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Fossil Study Techniques

DWhatley

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#1
Non-invasive imaging methods applied to neo- and paleo-ontological cephalopod research
R. Hoffmann, J. A. Schultz, R. Schellhorn, E. Rybacki, H. Keupp, S. R. Gerden, R. Lemanis1, S. Zachow 2014 (pdf)

Abstract.
Several non-invasive methods are common practice in natural sciences today. Here we present how they can be applied and contribute to current topics in cephalopod (paleo-) biology. Different methods will be compared in terms of time necessary to acquire the data, amount of data, accuracy/resolution, minimum/maximum size of objects that can be studied, the degree of post-processing needed and availability. The main application of the methods is seen in morphometry and volumetry of cephalopod shells. In particular we present a method for precise buoyancy calculation. Therefore, cephalopod shells were scanned together with different reference bodies, an approach developed in medical sciences. It is necessary to know the volume of the reference bodies, which should have similar absorption properties like the object of interest. Exact volumes can be obtained from surface scanning. Depending on the dimensions of the study object different
 

DWhatley

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#2
Computed reconstruction of spatial ammonoid-shell orientation captured from digitized grinding and landmark data
Susanne Lukeneder, Alexander Lukeneder, Gerhard W. Weber 2013 (full PDF)

Abstract
The internal orientation of fossil mass occurrences can be exploited as useful source of information about their primary depositional conditions. A series of studies, using different kind of fossils, especially those with elongate shape (e.g., elongate gastropods), deal with their orientation and the subsequent reconstruction of the depositional conditions (e.g., paleocurrents, transport mechanisms). However, disk-shaped fossils like planispiral cephalopods or gastropods were used, up to now, with caution for interpreting paleocurrents. Moreover, most studies just deal with the topmost surface of such mass occurrences, due to the easier accessibility. Within this study, a new method for three-dimensional reconstruction of the internal structure of a fossil mass occurrence and the subsequent calculation of its spatial shell orientation is established. A 234 million-year-old (Carnian, Triassic) monospecific mass occurrence of the ammonoid Kasimlarceltites krystyni from the Taurus Mountains in Turkey, embedded in limestone, is used for this pilot study. Therefore, a 150×45×140 mm block of the ammonoid bearing limestone bed has been grinded to 70 slices, with a distance of 2 mm between each slice. By using a semi-automatic region growing algorithm of the 3D-visualization software Amira, ammonoids of a part of this mass occurrence were segmented and a 3D model reconstructed. Landmarks, trigonometric and vector-based calculations were used to compute the diameters and the spatial orientation of each ammonoid. The spatial shell orientation was characterized by dip and dip-direction and aperture direction of the longitudinal axis, as well as by dip and azimuth of an imaginary sagittal-plane through each ammonoid. The exact spatial shell orientation was determined for a sample of 675 ammonoids, and their statistical orientation analyzed (i.e., NW/SE). The study combines classical orientation analysis with modern 3D-visualization techniques, and establishes a novel spatial orientation analyzing method, which can be adapted to any kind of abundant solid matter.
 

DWhatley

Cthulhu
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Sep 4, 2006
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Gainesville, GA
#3
Computed tomography of fossils and sulphide minerals from the Mesozoic of Turkey Alexander Lukeneder, Susanne Lukeneder, Christian Gusenbauer 2014

Abstract
We present a computed tomography and 3D visualisation of Mesozoic cephalopods from the Taurus Mountains. Study objects were single ammonoidsand ammonoid mass-occurrences that were deposited during the Upper Triassic (approx. 234 mya) of SW Turkey. Computed tomography, a nondestructive and non-invasive method, facilitates the view inside rocks and fossils. The combination of computed tomography and palaeontological data enable us to produce 3D reconstructions of the extinct organism. Detailed reconstructions of the fossil cephalopods and the ammonoid animals are based on shell morphologies, adapted from CT data. Object-based combined analyses from computed tomography and various computed 3D facility programmes aid in understanding morphological details as well as their ontogenetic changes in fossil material. The presented CT data demonstrate the wide range of applications and analytical techniques, and furthermore outline possible limitations of computed tomography in earth sciences and palaeontology
 

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