[coccoliths] morphometrics for 3D printing

[Fabrice MINOLETTI]

Hi Jeremy, 
Many many thanks for the tips! 
>>> responses below 
Best, 
Fab. 



Hi Fab 
Nice model! I'm not too sure you will find much of that sort of data but: 

1. Braaudosphaera can be modelled entirely mathematically so could be a nice place to start. 
>>> 1. Indeed Braarudosphaera is a good choice, along with "simple" Pg nannoliths (fasciculithus, rosette discoasters, etc). Neogene curvy discoasters will be technically more difficult I think along with Helico and all ornamented coccoliths. 
>>> We aim at the Noelaerhabdaceae lineage (first step = reticulofenestra, and the gephyros by adding bridge elements at different angles and E/G hux by adding slits) 
>>> Beyond the platic model (which is fun and appealing in a structural geology dept!) the objective is to make students understand which part of the coccos is variable (bridges, bars, slits, ecc) and which part is similar between taxa (basically a flat surface tilted and rotated n times, and then horizontally squeezed to make an oval). 
Indirectly its the V/R model. 

2. In the particular case of the C. lept distal shield the faces are all rhombohedral calcite a faces so you can derive most of the angles simply from that - but maybe that is what you have done already? Two references for this are Young et al 2004 and Avrahami et al 2022 
>>>I will check these refs. 

3. In a way what you are doing is similar to what I did ages ago in 2-D - see Young 1989. 
>>> I thought about Xray nanotomography papers but missed this (early Anthropocene) ref. I also had a look at the rotating nannofossils page on the ina.tmsoc website but it was difficult to properly make measurement (the models are very nice but… they rotate) 

If the CAD program is able to eliminate the parts of two solids which overlap 
>>> The soft can do that (= the "difference()" command) 
then I guess you mostly need to define the leading edge of each element and the profile across the coccolith 
>>> Good idea but the result will be a flat distal shield surface, without the small steps between crystals. 
>>> Anyhow, we will give it a try. 

Jeremy 

Avrahami, E. M., Houben, L., Aram, L. & Gal, A. (2022). Complex morphologies of biogenic crystals emerge from anisotropic growth of symmetry-related facets. Science. 376 : 312-316. 
Young, J. R., Henriksen, K. & Probert, I. (2004). Structure and morphogenesis of the coccoliths of the CODENET species. In , Thierstein, H. R. & Young, J. R. (eds) Coccolithophores - From molecular processes to global impact. Springer, Berlin 191-216. 
Y Young, J. R. (1989). Observations on heterococcolith rim structure and its relationship to developmental processes. In , Crux, J. A. & van Heck, S. E. (eds) Nannofossils and their applications: Proceedings of the 2nd INA Conference, London 1987. British Micropalaeontological Society Publication Series . 1-20. 




On 12 Oct 2023, at 16:39, Fabrice MINOLETTI <fabrice.minoletti at sorbonne-universite.fr> wrote: 



⚠ Caution: External sender 

Dear all, 

I'm working with (geo)student of the FabLab here in Paris. 
Their objective is to construct 3D models of coccoliths for teaching purpose. 
These models are made with OpenSCad and use simple volumes (squares, cylinders, polygons) and simple operations (rotation, translation, ecc). 
The downside of this approach is that we need quantified morphological parameters as dimensions and angles of the crystal elements. 
Attached are some images of a preliminary test on C.leptoporus to validate the approach. Coccolith interlock quite well to form a full coccosphere. 

Does anyone know were we can find such morphological data? 
For example: angle of kinks, angle between distal shield elements and the plane of coccolith, space between proximal and distal shield, width of tube elements, ecc, ecc 

Do such data even exist? 

Thank you in advance for any help! 

All the Best, 
Fabrice. 


- - - - - - - - - - - - - - - - - - 
Fabrice MINOLETTI, PhD 
Maître de Conférences HDR – Sorbonne Université 
Institut des Sciences de la Terre de Paris (ISTeP - UMR 7193) 
Campus Pierre et Marie CURIE, Paris, France 


- - - - - - - - - - - - - - - - - - 
Fabrice MINOLETTI, PhD 
Maître de Conférences HDR – Sorbonne Université 
Directeur Master STePE Portail SDUEE 
Co-responsable Parcours-type Géosciences et Planétologie (GEO-P) 
Institut des Sciences de la Terre de Paris (ISTeP - UMR 7193) 
Equipe Terre/Mer: Structure et Archive 
Campus Pierre et Marie CURIE 
T56-55 5eme - Case 116 - 4, Place Jussieu 75252 Paris cedex 05 
Tel: +33 (0)1 44 27 27 60 
Site Web http://www.istep.upmc.fr 
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