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Three dimensional reconstructions of Nummulites tests reveal complex chamber shapes.

Renema W, Cotton L - PeerJ (2015)

Bottom Line: During the Paleogene the genus Nummulites was particularly abundant with a global distribution, leading it to be frequently used in biostratigraphy.Here we apply micro computed-tomographical scanning, a tool that recently has become available, to visualise 3D chamber shape of Nummulites djokdjokartae and compare these to traditional morphometrical characters.We argue that 3D reconstructions of Nummulites tests will be a great aid in improving our understanding of lineages within the genus Nummulites, and to elucidate its evolutionary and biogeographical history.

View Article: PubMed Central - HTML - PubMed

Affiliation: Naturalis Biodiversity Center , CR Leiden , The Netherlands.

ABSTRACT
Larger benthic foraminifera (LBF) are important and prolific carbonate producers both in modern and ancient shallow tropical seas. During the Paleogene the genus Nummulites was particularly abundant with a global distribution, leading it to be frequently used in biostratigraphy. However, their evolution is poorly understood as classification is Europe-centered and mostly based on external characters and equatorial thin sections. New occurrences from regions outside the northern Tethys which poorly fit in thus reference frame, show that a more rigid framework for the classification of Nummulites is needed. Here we apply micro computed-tomographical scanning, a tool that recently has become available, to visualise 3D chamber shape of Nummulites djokdjokartae and compare these to traditional morphometrical characters. We find that despite the regular shape in equatorial and axial thin section the irregular 3D chamber shape is not predicted by these sections. We argue that 3D reconstructions of Nummulites tests will be a great aid in improving our understanding of lineages within the genus Nummulites, and to elucidate its evolutionary and biogeographical history.

No MeSH data available.


Related in: MedlinePlus

Chamber shape per whorl in specimen 06KW01_05.Note the increase in complexity of chamber shape. (A) whorl 1; (B) whorl 2; (C) whorl 3; (D) whorl 4; (E) whorl 5; (G) first half of whorl 6; (H) second half of whorl 6. In yellow and red that could not attributed to a chamber with certainty are indicated. Note that in whorl 6 the alar prolongations of half a whorl cover up to 3/4 of the test. Scale bar is 250 µm. 3D movies of this figure are in the SOM.
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fig-2: Chamber shape per whorl in specimen 06KW01_05.Note the increase in complexity of chamber shape. (A) whorl 1; (B) whorl 2; (C) whorl 3; (D) whorl 4; (E) whorl 5; (G) first half of whorl 6; (H) second half of whorl 6. In yellow and red that could not attributed to a chamber with certainty are indicated. Note that in whorl 6 the alar prolongations of half a whorl cover up to 3/4 of the test. Scale bar is 250 µm. 3D movies of this figure are in the SOM.

Mentions: In most cases chamber shape is obvious and could be reconstructed by selecting the space within the chamber and allowing Avizo to automatically extrapolate the chamber. In rare occasions one of several problems could arise: (1) The chamber is very small, and consists mostly of an alar prolongation (Fig. 1, chamber 88a). Such a chamber was included when it appeared in the virtual equatorial section. (2) The chamber is highly asymmetrical, and has one long and one reduced alar prolongation (Fig. 1, chamber 89). Such a chamber was included when it appeared as a chamber in the virtual equatorial section. Otherwise it was included in the chamber to which it connected. (3) Especially in later whorls, chamber shapes could become complex, and the presence of pillars rendered them discontinuous. In most cases the connections between chambers were obvious, but in rare occasions the law of superposition was used: older chambers are overlain by younger chambers (Fig. 1B). In one specimen (06KW01_05) four lateral parts of chambers could not unambiguously be related to a growth increment with certainty (Fig. 2). Following segmentation the volume of each chambers were calculated using the material statistics option in Avizo 8.1.


Three dimensional reconstructions of Nummulites tests reveal complex chamber shapes.

Renema W, Cotton L - PeerJ (2015)

Chamber shape per whorl in specimen 06KW01_05.Note the increase in complexity of chamber shape. (A) whorl 1; (B) whorl 2; (C) whorl 3; (D) whorl 4; (E) whorl 5; (G) first half of whorl 6; (H) second half of whorl 6. In yellow and red that could not attributed to a chamber with certainty are indicated. Note that in whorl 6 the alar prolongations of half a whorl cover up to 3/4 of the test. Scale bar is 250 µm. 3D movies of this figure are in the SOM.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493699&req=5

fig-2: Chamber shape per whorl in specimen 06KW01_05.Note the increase in complexity of chamber shape. (A) whorl 1; (B) whorl 2; (C) whorl 3; (D) whorl 4; (E) whorl 5; (G) first half of whorl 6; (H) second half of whorl 6. In yellow and red that could not attributed to a chamber with certainty are indicated. Note that in whorl 6 the alar prolongations of half a whorl cover up to 3/4 of the test. Scale bar is 250 µm. 3D movies of this figure are in the SOM.
Mentions: In most cases chamber shape is obvious and could be reconstructed by selecting the space within the chamber and allowing Avizo to automatically extrapolate the chamber. In rare occasions one of several problems could arise: (1) The chamber is very small, and consists mostly of an alar prolongation (Fig. 1, chamber 88a). Such a chamber was included when it appeared in the virtual equatorial section. (2) The chamber is highly asymmetrical, and has one long and one reduced alar prolongation (Fig. 1, chamber 89). Such a chamber was included when it appeared as a chamber in the virtual equatorial section. Otherwise it was included in the chamber to which it connected. (3) Especially in later whorls, chamber shapes could become complex, and the presence of pillars rendered them discontinuous. In most cases the connections between chambers were obvious, but in rare occasions the law of superposition was used: older chambers are overlain by younger chambers (Fig. 1B). In one specimen (06KW01_05) four lateral parts of chambers could not unambiguously be related to a growth increment with certainty (Fig. 2). Following segmentation the volume of each chambers were calculated using the material statistics option in Avizo 8.1.

Bottom Line: During the Paleogene the genus Nummulites was particularly abundant with a global distribution, leading it to be frequently used in biostratigraphy.Here we apply micro computed-tomographical scanning, a tool that recently has become available, to visualise 3D chamber shape of Nummulites djokdjokartae and compare these to traditional morphometrical characters.We argue that 3D reconstructions of Nummulites tests will be a great aid in improving our understanding of lineages within the genus Nummulites, and to elucidate its evolutionary and biogeographical history.

View Article: PubMed Central - HTML - PubMed

Affiliation: Naturalis Biodiversity Center , CR Leiden , The Netherlands.

ABSTRACT
Larger benthic foraminifera (LBF) are important and prolific carbonate producers both in modern and ancient shallow tropical seas. During the Paleogene the genus Nummulites was particularly abundant with a global distribution, leading it to be frequently used in biostratigraphy. However, their evolution is poorly understood as classification is Europe-centered and mostly based on external characters and equatorial thin sections. New occurrences from regions outside the northern Tethys which poorly fit in thus reference frame, show that a more rigid framework for the classification of Nummulites is needed. Here we apply micro computed-tomographical scanning, a tool that recently has become available, to visualise 3D chamber shape of Nummulites djokdjokartae and compare these to traditional morphometrical characters. We find that despite the regular shape in equatorial and axial thin section the irregular 3D chamber shape is not predicted by these sections. We argue that 3D reconstructions of Nummulites tests will be a great aid in improving our understanding of lineages within the genus Nummulites, and to elucidate its evolutionary and biogeographical history.

No MeSH data available.


Related in: MedlinePlus