6.1 Collecting and processing

There are two major difficulties with regard to successing in yielding Orsten-type fossils: 1) the discovery of suitable rock in the field and 2) the picking and sorting quality. Many underestimate particularly the latter aspect, which requires a very good microscope and skills in recognizing the specimens – and organiszed working. Sloppy documentation, for example, is a catastrophy.

1) Discovery: Recognition of phosphatized fossils on or in the rock in the field is impossible due to their size. The only exception are the shields of phosphatocopines, which may be discovered on some of the nodules. Klaus had found them and this was one of the characteristics of a rock to select and etch it. Another aspects are the colour and the size of the crystallites. The numerous calcified Agnostus-pisiformis shields are, however, no indicator, although Klaus and his assistants had uncovered more than a hundred phosphatized young stages of it. For example, Dieter once collected 'Orsten' nodules from a road cut, but all were just "empty".

Another thing we known know is that limestones having yielded 'Orsten'-type fossils are not necessarily nodular like those from Sweden. The material from Siberia is not nodular but layered, more crust-like.

2) Processing: After some cleaning from recent dirt and contamination, the rock is crunched to pieces and out into a sieve with a mesh size of about 200µm mesh size. Another one with a mesh size of 100 or 50 µm is put underneath. These are placed in a 10-l bucket and covered with water containing 10% acetic acid. Buffering may be done, but is not really necessary due to the amount of calcium. After about 10-14 days, the residues are rinsed and dried and put into bottles.

3) Selecting: The sorting process under a binocular microscope is time-comsuming and should be done very carefully by skilled persons. People not trained in differentiated viewing will not find much under the microscope. Again, Klaus Müller has selected very special, handmade ZEISS microscopes for this, which he still thinks are not only the best, but the only instruments to yield the 'Orsten' material.

The fossil fragments are spread into a flat rectangular bowl with a grid on the surface and sorted out using a fine brush. Each wanted fossil is swept into a Franke cell, which is placed underneath the sorting plate in a kind of carrier, which has a hole in the center. The unwanted rest can be stored in a corner. Grid quare by grid square is searched through and emptied until the surface is clean except the corner with the remains. These are put into a second bottle. Slowly, the original residue bottle is emptied and and portion by portion looked through. Eventually the remains are put back into the numbered residue bottle.

The next step is a detailed check of the Franke cells for 3D fossils rather than small shellies and conodonts (if they haven't remained in the remains already). Both these elements are also phosphatized and interesting, but were not the direct scope of our 'Orsten' research. The material may also contain other phosphatized fossils such as brachiopod shells and also sponge spicules (secondarily changed into phosphate or primarily silicified).

At this light microscopy stage of processing the material, we cannot identify if fossils are well preserved. They are not only tiny, but shiny and appear to look nice. Details cannot be seen very well. Yet, as you may see from the image on the right side, there the ventral details body and limbs are ill-preserved, and only the soft membrane, inner lamella, that spans between out shield rim and body appears nice. Therefore, investigations are restricted, therefore, to scanning electron microscopy – "our eye", so to speak.

6.2 Scanning Electron Microscopy (SEM)

SEM work is not only our major work tool, but it is our "eye" to view on these extremely tiny critters. Even more, it is the only method to visualize the material. Light microscopy yields no results at all. One can see specimens, which are brownish and shiny, but details cannot be seen.

The specimens are monitored starting with overview magnifications of 20-100 and then going into detail even up to 10.000 times magnification. At this magnification the granular phosphatic surface contrast and resolution hinder nice views, but finest pores of 1-2 µm or setulae of 0.2-03 µm in diameter can be documented.

SEM also allows to tilt and by this to create a series of shots at different angles. Combined, one yields a, more or less, smoothely running movie. You can see an example on the "running projects" page, andother on the page "finished projects", and here's another one of Agnostus pisiformis. The head shield is missing so that one views into the turning trunk shield with some trunk limbs preserved.

The Center of Electron Microscopy has built a special tilting and rotation unit for us, which permits tilting of 90 degrees. This helps us much in re-scanning old specimens of which we have only overviews.

More soon.

6.3 An easy way of producing stereo images

Various of our animals have also been photographed using the SEM for stereo images. The images are in greys, but they can be used to produce nice stereos. An easy way for presentation without special lenses, just putting red-green glasses on, is explained here. Klick on the example picture on the right to access our stereo page:

6.4 3D reconstructions/3D modelling

1. Clay models

Already in 1987 Dieter had started to use 3D modelling as an addition to his drawings and also to facilitate interaction with his illustrator in Bonn. The first paper, in which this was presented was the work on Bredocaris admirabilis. In this paper Klaus and Dieter show a plasticine model Dieter had created. It was 40 cm large and a half model. This could be used to make not only nice shots and even macro photographs (e.g. of the mouth area) but also to produce serial images by progressively changing the orientation of limbs, so simulating movements. And by combination of tilted images it was possible to produce complete views even of oblique angles.

2. Line drawings and computer-generated reconstructions

Our reconstructions of 'Orsten' anumals were first handdrawn and finally inked. This was the standard procedure in documentive biology in the good old days. Dieter's skills were actually one of the reasons for Klaus to take him as an assistant.

Much later, we also tried to adopt different computer programs, mainly graphic programs. Scanned handdrawings were modified, re-assembled, cleaned, and re-drawn, etc., more or less, a mixed technique. Complete drawings made in an illustration program was and is still rather time-consuming; often the result looks "stiff" and artificial.

Yicaris dianensis is one of the taxa drawn completely in Adobe Illustrator.

More about the history and techniques of making such illustrations in due course.

3. Using the software Blender

The Oelandocaris model formed the idea of applying 3d computer software. Martin was the first, and he developed a model of Oelandocaris using the 3D software Blender, an open-source program freely available from the internet. Martin even animated the fossil eventually. Enjoy Oeli swimming here!

Joachim was the next in our team in learning to use this mighty program. So far, his effort resulted in the production of whole series of larvae, e.g., of Goticaris, Cambropachycope and Henningsmoenicaris, also in a model of the living water flea Bythotrephes, and much more – including stereo images in green-red more many of our animals.

Below you can find a few more explanations that might encourage the one or other to try this program himself or herself:

You can follow this link and learn how Joachim and Martin have produced reconstructions of various of our Orsten fossils with the aid of the 3D software Blender, an open-source program freely available on the internet. The page is still under construction and will be filled bit by bit. Images and example movies are already there or on other pages.

4D Modelling

The next step Joachim proceded to go was the creation of 4D modelling, which he understands as the reconstruction of a larval sequence in 3D, so 3D through time (of an animal). As an example, the different stages of Henningsmoenicaris scutula are shown on the righ, from the smallest stage with initial mouth onward to the largest that we could reconstruct having stalked eyes. See more here.

7. Aspects/Questions to be worked up in the future:

• Details of phosphatisation and aspects of 3D preservation
  
  
• Small size matters: Why is only small stuff being preserved?
  
  
• Details on other localities having yielded 'Orsten'-type preservation, such as Comley, UK, and China
  
  
• Geological setting and palaeoecology of the 'Orsten'
  
  
• The Cambrian system as a whole.