animals found in a specific time or place, e.g. the "Sonoran Desert fauna" or the "Burgess shale fauna"...
of dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
s. The climate
Climate
Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and other meteorological elemental measurements in a given region over long periods...
was wetter than when the preceding formations were deposited; there seems to have existed at least some degree of forest cover.
The absolute age of the Nemegt Formation is unknown but it is thought to be Maastrichtian or maybe late 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 ...
in age, very roughly some 76-65 million years old. The presence of Saurolophus
Saurolophus
Saurolophus is a genus of large hadrosaurine duckbill that lived about 69.5-68.5 million years ago, in the Late Cretaceous of North America and Asia; it is one of the few genera of dinosaurs known from multiple continents. It is distinguished by a spike-like crest which projects up and back...
, a taxon also known from the Horseshoe Canyon Formation
Horseshoe Canyon Formation
The Horseshoe Canyon Formation is part of the Edmonton Group and is up to 230m in thickness. It is Late Campanian to Early Maastrichtian in age and is composed of mudstone, sandstone, and carbonaceous shales...
of Alberta
Alberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...
, may indicate an Early Maastrichtian age, about 70 million years old.
Paleontology
Birds
Several lineages of modern birds existed, though many were of lineages that differed profoundly from their relatives of today and thus are not their ancestors, but became extinct in the CenozoicCenozoic
The Cenozoic era is the current and most recent of the three Phanerozoic geological eras and covers the period from 65.5 mya to the present. The era began in the wake of the Cretaceous–Tertiary extinction event at the end of the Cretaceous that saw the demise of the last non-avian dinosaurs and...
. For example, Vegavis iaai indicates that at least four lineages of Anseriformes
Anseriformes
The order Anseriformes contains about 150 living species of birds in three extant families: the Anhimidae , Anseranatidae , and the Anatidae, which includes over 140 species of waterfowl, among them the ducks, geese, and swans.All species in the order are highly adapted for an aquatic existence at...
were distinct: Anhimidae, Anatidae
Anatidae
Anatidae is the biological family of birds that includes ducks, geese and swans. The family has a cosmopolitan distribution, occurring on all the world's continents except Antarctica and on most of the world's islands and island groups...
, Anseranatidae
Anseranatidae
Anseranatidae, the magpie-geese, is a biological family of waterbirds. It is a unique member of the order Anseriformes. The only living species, the Magpie Goose, is a resident breeder in northern Australia and in southern New Guinea....
and Presbyornithidae
Presbyornithidae
Presbyornithidae were a family of waterbirds with an apparently global distribution that lived until the Earliest Oligocene, but are now extinct...
(and possibly Dromornithidae
Dromornithidae
Dromornithidae — the dromornithids — were a family of large, flightless Australian birds of the Oligocene through Pleistocene epochs. All are now extinct. They were long classified in the order Struthioniformes, but are now usually classified as a family of Anseriformes1...
), and that there was at least one Galliformes
Galliformes
Galliformes are an order of heavy-bodied ground-feeding domestic or game bird, containing turkey, grouse, chicken, New and Old World Quail, ptarmigan, partridge, pheasant, and the Cracidae. Common names are gamefowl or gamebirds, landfowl, gallinaceous birds or galliforms...
lineage too, and apparently the Gastornithiformes
Gastornithiformes
Gastornithiformes are an order of prehistoric birds. The birds from this group lived from the Paleocene to the Eocene and were spread out across Asia, Europe, and North America. All the birds were very large birds that were flightless, similar to an ostrich but more heavily built and with a huge...
were also distinct. It is also highly likely that there was at least one, and probably several, lineages of Charadriiformes
Charadriiformes
Charadriiformes is a diverse order of small to medium-large birds. It includes about 350 species and has members in all parts of the world. Most Charadriiformes live near water and eat invertebrates or other small animals; however, some are pelagic , some occupy deserts and a few are found in thick...
, that penguin
Penguin
Penguins are a group of aquatic, flightless birds living almost exclusively in the southern hemisphere, especially in Antarctica. Highly adapted for life in the water, penguins have countershaded dark and white plumage, and their wings have become flippers...
s were about to split from their closest relatives or had already done so, and that if the Metaves are a valid group they would presumably have been distinct too. Also, paleognaths were of course long distinct from neognaths.
Literature
; 2004: A Geologic Time Scale 2004, Cambridge University PressCambridge University Press
Cambridge University Press is the publishing business of the University of Cambridge. Granted letters patent by Henry VIII in 1534, it is the world's oldest publishing house, and the second largest university press in the world...
.; 2001: Numerical age calibration of the Campanian-Maastrichtian succession at Tercis-les-Bains (Landes, France) and in the Bottaccione Gorge (Italy), in: (ed.): Characterisation and correlation from Tercis-les-Bains (Landes, SW France) to Europe and other continents, IUGS Special Publication (Monograph) Series 36; Developments in Palaeontology and Stratigraphy 19, Elsevier, p. 775-782.; 2001: The global Campanian-Maastrichtian stage boundary, Episodes 24(4), pp 229–238.; 2004: Dinosaur distribution, in: (eds.): The Dinosauria, University of California Press, Berkeley (2nd ed.), ISBN 0-520-24209-2, pp 517–606.
External links
- GeoWhen Database - Maastrichtian
- Late Cretaceous timescale, at the website of the subcommission for stratigraphic information of the ICS
- Stratigraphic chart of the Late Cretaceous, at the website of Norges Network of offshore records of geology and stratigraphy
- Maastrichtian Microfossils: 60+ images of Foraminifera