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The evolution of Neogloboquadrina pachyderma (Ehrenberg) in the central Arctic Ocean and a comparison to its evolution in the North Atlantic Ocean.

Record Type:	Electronic resources : Monograph/item
Title/Author:	The evolution of Neogloboquadrina pachyderma (Ehrenberg) in the central Arctic Ocean and a comparison to its evolution in the North Atlantic Ocean./
Author:	Atkins, Elizabeth Dale.
Description:	1 online resource (214 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 53-08, Section: B.
Contained By:	Dissertations Abstracts International53-08B.
Subject:	Paleontology. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9134306click for full text (PQDT)
ISBN:	9798207420042

The evolution of Neogloboquadrina pachyderma (Ehrenberg) in the central Arctic Ocean and a comparison to its evolution in the North Atlantic Ocean.
Atkins, Elizabeth Dale.

The evolution of Neogloboquadrina pachyderma (Ehrenberg) in the central Arctic Ocean and a comparison to its evolution in the North Atlantic Ocean. - 1 online resource (214 pages)

Source: Dissertations Abstracts International, Volume: 53-08, Section: B.

Thesis (Ph.D.)--The University of Wisconsin - Madison, 1991.

Includes bibliographical references

A morphometric analysis of Neogloboquadrina pachyderma (Ehrenberg) shows that this species has been fairly uniform in terms of shape, coiling direction and other morphological characters throughout the Pleistocene-Holocene in the central Arctic Ocean (CAO). This implies that the CAO has been a relatively stable environment for this species of planktonic foraminifer. The comparison of the evolution of the planktonic foraminifer Neogloboquadrina pachyderma in the CAO and in the North Atlantic Ocean (NAO) shows that since the early Pleistocene, CAO Neogloboquadrina pachyderma have been smaller and more uniform in shape than NAO morphs. Neogloboquadrina pachyderma specimens from both oceans were approximately the same size and shape in the early Pleistocene and have since diverged. The shape and coiling direction of N. pachyderma specimens from the NAO reflect the greater heterogeneity of the NAO environment in terms of upper water mass differences both east to west and north to south and through time. Seventy percent or more of N. pachyderma from both oceans exhibited a complex pattern of growth in which one or more of the chambers in the final whorl is smaller than the preceding chamber (defined herein as heteroform growth). In both oceans, N. pachyderma show a non-linear size change from the late Miocene to Holocene. The mid-late Pliocene NAO and late Pliocene-Holocene for the CAO and NAO represent times when N. pachyderma was largest in average size and size range. NAO N. pachyderma are smallest in the early Pleistocene and CAO specimens are smallest in the mid Pleistocene. CAO N. pachyderma size changes may be indicative of enhanced circulation in the mid Pleistocene at least in the northern hemisphere. Three CAO N. pachyderma size morphozones are defined for the early Pleistocene, mid Pliestocene and the late Pleistocene-Holocene.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9798207420042Subjects--Topical Terms:

518862
Paleontology.
Subjects--Index Terms:

HoloceneIndex Terms--Genre/Form:

542853
Electronic books.

The evolution of Neogloboquadrina pachyderma (Ehrenberg) in the central Arctic Ocean and a comparison to its evolution in the North Atlantic Ocean.
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100 1 $a Atkins, Elizabeth Dale. $3 3700972
245 1 4 $a The evolution of Neogloboquadrina pachyderma (Ehrenberg) in the central Arctic Ocean and a comparison to its evolution in the North Atlantic Ocean.
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500 $a Source: Dissertations Abstracts International, Volume: 53-08, Section: B.
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500 $a Advisor: Clark, David L.
502 $a Thesis (Ph.D.)--The University of Wisconsin - Madison, 1991.
504 $a Includes bibliographical references
520 $a A morphometric analysis of Neogloboquadrina pachyderma (Ehrenberg) shows that this species has been fairly uniform in terms of shape, coiling direction and other morphological characters throughout the Pleistocene-Holocene in the central Arctic Ocean (CAO). This implies that the CAO has been a relatively stable environment for this species of planktonic foraminifer. The comparison of the evolution of the planktonic foraminifer Neogloboquadrina pachyderma in the CAO and in the North Atlantic Ocean (NAO) shows that since the early Pleistocene, CAO Neogloboquadrina pachyderma have been smaller and more uniform in shape than NAO morphs. Neogloboquadrina pachyderma specimens from both oceans were approximately the same size and shape in the early Pleistocene and have since diverged. The shape and coiling direction of N. pachyderma specimens from the NAO reflect the greater heterogeneity of the NAO environment in terms of upper water mass differences both east to west and north to south and through time. Seventy percent or more of N. pachyderma from both oceans exhibited a complex pattern of growth in which one or more of the chambers in the final whorl is smaller than the preceding chamber (defined herein as heteroform growth). In both oceans, N. pachyderma show a non-linear size change from the late Miocene to Holocene. The mid-late Pliocene NAO and late Pliocene-Holocene for the CAO and NAO represent times when N. pachyderma was largest in average size and size range. NAO N. pachyderma are smallest in the early Pleistocene and CAO specimens are smallest in the mid Pleistocene. CAO N. pachyderma size changes may be indicative of enhanced circulation in the mid Pleistocene at least in the northern hemisphere. Three CAO N. pachyderma size morphozones are defined for the early Pleistocene, mid Pliestocene and the late Pleistocene-Holocene.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2023
538 $a Mode of access: World Wide Web
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650 4 $a Geology. $3 516570
650 4 $a Oceanography. $3 535383
650 4 $a Physical oceanography. $3 3168433
653 $a Holocene
653 $a Pleistocene
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773 0 $t Dissertations Abstracts International $g 53-08B.
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9134306 $z click for full text (PQDT)