Morphometric analysis of early Eocene Corbisema skeletons (Silicoflagellata) in Mors, Denmark
A two-dimensional morphometric programme, recently designed to measure fossil skeletons of the silicoflagellate genus Corbisema , was used to investigate specimens of the C. apiculata – C. triacantha complex found in a sample from the Fur Formation on the island of Mors, Jutland, Denmark. The semi-a...
Published in: | Journal of Micropalaeontology |
---|---|
Main Authors: | , , , |
Format: | Text |
Language: | English |
Published: |
2019
|
Subjects: | |
Online Access: | https://doi.org/10.5194/jm-37-283-2018 https://jm.copernicus.org/articles/37/283/2018/ |
id |
ftcopernicus:oai:publications.copernicus.org:jm63640 |
---|---|
record_format |
openpolar |
spelling |
ftcopernicus:oai:publications.copernicus.org:jm63640 2023-05-15T15:18:06+02:00 Morphometric analysis of early Eocene Corbisema skeletons (Silicoflagellata) in Mors, Denmark Tsutsui, Hideto Jordan, Richard W. Nishiwaki, Niichi Nishida, Shiro 2019-01-30 application/pdf https://doi.org/10.5194/jm-37-283-2018 https://jm.copernicus.org/articles/37/283/2018/ eng eng doi:10.5194/jm-37-283-2018 https://jm.copernicus.org/articles/37/283/2018/ eISSN: 2041-4978 Text 2019 ftcopernicus https://doi.org/10.5194/jm-37-283-2018 2020-07-20T16:23:26Z A two-dimensional morphometric programme, recently designed to measure fossil skeletons of the silicoflagellate genus Corbisema , was used to investigate specimens of the C. apiculata – C. triacantha complex found in a sample from the Fur Formation on the island of Mors, Jutland, Denmark. The semi-automated programme measured the lengths of the basal sides and radial spines, the basal side curvature, and the location of the pikes (if present) from a photographic database ( N =469 ). As a result, two distinct morphological groups were revealed based on their radial spine length : basal side length ratio and the presence or absence of pikes: group A (ratio of 1 : 1.3, no pikes) and group B, with the latter subdivided into B1 (ratio of 1 : 7, with pikes) and B2 (ratio of 1 : 6, no pikes). Group A ( C. triacantha sensu lato ) possesses a small basal ring with relatively straight basal sides and long radial spines, while group B has a large basal ring with curved basal sides and short radial spines. In B1 specimens ( C. apiculata sensu stricto ) the pikes are positioned 0 to 1 µ m away from the junction point of the strut and basal ring. This would suggest that B1 double skeletons are likely to be in the Star-of-David configuration, while A and B2 double skeletons (which lack pikes) are likely to be in the corner-to-corner configuration. Compared with the previously published biometric studies of extant Stephanocha ( Stephanocha speculum complex in the Southern Ocean and S. medianoctisol in the Arctic Ocean), the results are somewhat different: although C. triacantha sensu lato (group A) is similar to the modern species of Stephanocha , the latter have smaller basal ring diameters, whereas specimens of C. apiculata sensu lato (types B1 and B2) have large basal rings. If their cell diameters are calculated, B1 is the largest, with S. speculum being the smallest – about half the size of B1. This could suggest that the relationship between radial spine length and mean basal ring size has shifted over geological time. Text Arctic Arctic Ocean Southern Ocean Copernicus Publications: E-Journals Arctic Arctic Ocean Southern Ocean Journal of Micropalaeontology 37 1 283 293 |
institution |
Open Polar |
collection |
Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
description |
A two-dimensional morphometric programme, recently designed to measure fossil skeletons of the silicoflagellate genus Corbisema , was used to investigate specimens of the C. apiculata – C. triacantha complex found in a sample from the Fur Formation on the island of Mors, Jutland, Denmark. The semi-automated programme measured the lengths of the basal sides and radial spines, the basal side curvature, and the location of the pikes (if present) from a photographic database ( N =469 ). As a result, two distinct morphological groups were revealed based on their radial spine length : basal side length ratio and the presence or absence of pikes: group A (ratio of 1 : 1.3, no pikes) and group B, with the latter subdivided into B1 (ratio of 1 : 7, with pikes) and B2 (ratio of 1 : 6, no pikes). Group A ( C. triacantha sensu lato ) possesses a small basal ring with relatively straight basal sides and long radial spines, while group B has a large basal ring with curved basal sides and short radial spines. In B1 specimens ( C. apiculata sensu stricto ) the pikes are positioned 0 to 1 µ m away from the junction point of the strut and basal ring. This would suggest that B1 double skeletons are likely to be in the Star-of-David configuration, while A and B2 double skeletons (which lack pikes) are likely to be in the corner-to-corner configuration. Compared with the previously published biometric studies of extant Stephanocha ( Stephanocha speculum complex in the Southern Ocean and S. medianoctisol in the Arctic Ocean), the results are somewhat different: although C. triacantha sensu lato (group A) is similar to the modern species of Stephanocha , the latter have smaller basal ring diameters, whereas specimens of C. apiculata sensu lato (types B1 and B2) have large basal rings. If their cell diameters are calculated, B1 is the largest, with S. speculum being the smallest – about half the size of B1. This could suggest that the relationship between radial spine length and mean basal ring size has shifted over geological time. |
format |
Text |
author |
Tsutsui, Hideto Jordan, Richard W. Nishiwaki, Niichi Nishida, Shiro |
spellingShingle |
Tsutsui, Hideto Jordan, Richard W. Nishiwaki, Niichi Nishida, Shiro Morphometric analysis of early Eocene Corbisema skeletons (Silicoflagellata) in Mors, Denmark |
author_facet |
Tsutsui, Hideto Jordan, Richard W. Nishiwaki, Niichi Nishida, Shiro |
author_sort |
Tsutsui, Hideto |
title |
Morphometric analysis of early Eocene Corbisema skeletons (Silicoflagellata) in Mors, Denmark |
title_short |
Morphometric analysis of early Eocene Corbisema skeletons (Silicoflagellata) in Mors, Denmark |
title_full |
Morphometric analysis of early Eocene Corbisema skeletons (Silicoflagellata) in Mors, Denmark |
title_fullStr |
Morphometric analysis of early Eocene Corbisema skeletons (Silicoflagellata) in Mors, Denmark |
title_full_unstemmed |
Morphometric analysis of early Eocene Corbisema skeletons (Silicoflagellata) in Mors, Denmark |
title_sort |
morphometric analysis of early eocene corbisema skeletons (silicoflagellata) in mors, denmark |
publishDate |
2019 |
url |
https://doi.org/10.5194/jm-37-283-2018 https://jm.copernicus.org/articles/37/283/2018/ |
geographic |
Arctic Arctic Ocean Southern Ocean |
geographic_facet |
Arctic Arctic Ocean Southern Ocean |
genre |
Arctic Arctic Ocean Southern Ocean |
genre_facet |
Arctic Arctic Ocean Southern Ocean |
op_source |
eISSN: 2041-4978 |
op_relation |
doi:10.5194/jm-37-283-2018 https://jm.copernicus.org/articles/37/283/2018/ |
op_doi |
https://doi.org/10.5194/jm-37-283-2018 |
container_title |
Journal of Micropalaeontology |
container_volume |
37 |
container_issue |
1 |
container_start_page |
283 |
op_container_end_page |
293 |
_version_ |
1766348323880435712 |