Cenozoic Era ( /ˌsiːnəˈzoʊɪk, ˌsɛ-/) is the current
geological era, covering the period from 66 million years ago to the
Cenozoic is also known as the Age of Mammals, because of the large
mammals that dominate it. The continents also moved into their current
positions during this era.
3 Animal life
7 See also
10 External links
Cenozoic, meaning "new life," is derived from Greek καινός
kainós "new," and ζωή zōḗ "life." The era is also known as
the Cænozoic, Caenozoic, or Cainozoic. /ˌkaɪnəˈzoʊɪk,
Cenozoic is divided into three periods: the Paleogene, Neogene,
and Quaternary; and seven epochs: the Paleocene, Eocene, Oligocene,
Miocene, Pliocene, Pleistocene, and Holocene. The
was officially recognized by the International Commission on
Stratigraphy in June 2009, and the former term, Tertiary Period,
became officially disused in 2004 due to the need to divide the
Cenozoic into periods more like those of the earlier
Mesozoic eras.[why?] The common use of epochs during the Cenozoic
helps paleontologists better organize and group the many significant
events that occurred during this comparatively short interval of time.
Knowledge of this era is relatively more detailed than any other era
because of the relatively young, well-preserved rocks associated with
Paleogene spans from the extinction of non-avian dinosaurs, 66
million years ago, to the dawn of the Neogene, 23.03 million years
ago. It features three epochs: the Paleocene,
Eocene and Oligocene.
Paleocene epoch lasted from 66 million to 56 million years ago.
Modern placental mammals originated during this time. The
a transitional point between the devastation that is the K-T
extinction, to the rich jungle environment that is the Early Eocene.
Paleocene saw the recovery of the earth. The continents
began to take their modern shape, but all the continents and the
subcontinent of India were separated from each other.
separated by the Tethys Sea, and the Americas were separated by the
strait of Panama, as the isthmus had not yet formed. This epoch
featured a general warming trend, with jungles eventually reaching the
poles. The oceans were dominated by sharks as the large reptiles
that had once predominated were extinct. Archaic mammals filled the
world such as creodonts (extinct carnivores, unrelated to existing
Eocene Epoch ranged from 56 million years to 33.9 million years
ago. In the Early-Eocene, species living in dense forest were unable
to evolve into larger forms, as in the Paleocene. There was nothing
over the weight of 10 kilograms. Among them were early primates,
whales and horses along with many other early forms of mammals. At the
top of the food chains were huge birds, such as Paracrax. The
temperature was 30 degrees Celsius with little temperature gradient
from pole to pole. In the Mid-Eocene, the Circumpolar-Antarctic
current between Australia and
Antarctica formed. This disrupted ocean
currents worldwide and as a result caused a global cooling effect,
shrinking the jungles. This allowed mammals to grow to mammoth
proportions, such as whales which, by that time, had become almost
fully aquatic. Mammals like
Andrewsarchus were at the top of the
food-chain. The Late
Eocene saw the rebirth of seasons, which caused
the expansion of savanna-like areas, along with the evolution of
grass. The end of the
Eocene was marked by the
Oligocene extinction event, the European face of which is known
as the Grande Coupure.
Oligocene Epoch spans from 33.9 million to 23.03 million years
Oligocene featured the expansion of grass which had led to
many new species to evolve, including the first elephants, cats, dogs,
marsupials and many other species still prevalent today. Many other
species of plants evolved in this period too. A cooling period
featuring seasonal rains was still in effect. Mammals still continued
to grow larger and larger.
Animals of the
Miocene (Chalicotherium, Hyenadon, Entelodont...).
Mammals are the dominant terrestrial vertebrates of the Cenozoic.
Neogene spans from 23.03 million to 2.58 million years ago. It
features 2 epochs: the Miocene, and the Pliocene.
Miocene epoch spans from 23.03 to 5.333 million years ago and is a
period in which grass spread further, dominating a large portion of
the world, at the expense of forests.
Kelp forests evolved,
encouraging the evolution of new species, such as sea otters. During
this time, perissodactyla thrived, and evolved into many different
Apes evolved into 30 species. The
Tethys Sea finally closed
with the creation of the Arabian Peninsula, leaving only remnants as
the Black, Red, Mediterranean and Caspian Seas. This increased
aridity. Many new plants evolved: 95% of modern seed plants evolved in
Pliocene epoch lasted from 5.333 to 2.58 million years ago. The
Pliocene featured dramatic climactic changes, which ultimately led to
modern species and plants. The
Mediterranean Sea dried up for several
million years (because the ice ages reduced sea levels, disconnecting
the Atlantic from the Mediterranean, and evaporation rates exceeded
inflow from rivers).
Australopithecus evolved in Africa, beginning the
human branch. The isthmus of Panama formed, and animals migrated
between North and South America, wreaking havoc on local ecologies.
Climatic changes brought: savannas that are still continuing to spread
across the world; Indian monsoons; deserts in central Asia; and the
beginnings of the
Sahara desert. The world map has not changed much
since, save for changes brought about by the glaciations of the
Quaternary, such as the Great Lakes, Hudson Bay, and the Baltic
Quaternary spans from 2.58 million years ago to present day, and
is the shortest geological period in the
Phanerozoic Eon. It features
modern animals, and dramatic changes in the climate. It is divided
into two epochs: the
Pleistocene and the Holocene.
Megafauna of the
Pleistocene (mammoths, cave lions, woolly rhino,
Pleistocene lasted from 2.58 million to 11,700 years ago. This
epoch was marked by ice ages as a result of the cooling trend that
started in the Mid-Eocene. There were at least four separate
glaciation periods marked by the advance of ice caps as far south as
40 degrees N latitude in mountainous areas. Meanwhile, Africa
experienced a trend of desiccation which resulted in the creation of
the Sahara, Namib, and Kalahari deserts. Many animals evolved
including mammoths, giant ground sloths, dire wolves, saber-toothed
cats, and most famously Homo sapiens. 100,000 years ago marked the end
of one of the worst droughts in Africa, and led to the expansion of
primitive humans. As the
Pleistocene drew to a close, a major
extinction wiped out much of the world's megafauna, including some of
the hominid species, such as Neanderthals. All the continents were
Africa to a lesser extent. It still retains many large
animals, such as hippos.
Holocene began 11,700 years ago and lasts to the present day. All
recorded history and "the history of the world" lies within the
boundaries of the
Holocene epoch. Human activity is blamed for a
mass extinction that began roughly 10,000 years ago, though the
species becoming extinct have only been recorded since the Industrial
Revolution. This is sometimes referred to as the "Sixth Extinction".
Over 322 species have become extinct due to human activity since the
Early in the Cenozoic, following the K-Pg event, the planet was
dominated by relatively small fauna, including small mammals, birds,
reptiles, and amphibians. From a geological perspective, it did not
take long for mammals and birds to greatly diversify in the absence of
the dinosaurs that had dominated during the Mesozoic. Some flightless
birds grew larger than humans. These species are sometimes referred to
as "terror birds," and were formidable predators. Mammals came to
occupy almost every available niche (both marine and terrestrial), and
some also grew very large, attaining sizes not seen in most of today's
Early animals were the
Entelodon (a so-called "hell pig"),
Paraceratherium (a hornless rhinoceros relative) and
early whale). The extinction of many large diapsid groups, such as
Pterosauria allowed mammals and
birds to greatly diversify and become the world's predominant fauna.
Cenozoic is the era when the continents moved into
their current positions. Australia-New Guinea, having split from
Pangea during the early Cretaceous, drifted north and, eventually,
collided with South-east Asia;
Antarctica moved into its current
position over the South Pole; the
Atlantic Ocean widened and, later in
the era (2.8 million years ago),
South America became attached to
North America with the isthmus of Panama.
India collided with
Asia 55 to 45 million years ago creating
the Himalayas; Arabia collided with Eurasia, closing the Tethys Ocean
and creating the Zagros Mountains, around 35 million years
The break-up of Gondwana in Late
Cenozoic times led to
a shift in the river courses of various large African rivers including
the Congo, Niger, Nile, Orange, Limpopo and Zambezi.
Eocene Thermal Maximum at about 55.5 million
years ago was a significant global warming event; however, since the
Azolla event of 49 million years ago, the
Cenozoic Era has been a
period of long-term cooling. After the tectonic creation of Drake
Passage at 41 million years ago, when
South America fully
Antarctica during the Oligocene, the climate cooled
significantly due to the advent of the Antarctic Circumpolar Current
which brought cool deep Antarctic water to the surface. The cooling
trend continued in the Miocene, with relatively short warmer periods.
South America became attached to
North America creating the
Isthmus of Panama
Isthmus of Panama around 2.8 million years ago, the Arctic region
cooled due to the strengthening of the Humboldt and Gulf Stream
currents, eventually leading to the glaciations of the Quaternary
ice age, the current interglacial of which is the
Recent analysis of the geomagnetic reversal frequency, oxygen isotope
record, and tectonic plate subduction rate, which are indicators of
the changes in the heat flux at the core mantle boundary, climate and
plate tectonic activity, shows that all these changes indicate similar
rhythms on million years’ timescale in the
Cenozoic Era occurring
with the common fundamental periodicity of ∼13
Myr during most of
During the Cenozoic, mammals proliferated from a few small, simple,
generalized forms into a diverse collection of terrestrial, marine,
and flying animals, giving this period its other name, the Age of
Mammals, despite the fact that there are more than twice as many bird
species as mammal species. The
Cenozoic is just as much the age of
savannas, the age of co-dependent flowering plants and insects, and
the age of birds.
Grass also played a very important role in this
era, shaping the evolution of the birds and mammals that fed on it.
One group that diversified significantly in the
Cenozoic as well were
the snakes. Evolving in the Cenozoic, the variety of snakes increased
tremendously, resulting in many colubrids, following the evolution of
their current primary prey source, the rodents.
In the earlier part of the Cenozoic, the world was dominated by the
gastornithid birds, terrestrial crocodiles like Pristichampsus, and a
handful of primitive large mammal groups like uintatheres,
mesonychids, and pantodonts. But as the forests began to recede and
the climate began to cool, other mammals took over.
Cenozoic is full of mammals both strange and familiar, including
chalicotheres, creodonts, whales, primates, entelodonts, saber-toothed
cats, mastodons and mammoths, three-toed horses, giant rhinoceros like
Indricotherium, the rhinoceros-like brontotheres, various bizarre
groups of mammals from South America, such as the vaguely
elephant-like pyrotheres and the dog-like marsupial relatives called
borhyaenids and the monotremes and marsupials of Australia.
Paleogene boundary (K–T boundary)
Geologic time scale
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^ Oxford English Dictionary Second Edition, 1989
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ratification of the
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25 (2): 96–102. Bibcode:2010JQS....25...96G.
^ International Stratigraphic Chart
^ Royal Tyrrell Museum (2012-03-28), Lamniform sharks: 110 million
years of ocean supremacy, retrieved 2017-07-12
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Eocene Epoch". University of
^ University of California. "
Eocene Climate". University of
^ National Geographic Society. "Eocene". National Geographic.
^ University of California. "Oligocene". University of
^ Encyclopædia Britannica. "Neogene". Encyclopædia Britannica.
^ University of California. "Miocene". University of California.
^ University of California. "Pliocene". University of
^ Jonathan Adams. "
Pliocene climate". Oak Ridge National Library.
Archived from the original on 25 February 2015.
^ University of California. "Pleistocene". University of
^ University of California. "Holocene". University of
^ Scientific American. "
Sixth Extinction extinctions". Scientific
^ IUCN. "Sixth Extinction". IUCN.
^ Allen, M. B.; Armstrong, H. A. (2008). "Arabia-Eurasia collision and
the forcing of mid
Cenozoic global cooling". Palaeogeography,
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Geologic Time, by Henry Roberts.
After the Dinosaurs: The Age of Mammals, by Donald R. Prothero,
Bloomington, Indiana: Indiana University Press, 2006.
Wikisource has the text of the 1911 Encyclopædia Britannica article
Wikimedia Commons has media related to Cenozoic.
Western Australian Museum – The Age of the Mammals
Geologic history of Earth
Quaternary (present–2.588 Mya)
Holocene (present–11.784 kya)
Pleistocene (11.784 kya–2.588 Mya)
Neogene (2.588–23.03 Mya)
Pliocene (2.588–5.333 Mya)
Miocene (5.333–23.03 Mya)
Paleogene (23.03–66.0 Mya)
Oligocene (23.03–33.9 Mya)
Eocene (33.9–56.0 Mya)
Paleocene (56.0–66.0 Mya)
Cretaceous (66.0–145.0 Mya)
Late (66.0–100.5 Mya)
Early (100.5–145.0 Mya)
Jurassic (145.0–201.3 Mya)
Late (145.0–163.5 Mya)
Middle (163.5–174.1 Mya)
Early (174.1–201.3 Mya)
Triassic (201.3–251.902 Mya)
Late (201.3–237 Mya)
Middle (237–247.2 Mya)
Early (247.2–251.902 Mya)
Permian (251.902–298.9 Mya)
Lopingian (251.902–259.8 Mya)
Guadalupian (259.8–272.3 Mya)
Cisuralian (272.3–298.9 Mya)
Carboniferous (298.9–358.9 Mya)
Pennsylvanian (298.9–323.2 Mya)
Mississippian (323.2–358.9 Mya)
Devonian (358.9–419.2 Mya)
Late (358.9–382.7 Mya)
Middle (382.7–393.3 Mya)
Early (393.3–419.2 Mya)
Silurian (419.2–443.8 Mya)
Pridoli (419.2–423.0 Mya)
Ludlow (423.0–427.4 Mya)
Wenlock (427.4–433.4 Mya)
Llandovery (433.4–443.8 Mya)
Ordovician (443.8–485.4 Mya)
Late (443.8–458.4 Mya)
Middle (458.4–470.0 Mya)
Early (470.0–485.4 Mya)
Cambrian (485.4–541.0 Mya)
Furongian (485.4–497 Mya)
Series 3 (497–509 Mya)
Series 2 (509–521 Mya)
Terreneuvian (521–541.0 Mya)
(541.0 Mya–2.5 Gya)
Neoproterozoic era (541.0 Mya–1 Gya)
Ediacaran (541.0-~635 Mya)
Cryogenian (~635-~720 Mya)
Tonian (~720 Mya-1 Gya)
Mesoproterozoic era (1–1.6 Gya)
Stenian (1-1.2 Gya)
Ectasian (1.2-1.4 Gya)
Calymmian (1.4-1.6 Gya)
Paleoproterozoic era (1.6–2.5 Gya)
Statherian (1.6-1.8 Gya)
Orosirian (1.8-2.05 Gya)
Rhyacian (2.05-2.3 Gya)
Siderian (2.3-2.5 Gya)
Archean eon² (2.5–4 Gya)
Neoarchean (2.5–2.8 Gya)
Mesoarchean (2.8–3.2 Gya)
Paleoarchean (3.2–3.6 Gya)
Eoarchean (3.6–4 Gya)
Hadean eon² (4–4.6 Gya)
kya = thousands years ago. Mya = millions years ago.
Gya = billions
years ago.¹ =
Phanerozoic eon. ² =
Source: (2017/02). International Commission on Stratigraphy. Retrieved
13 July 2015. Divisions of Geologic Time—Major Chronostratigraphic
and Geochronologic Units USGS Retrieved 10 March 2013.