Pennsylvanian


Pennsylvanian
System Subsystem/
Series
Stage Age
(Ma)
Permian Cisuralian Asselian younger
Carboniferous Pennsylvanian Gzhelian 299.0–303.9
Kasimovian 303.9–306.5
Moscovian 306.5–311.7
Bashkirian 311.7–318.1
Mississippian Serpukhovian 318.1–328.3
Viséan 328.3–345.3
Tournaisian 345.3–359.2
Devonian Upper Famennian older
Subdivision of the Carboniferous system according to the ICS.[1]

The Pennsylvanian is, in the ICS geologic timescale, the younger of two subperiods (or upper of two subsystems) of the Carboniferous Period. It lasted from roughly 318.1 ± 1.3 to 299 ± 0.8. As with most other geochronologic units, the rock beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain by a few million years. The Pennsylvanian is named after the American state of Pennsylvania, where rocks with this age are widespread.

Generalized geographic map of the United States in middle Pennsylvanian time.

The division between Pennsylvanian and Mississippian comes from North American stratigraphy. In North America, where the early Carboniferous beds are primarily marine limestones, the Pennsylvanian was in the past treated as a full fledged geologic period between the Mississippian and the Permian. In Europe, the Mississippian and Pennsylvanian are one more-or-less continuous sequence of lowland continental deposits and are grouped together as the Carboniferous Period. The current internationally used geologic timescale of the ICS gives the Mississippian and Pennsylvanian the rank of subperiods, subdivisions of the Carboniferous Period.

Contents

Life

Fungi

All modern classes of fungi were present in the Pennsylvanian.[2]

Vertebrates

Amphibians were diverse and common; some were several meters long as adults. The collapse of the rainforest ecology in the mid Pennsylvanian (between the Moscovian and the Kasimovian) removed many amphibian species that did not survive as well in the cooler, drier conditions. Reptiles, however, prospered due to specific key adaptations.[3] One of the greatest evolutionary innovations of the Carboniferous was the amniote egg, which allowed for the further exploitation of the land by certain tetrapods. These included the earliest sauropsid reptiles (Hylonomus), and the earliest known synapsid (Archaeothyris). These small lizard-like animals quickly gave rise to many descendants. Reptiles underwent a major evolutionary radiation, in response to the drier climate that proceeded the rainforest collapse.[3][4]

Subdivisions

The Pennsylvanian has been variously subdivided. The international timescale of the ICS follows the Russian subdivision into four stages:

North American subdivision is into five stages, but not precisely the same, with additional (older) Appalachian series names following:

  • Morrowan stage, corresponding with the middle and lower part of the Pottsville Group (oldest)
  • Atokan stage, corresponding with the upper part of the Pottsville group
  • Desmoinesian stage, corresponding with the Allegheny Group
  • Missourian stage, corresponding with the Conemaugh Group
  • Virgilian stage, corresponding with the Monongahela Group (youngest)

The Virgilian or Conemaugh corresponds to the Gzhelian plus the uppermost Kasimovian. The Missourian or Monongahela corresponds to the rest of the Kasimovian. The Desmoinesian or Allegheny corresponds to the upper half of the Moscovian. The Atokan or upper Pottsville corresponds to the lower half of the Moscovian. The Morrowan corresponds to the Bashkirian.

In the European subdivision, the Carboniferous is divided into two epochs: Dinantian (early) and Silesian (late). The Silesian starts earlier than the Pennsylvanian and is divided in three ages:

  • Namurian (corresponding to Serpukhovian and early Bashkirian)
  • Westphalian (corresponding to late Bashkirian, Moskovian and Kasimovian)
  • Stephanian (corresponding to Gzelian).

References

  1. ^ Gradstein et al. (2004)
  2. ^ Blackwell, Meredith, Vilgalys, Rytas, James, Timothy Y., and Taylor, John W. Fungi. Eumycota: mushrooms, sac fungi, yeast, molds, rusts, smuts, etc., February 2008, Tree of Life Web Project
  3. ^ a b Sahney, S., Benton, M.J. & Falcon-Lang, H.J. (2010). "Rainforest collapse triggered Pennsylvanian tetrapod diversification in Euramerica" (PDF). Geology 38 (12): 1079–1082. doi:10.1130/G31182.1. http://geology.geoscienceworld.org/cgi/content/abstract/38/12/1079. 
  4. ^ M. Alan Kazlev (1998) The Carboniferous Period of the Paleozoic Era: 299 to 359 million years ago, Palaeos.org, Retrieved on 2008-06-23

External links


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Look at other dictionaries:

  • Pennsylvanian — ☆ Pennsylvanian [pen΄səl vān′yən, pen΄səlvā′nē ən ] adj. 1. of Pennsylvania 2. [sometimes p ] designating or of the second and last geologic subdivision of the Carboniferous Period, characterized by the development of vast deposits of dead, coal… …   English World dictionary

  • Pennsylvanian — adjective Date: 1698 1. of or relating to Pennsylvania or its people 2. of, relating to, or being the period of the Paleozoic era in North America between the Mississippian and Permian or the corresponding system of rocks see geologic time table… …   New Collegiate Dictionary

  • Pennsylvanian — /pen seuhl vayn yeuhn, vay nee euhn/, adj. 1. of or pertaining to the state of Pennsylvania. 2. Geol. noting or pertaining to a period of the Paleozoic Era, occurring from about 310 to 280 million years ago and characterized by warm climates,… …   Universalium

  • Pennsylvanian — 1. noun a) An inhabitant or a resident of the state of Pennsylvania. b) Any of the three Pennsylvanian epochs. 2. adjective a) of any of the three …   Wiktionary

  • Pennsylvanian — Penn•syl•va•nian [[t]ˌpɛn səlˈveɪn yən, ˈveɪ ni ən[/t]] adj. 1) of or pertaining to the state of Pennsylvania 2) gel of or pertaining to a period of the Paleozoic Era, occurring from about 310 to 280 million years ago and characterized by warm… …   From formal English to slang

  • Pennsylvanian — System Subsystem Stufe ≈ Alter (mya) höher höher höher jünger Karbon Pennsylvanium Gzhelium …   Deutsch Wikipedia

  • pennsylvanian —   a period of geologic time lasing from 320m to 286m years ago …   Geography glossary

  • Pennsylvanian — n. resident of Pennsylvania (USA) adj. pertaining to Pennsylvania (USA) …   English contemporary dictionary

  • Pennsylvanian — noun a native or inhabitant of the US state of Pennsylvania. adjective 1》 relating to Pennsylvania. 2》 Geology of or denoting the later part of the Carboniferous period in North America …   English new terms dictionary

  • pennsylvanian — penn·syl·va·nian …   English syllables


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