4.2 Thrinaxodon - Fossil

4.2.1 Background

Thrinaxodon - A late Permian mammal-like reptile that was coming very close to being a mammal. It was a carnivorous little creature that would have grown to about the size of a small dog. Its needle-sharp teeth are classic indications of its meat diet, being present in even the smallest (youngest) of specimens. It has been suggested that Thrinaxodon was an insect-eater as well as a scavenger and a hunter of smaller animals. This interesting animal was a burrower; many fossils have been found of Thrinaxodon that died in their sleep when their tunnels obviously collapsed on them. There is disagreement between South African and American scientists about reconstructionís of Thrinaxodon. Americans persist in putting fur on them, while South African scientists are adamant that fur had not evolved as a body covering 230-million years ago when these creatures were running around. American scientists have also speculated that Thrinaxodon were territorial animals that scent-marked their territories. Pronunciation guide: Thrinaxodon (Thry-NAKS-oh-don). Both Lystrosaurus and Thrinaxodon are creatures that inhabited the ancient Karoo area of South Africa. [15]

A plastic resin print was made from the original fossil. A great deal of rock was still inside the fossil. This rock is in general not removed as it is too difficult and not easily accessible. The resin fossil was CAT scanned at Krugersdorp Private Hospital. The data was retrieved and converted according to the procedure earlier mentioned.

This particular case study was a real treat. The data was converted with great ease in a very short period. The next stage, converting into 3D imaging was also rapid and effortless. A 3D model was created and a STL model was exported with the aid of the Materialise CTM software.

The STL file was imported into the QuickSlice software and processed. The processing took place on a Silicon Graphics Indy computer, called INDY1. The data processing failed miserably, after two chances. The computer just could not manage the large data files. The Quick Slice software was installed on the Silicon Graphics O2 computer, called LANCRE. Various grow parameters were selected and the processing was started again. This computer processed successfully, generating the horizontal slice, SSL file as well as the machine language, SML file. The SML file was then transferred, via our LAN with the aid of FTP, to INDY1 as it was connected directly to the FDM machines. The prototype was removed from the working envelope and the support structure was removed and cleaned.

4.2.2 Conclusion

This is the ideal method for capturing complex, low tolerance and detailed geometry. A FDM prototype was grown to verify the process. The RE method was used to get the data in an electronic format so that it can be used in other processes. Images





The Thrinaxodon Fossil (grey) and FDM Prototype (red)


The Thrinaxodon

3D Reconstruction of CAT scanned fossil
3D Reconstruction of CAT scanned fossil

3D Reconstruction of CAT scanned fossil
3D Reconstruction of CAT scanned fossil


4.2.3 Thrinaxodon Data Sheet:
  Description Options (Default) Data


1 CT Image Names   bpi2.001
2 Patient/Project Name   bpi2.pat
3 Number of First Input Image   1
4 Number of Last Input Image   99
5 Number of First Output Image   000
7 Horisontal Nr. Of Image Pixels 0 to 65535 (265,512,1024) 512
8 Vertical Nr. Of Image Pixels 0 to 65535 (265,512,1024) 512
9 Number of Images per File (1) 1
10 File Swap Format (0,3) 0,3 CCELSC
11 Pixel Type B,UB,S,US,L,UL,F -
12 Header Size *see formula below -
13 Inter Image Header Size 0 -
14 Add Value 0 to 4095 -
15 Scale Value 0 to 4095 -
16 Table Position (mm) 0
17 Distance Between Slices (mm) 1
18 Slice thickness (mm) 1.2
19 Pixel Size SQ. F.O.R./Nr. Hor. Pixels (mm) 0.47
20 Gantry Tilt Angle Degrees 0
21 Field of Reconstruction/View (mm) 240
22 Number of Images   99
23 File Size of CAT Image kb 75
24 File Size of Converted Image kb 60
25 .3dd file size Mb 25
26 .STL file size Mb 26.75
28 .IGS file size Mb -
29 RP Slice file size Mb 9
30 RP Download File size Mb 10.8
31 Grow Time Hour 41.4
32 Tip size (T12, T25) T12
33 Slice Thickness (0.01", 0.014") 0.01"
34 Finishing Time Hour 4
35 Processing Time Hour 2
36 Data Retrieval Time Hour 4
37 Total Cost Rand =41.4*100+6*150+4*55+500



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