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2019-10-22 10:23:37.0 [tstevens] Insert Concept
add narrower relation (PALEOCENE [cb277225-be9e-4c22-954e-fe7352e9faa6,336105] - THANETIAN
[979bcb67-30f0-49c8-8e8e-fb7412e75efa,369457]);
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2019-10-22 10:23:58.0 [tstevens] Insert Concept
add narrower relation (PALEOCENE [cb277225-be9e-4c22-954e-fe7352e9faa6,336105] - SELANDIAN
[1f28f84d-f0ab-484e-8eea-2c9f5c141558,369461]);
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2019-10-22 10:24:16.0 [tstevens] Insert Concept
add narrower relation (PALEOCENE [cb277225-be9e-4c22-954e-fe7352e9faa6,336105] - DANIAN
[f2053865-d144-4d79-b18b-4fd361be25ae,369465]);
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2019-10-23 08:28:44.0 [tstevens]
insert Definition (id: null
text: The Paleocene is a geological epoch that lasted from about 66 to 56 million
years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic
Era.
The epoch is bracketed by two major events in Earth's history: the K-Pg extinction
event and the Paleocene–Eocene thermal maximum. The K-Pg extinction event, brought
on by an asteroid impact and an ensuing impact winter, marked the beginning of the
Paleocene and killed off 75% of life on Earth, most famously the non-avian dinosaurs.
The end of the epoch was marked by the Paleocene–Eocene thermal maximum, which was
a major climatic event wherein about 2,500–4,500 gigatons of carbon was released into
the atmosphere and ocean systems en masse, causing a spike in global temperatures
and ocean acidification.
The Paleocene continued many geological processes initiated in Mesozoic, and the continents
continued moving towards their present positions. The Northern Hemisphere continents
were still connected via some land bridges as well as the Southern Hemisphere continents,
the Rocky Mountains were being uplifted, the Americas had not yet joined, and the
Indian Plate had begun its collision with Asia. In the oceans, the thermohaline circulation
probably was much different than it is today, with downwellings occurring in the North
Pacific rather than the North Atlantic, and water density was mainly controlled by
salinity rather than temperature.
The extinction event caused a floral and faunal turnover of species, with previously
abundant species being replaced by previously uncommon ones. With a global average
temperature of about 24–25 °C (75–77 °F), compared to 14 °C (57 °F) in more recent
times, the Earth had a greenhouse climate without permanent ice sheets at the poles.
As such, there were forests worldwide–including at the poles–with low species richness
in regards to plant life, populated by mainly small creatures which were rapidly evolving
to take advantage of the recently-emptied Earth. Though some animals attained enormous
size, most remained rather small. The forests grew quite dense in the general absence
of large herbivores. Mammals proliferated in the Paleocene, and the earliest placentals
and marsupials are recorded from this time, but most Paleocene taxa have ambiguous
affinities. In the seas, ray-finned fish rose to dominate open ocean and reef ecosystems.
language code: en);
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| definition |
The Paleocene is a geological epoch that lasted from about 66 to 56 million years
ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era.
The epoch is bracketed by two major events in Earth's history: the K-Pg extinction
event and the Paleocene–Eocene thermal maximum. The K-Pg extinction event, brought
on by an asteroid impact and an ensuing impact winter, marked the beginning of the
Paleocene and killed off 75% of life on Earth, most famously the non-avian dinosaurs.
The end of the epoch was marked by the Paleocene–Eocene thermal maximum, which was
a major climatic event wherein about 2,500–4,500 gigatons of carbon was released into
the atmosphere and ocean systems en masse, causing a spike in global temperatures
and ocean acidification.
The Paleocene continued many geological processes initiated in Mesozoic, and the continents
continued moving towards their present positions. The Northern Hemisphere continents
were still connected via some land bridges as well as the Southern Hemisphere continents,
the Rocky Mountains were being uplifted, the Americas had not yet joined, and the
Indian Plate had begun its collision with Asia. In the oceans, the thermohaline circulation
probably was much different than it is today, with downwellings occurring in the North
Pacific rather than the North Atlantic, and water density was mainly controlled by
salinity rather than temperature.
The extinction event caused a floral and faunal turnover of species, with previously
abundant species being replaced by previously uncommon ones. With a global average
temperature of about 24–25 °C (75–77 °F), compared to 14 °C (57 °F) in more recent
times, the Earth had a greenhouse climate without permanent ice sheets at the poles.
As such, there were forests worldwide–including at the poles–with low species richness
in regards to plant life, populated by mainly small creatures which were rapidly evolving
to take advantage of the recently-emptied Earth. Though some animals attained enormous
size, most remained rather small. The forests grew quite dense in the general absence
of large herbivores. Mammals proliferated in the Paleocene, and the earliest placentals
and marsupials are recorded from this time, but most Paleocene taxa have ambiguous
affinities. In the seas, ray-finned fish rose to dominate open ocean and reef ecosystems.
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