On a grain of sand – a microhabitat for the opportunistic agglutinated foraminifera Hemisphaerammina apta n. sp., from the early Eocene Arctic Ocean
Hemisphaerammina apta n. sp. is an attached monothalamous agglutinated foraminifera discovered in shelf sediments of the early Eocene Arctic Ocean. It is a simple yet distinctive component of the endemic agglutinated foraminiferal assemblage that colonized the Arctic Ocean after the microfaunal turn...
Published in: | Journal of Micropalaeontology |
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ftcopernicus:oai:publications.copernicus.org:jm63645 2023-05-15T14:51:10+02:00 On a grain of sand – a microhabitat for the opportunistic agglutinated foraminifera Hemisphaerammina apta n. sp., from the early Eocene Arctic Ocean McNeil, David H. Neville, Lisa A. 2018-09-27 application/pdf https://doi.org/10.5194/jm-37-295-2018 https://jm.copernicus.org/articles/37/295/2018/ eng eng doi:10.5194/jm-37-295-2018 https://jm.copernicus.org/articles/37/295/2018/ eISSN: 2041-4978 Text 2018 ftcopernicus https://doi.org/10.5194/jm-37-295-2018 2020-07-20T16:23:25Z Hemisphaerammina apta n. sp. is an attached monothalamous agglutinated foraminifera discovered in shelf sediments of the early Eocene Arctic Ocean. It is a simple yet distinctive component of the endemic agglutinated foraminiferal assemblage that colonized the Arctic Ocean after the microfaunal turnover caused by the Paleocene–Eocene Thermal Maximum. Associated foraminifera are characterized by a high percentage of monothalamous species (up to 60 %) and are entirely agglutinated indicating a brackish (mesohaline) early Eocene Arctic Ocean. Hemisphaerammina apta occurs exclusively as individuals attached to fine detrital grains (0.2 to 1.8 mm) of sediment. It is a small species (0.06 to 0.2 mm in diameter), fine-grained, with a low hemispherical profile, no floor across the attachment area, no substantive marginal flange, no internal structures, and no aperture. Lacking an aperture, it apparently propagated and fed through minute (micrometre-sized) interstitial pores in the test wall. Attachment surfaces vary from concave to convex and rough to smooth. Grains for attachment are diverse in shape and type but are predominantly of quartz and chert. The presence of H. apta in the early Eocene was an opportunistic response to an environment with an active hydrological system (storm events). Attachment to grains of sand would provide a more stable base on a sea floor winnowed by storm-generated currents. Active transport is indicated by the relative abundance of reworked foraminifera mixed with in situ species. Contemporaneous reworking and colonization by H. apta is suggested by its attachment to a reworked specimen of Cretaceous foraminifera. Text Arctic Arctic Ocean Foraminifera* Copernicus Publications: E-Journals Arctic Arctic Ocean Journal of Micropalaeontology 37 1 295 303 |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
Hemisphaerammina apta n. sp. is an attached monothalamous agglutinated foraminifera discovered in shelf sediments of the early Eocene Arctic Ocean. It is a simple yet distinctive component of the endemic agglutinated foraminiferal assemblage that colonized the Arctic Ocean after the microfaunal turnover caused by the Paleocene–Eocene Thermal Maximum. Associated foraminifera are characterized by a high percentage of monothalamous species (up to 60 %) and are entirely agglutinated indicating a brackish (mesohaline) early Eocene Arctic Ocean. Hemisphaerammina apta occurs exclusively as individuals attached to fine detrital grains (0.2 to 1.8 mm) of sediment. It is a small species (0.06 to 0.2 mm in diameter), fine-grained, with a low hemispherical profile, no floor across the attachment area, no substantive marginal flange, no internal structures, and no aperture. Lacking an aperture, it apparently propagated and fed through minute (micrometre-sized) interstitial pores in the test wall. Attachment surfaces vary from concave to convex and rough to smooth. Grains for attachment are diverse in shape and type but are predominantly of quartz and chert. The presence of H. apta in the early Eocene was an opportunistic response to an environment with an active hydrological system (storm events). Attachment to grains of sand would provide a more stable base on a sea floor winnowed by storm-generated currents. Active transport is indicated by the relative abundance of reworked foraminifera mixed with in situ species. Contemporaneous reworking and colonization by H. apta is suggested by its attachment to a reworked specimen of Cretaceous foraminifera. |
format |
Text |
author |
McNeil, David H. Neville, Lisa A. |
spellingShingle |
McNeil, David H. Neville, Lisa A. On a grain of sand – a microhabitat for the opportunistic agglutinated foraminifera Hemisphaerammina apta n. sp., from the early Eocene Arctic Ocean |
author_facet |
McNeil, David H. Neville, Lisa A. |
author_sort |
McNeil, David H. |
title |
On a grain of sand – a microhabitat for the opportunistic agglutinated foraminifera Hemisphaerammina apta n. sp., from the early Eocene Arctic Ocean |
title_short |
On a grain of sand – a microhabitat for the opportunistic agglutinated foraminifera Hemisphaerammina apta n. sp., from the early Eocene Arctic Ocean |
title_full |
On a grain of sand – a microhabitat for the opportunistic agglutinated foraminifera Hemisphaerammina apta n. sp., from the early Eocene Arctic Ocean |
title_fullStr |
On a grain of sand – a microhabitat for the opportunistic agglutinated foraminifera Hemisphaerammina apta n. sp., from the early Eocene Arctic Ocean |
title_full_unstemmed |
On a grain of sand – a microhabitat for the opportunistic agglutinated foraminifera Hemisphaerammina apta n. sp., from the early Eocene Arctic Ocean |
title_sort |
on a grain of sand – a microhabitat for the opportunistic agglutinated foraminifera hemisphaerammina apta n. sp., from the early eocene arctic ocean |
publishDate |
2018 |
url |
https://doi.org/10.5194/jm-37-295-2018 https://jm.copernicus.org/articles/37/295/2018/ |
geographic |
Arctic Arctic Ocean |
geographic_facet |
Arctic Arctic Ocean |
genre |
Arctic Arctic Ocean Foraminifera* |
genre_facet |
Arctic Arctic Ocean Foraminifera* |
op_source |
eISSN: 2041-4978 |
op_relation |
doi:10.5194/jm-37-295-2018 https://jm.copernicus.org/articles/37/295/2018/ |
op_doi |
https://doi.org/10.5194/jm-37-295-2018 |
container_title |
Journal of Micropalaeontology |
container_volume |
37 |
container_issue |
1 |
container_start_page |
295 |
op_container_end_page |
303 |
_version_ |
1766322219868225536 |