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The Paleogene (/ˈpæliədʒiːn, ˈpeɪliə-/; also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period and system that spans 43 million years from the end of the Cretaceous
Cretaceous
Period 66 million years ago (Mya) to the beginning of the Neogene
Neogene
Period 23.03 Mya. It is the beginning of the Cenozoic
Cenozoic
Era of the present Phanerozoic
Phanerozoic
Eon.[7] The Paleogene is most notable for being the time during which mammals diversified from relatively small, simple forms into a large group of diverse animals in the wake of the Cretaceous–Paleogene extinction event
Cretaceous–Paleogene extinction event
that ended the preceding Cretaceous
Cretaceous
Period.[8] This period consists of the Paleocene, Eocene, and Oligocene
Oligocene
epochs. The end of the Paleocene
Paleocene
(55.5/54.8 Mya) was marked by the Paleocene– Eocene
Eocene
Thermal Maximum, one of the most significant periods of global change during the Cenozoic, which upset oceanic and atmospheric circulation and led to the extinction of numerous deep-sea benthic foraminifera and on land, a major turnover in mammals. The terms ' Paleogene System' (formal) and 'lower Tertiary System' (informal) are applied to the rocks deposited during the 'Paleogene Period'. The somewhat confusing terminology seems to be due to attempts to deal with the comparatively fine subdivisions of time possible in the relatively recent geologic past, for which more details are preserved. By dividing the Tertiary Period into two periods instead of directly into five epochs, the periods are more closely comparable to the duration of 'periods' of the preceding Mesozoic
Mesozoic
and Paleozoic
Paleozoic
Eras.

Contents

1 Climate and geography 2 Flora and fauna 3 Geology

3.1 Oil industry relevance

4 References 5 External links

Climate and geography[edit]

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The global climate during the Paleogene departed from the hot and humid conditions of the late Mesozoic
Mesozoic
era and began a cooling and drying trend which, despite having been periodically disrupted by warm periods such as the Paleocene– Eocene
Eocene
Thermal Maximum, persists today. The trend was partly caused by the formation of the Antarctic Circumpolar Current, which significantly lowered oceanic water temperatures. During the Paleogene, the continents continued to drift closer to their current positions. India
India
was in the process of colliding with Asia, subsequently forming the Himalayas. The Atlantic Ocean
Atlantic Ocean
continued to widen by a few centimeters each year. Africa was moving north to meet with Europe and form the Mediterranean, while South America was moving closer to North America
North America
(they would later connect via the Isthmus of Panama). Inland seas retreated from North America
North America
early in the period. Australia had also separated from Antarctica and was drifting toward Southeast Asia. Flora and fauna[edit]

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Mammals began a rapid diversification during this period. After the Cretaceous– Paleogene extinction event, which saw the demise of the non-avian dinosaurs, mammals transformed from a few small and generalized forms that began to evolve into most of the modern varieties we see today. Some of these mammals would evolve into large forms that would dominate the land, while others would become capable of living in marine, specialized terrestrial, and airborne environments. Those that took to the oceans became modern cetaceans, while those that took to the trees became primates, the group to which humans belong. Birds, which were already well established by the end of the Cretaceous, also experienced an adaptive radiation as they took over the skies left empty by the now extinct Pterosaurs. In comparison to birds and mammals, most other branches of life remained relatively unchanged during this period. As the Earth cooled, tropical plants became less numerous and were now restricted to equatorial regions. Deciduous plants, which could survive through the seasonal climates the world was now experiencing, became more common.

Geology[edit] Oil industry relevance[edit] The Paleogene is notable in the context of offshore oil drilling, and especially in Gulf of Mexico
Gulf of Mexico
oil exploration, where it is commonly referred to as the "Lower Tertiary". These rock formations represent the current cutting edge of deep-water oil discovery. Lower Tertiary rock formations encountered in the Gulf of Mexico
Gulf of Mexico
oil industry usually tend to be comparatively high temperature and high pressure reservoirs, often with high sand content (70%+) or under very thick evaporite sediment layers.[9] Lower Tertiary explorations to date include (partial list):

Kaskida Oil Field Tiber Oil Field Jack 2

References[edit]

^ Image:Sauerstoffgehalt-1000mj.svg ^ File:OxygenLevel-1000ma.svg ^ Image: Phanerozoic
Phanerozoic
Carbon Dioxide.png ^ Image:All palaeotemps.png ^ Retallack, G. J. (1997). " Neogene
Neogene
Expansion of the North American Prairie". PALAIOS. 12 (4): 380–390. doi:10.2307/3515337. JSTOR 3515337. Retrieved 2008-02-11.  ^ Zachos, J. C.; Kump, L. R. (2005). "Carbon cycle feedbacks and the initiation of Antarctic glaciation in the earliest Oligocene". Global and Planetary Change. 47 (1): 51–66. Bibcode:2005GPC....47...51Z. doi:10.1016/j.gloplacha.2005.01.001.  ^ Formerly, the period covered by the Paleogene was called the first part of the Tertiary, whose usage is no longer official. "Whatever happened to the Tertiary and Quaternary?" ^ Robert W. Meredith, Jan E. Janecka, John Gatesy, Oliver A. Ryder, Colleen A. Fisher, Emma C. Teeling, Alisha Goodbla, Eduardo Eizirik, Taiz L. L. Simão, Tanja Stadler, Daniel L. Rabosky, Rodney L. Honeycutt, John J. Flynn, Colleen M. Ingram, Cynthia Steiner, Tiffani L. Williams, Terence J. Robinson, Angela Burk-Herrick, Michael Westerman, Nadia A. Ayoub, Mark S. Springer, William J. Murphy. 2011. Impacts of the Cretaceous
Cretaceous
Terrestrial Revolution and KPg extinction on mammal diversification. Science 334:521-524. ^ "Lower Tertiary". Halliburton. Archived from the original on 2011-09-29. Retrieved 2011-07-13. 

External links[edit]

Wikisource has original works on the topic: Cenozoic#Paleogene

Wikimedia Commons has media related to Paleogene.

Paleogene Microfossils: 180+ images of Foraminifera

v t e

Paleogene Period

Paleocene
Paleocene
Epoch Eocene
Eocene
Epoch Oligocene
Oligocene
Epoch

Danian Selandian Thanetian

Ypresian Lutetian Bartonian Priabonian

Rupelian Chattian

v t e

Geologic history of Earth

Cenozoic
Cenozoic
era¹ (present–66.0 Mya)

Quaternary
Quaternary
(present–2.588 Mya)

Holocene
Holocene
(present–11.784 kya) Pleistocene
Pleistocene
(11.784 kya–2.588 Mya)

Neogene
Neogene
(2.588–23.03 Mya)

Pliocene
Pliocene
(2.588–5.333 Mya) Miocene
Miocene
(5.333–23.03 Mya)

Paleogene (23.03–66.0 Mya)

Oligocene
Oligocene
(23.03–33.9 Mya) Eocene
Eocene
(33.9–56.0 Mya) Paleocene
Paleocene
(56.0–66.0 Mya)

Mesozoic
Mesozoic
era¹ (66.0–251.902 Mya)

Cretaceous
Cretaceous
(66.0–145.0 Mya)

Late (66.0–100.5 Mya) Early (100.5–145.0 Mya)

Jurassic
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
Triassic
(201.3–251.902 Mya)

Late (201.3–237 Mya) Middle (237–247.2 Mya) Early (247.2–251.902 Mya)

Paleozoic
Paleozoic
era¹ (251.902–541.0 Mya)

Permian
Permian
(251.902–298.9 Mya)

Lopingian
Lopingian
(251.902–259.8 Mya) Guadalupian
Guadalupian
(259.8–272.3 Mya) Cisuralian
Cisuralian
(272.3–298.9 Mya)

Carboniferous
Carboniferous
(298.9–358.9 Mya)

Pennsylvanian (298.9–323.2 Mya) Mississippian (323.2–358.9 Mya)

Devonian
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
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
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
Cambrian
(485.4–541.0 Mya)

Furongian (485.4–497 Mya) Series 3 (497–509 Mya) Series 2 (509–521 Mya) Terreneuvian
Terreneuvian
(521–541.0 Mya)

Proterozoic
Proterozoic
eon² (541.0 Mya–2.5 Gya)

Neoproterozoic era (541.0 Mya–1 Gya)

Ediacaran
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
Orosirian
(1.8-2.05 Gya) Rhyacian (2.05-2.3 Gya) Siderian
Siderian
(2.3-2.5 Gya)

Archean
Archean
eon² (2.5–4 Gya)

Eras

Neoarchean (2.5–2.8 Gya) Mesoarchean (2.8–3.2 Gya) Paleoarchean
Paleoarchean
(3.2–3.6 Gya) Eoarchean
Eoarchean
(3.6–4 Gya)

Hadean
Hadean
eon² (4–4.6 Gya)

 

 

kya = thousands years ago. Mya = millions years ago. Gya = billions years ago.¹ = Phanerozoic
Phanerozoic
eon. ² = Precambrian
Precambrian
supereon. 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.

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