Classical and new bioerosion trace fossils in Cretaceous belemnite guards characterised via micro-CT
The ongoing technical revolution in non-destructive 3-D visualisation via micro-computed tomography (micro-CT) finds a valuable application in the studies of bioerosion trace fossils, since their three-dimensional architecture is hidden within hard substrates. This technique, in concert with adv...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Pensoft Publishers
2017-07-01
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| Series: | Fossil Record |
| Online Access: | https://www.foss-rec.net/20/173/2017/fr-20-173-2017.pdf |
| Summary: | The ongoing technical revolution in non-destructive
3-D visualisation via micro-computed tomography (micro-CT) finds a valuable
application in the studies of bioerosion trace fossils, since their
three-dimensional architecture is hidden within hard substrates. This
technique, in concert with advanced segmentation algorithms, allows a
detailed visualisation and targeted morphometric analyses even of those
bioerosion traces that are otherwise inaccessible to the widely applied
cast-embedding technique, because they either are filled with lithified
sediment or cement
or are preserved in inherently insoluble or silicified
host substrates, or because they are established type material and should
not be altered.
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In the present contribution selected examples of such cases are illustrated
by reference to bioerosion trace fossils preserved in Late Cretaceous
belemnite guards from the European Chalk Province. These case studies
comprise an analysis of a diverse ichno-assemblage found associated with the
lectotype of the microboring <span style="" class="text"><i>Dendrina dendrina</i></span> (Morris, 1851) in a belemnite from the upper
Campanian to lower Maastrichtian chalk of Norfolk, England, and the
description of two new bioerosion trace fossils with type specimens found in
belemnite guards from the lower Campanian limestones of Höver, Germany.
The latter are <i>Lapispecus hastatus</i> isp. n., a tubular and occasionally branched macroboring for
which a sipunculan or a phoronid trace maker are discussed, and <i>Entobia colaria</i> isp. n., a
camerate network formed by an excavating sponge that eroded diagnostic
grated apertures at the locations of the presumed inhalant papillae or
exhaling pores, adding to or replacing filtering devices that are otherwise
made of tissue and spicules.
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As an added value to the non-destructive visualisation procedure, the
processed X-ray micro-CT scans of the studied type material provide
3-D models that may now serve as digitypes that can be studied as digital
facsimile without the necessity of consulting the actual type specimens. |
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| ISSN: | 2193-0066 2193-0074 |