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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

Variation in chamber volumes for three specimens of N. djokdjokartae.(A) specimen 06KW01_19 (shown in Fig. 3); (B) specimen 06KW01_05 (shown in Fig. 2); (C) specimen 06KW01_01.
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fig-8: Variation in chamber volumes for three specimens of N. djokdjokartae.(A) specimen 06KW01_19 (shown in Fig. 3); (B) specimen 06KW01_05 (shown in Fig. 2); (C) specimen 06KW01_01.

Mentions: Chamber shape in equatorial thin section has been related to chamber volume, potentially a more biologically relevant metric to estimate foraminiferal growth (Hohenegger & Briguglio, 2014). Chamber volume of the seven specimens segmented in this study shows a highly irregular pattern that does not compare to previous findings (e.g., Hohenegger & Briguglio, 2014; Briguglio, Hohenegger & Less, 2013). The initial 30–50 chambers hardly increase in volume, followed by a rapid increase in volume of the following chambers (Fig. 8). However in the latter phase occasional small chambers are also formed. These are probably the result of geometric constraints in chamber formation and serve to increase the regularity of the apertural face to facilitate growth in subsequent chambers. In the most comparable study relating growth increment to chamber volume in a complex nummulitids, i.e., the reticulate Nummulites species N. fabianii and N. fichteli, a pattern of stepped growth was identified (Briguglio, Hohenegger & Less, 2013). However, as is apparent in their figures, the alar prolongations, and therefore a substantial part of the chamber volume, were not included by these authors (Briguglio, Hohenegger & Less, 2013).


Three dimensional reconstructions of Nummulites tests reveal complex chamber shapes.

Renema W, Cotton L - PeerJ (2015)

Variation in chamber volumes for three specimens of N. djokdjokartae.(A) specimen 06KW01_19 (shown in Fig. 3); (B) specimen 06KW01_05 (shown in Fig. 2); (C) specimen 06KW01_01.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig-8: Variation in chamber volumes for three specimens of N. djokdjokartae.(A) specimen 06KW01_19 (shown in Fig. 3); (B) specimen 06KW01_05 (shown in Fig. 2); (C) specimen 06KW01_01.
Mentions: Chamber shape in equatorial thin section has been related to chamber volume, potentially a more biologically relevant metric to estimate foraminiferal growth (Hohenegger & Briguglio, 2014). Chamber volume of the seven specimens segmented in this study shows a highly irregular pattern that does not compare to previous findings (e.g., Hohenegger & Briguglio, 2014; Briguglio, Hohenegger & Less, 2013). The initial 30–50 chambers hardly increase in volume, followed by a rapid increase in volume of the following chambers (Fig. 8). However in the latter phase occasional small chambers are also formed. These are probably the result of geometric constraints in chamber formation and serve to increase the regularity of the apertural face to facilitate growth in subsequent chambers. In the most comparable study relating growth increment to chamber volume in a complex nummulitids, i.e., the reticulate Nummulites species N. fabianii and N. fichteli, a pattern of stepped growth was identified (Briguglio, Hohenegger & Less, 2013). However, as is apparent in their figures, the alar prolongations, and therefore a substantial part of the chamber volume, were not included by these authors (Briguglio, Hohenegger & Less, 2013).

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