Roubach et al., 2014: PREPARATION OF TURTLE FOSSIL
Figure 5: 3D scan; A-B): superior part; C): inferior part.
3D scan
Silicon mould
Due to the lack of a satisfying permanent and
However, 3D scanning with the current
reversible procedure which would maintain the
technology lacks some precision compared to
articulation of the specimen, it was decided to
moulds in the angled regions of the fossil (e.g.
dislocate the bone phalanges after the
phalanges and between the cranium and the
preparation process. Hence, for the first time at
carapace).
In
order
to
record
this
the Camp dels Ninots site, a 3D scan was
morphological information, a silicon mould was
carried out in order to document the original
also made using a two part poured mould with
state of the fossil before the separation of the
plaster jacket (mother mould) method (Smith
small bones (phalanges). A Breuckmann
and Latimer, 1989; David and Desclaux, 1992).
smartSCAN 3D-HE mounted with a 250mm FOV
First,
the
plaster
jacket
had
to
be
was used to create a 3D model of the turtle
manufactured. Protected by a plastic film, the
fossil, and the obtained mesh was processed
fossil was covered with plasticine in order to
using
Breuckmann
Optocat
2012R2
and
follow the fossil shape without flattening it too
Geomagic Studio 2013 software packages. The
much on the bone. Two posts of plasticine were
data points acquired were more than 3.5 million
constructed in the top part and joined by
triangles for each surface of the fossil,
plasticine bands, and small keys were also
corresponding
to
a
resolution
of
4729
constructed around the fossil. To avoid the
points/cm2/cm, equivalent to ca. 0.14 mm
coating of plaster in plasticine, a layer of
spacing between points. It is noteworthy that
Vaseline was applied with brush. Then, a
the resolution is reduced in (Figures 5A, 5B) for
mixture of plaster-water was applied to form
visualization purposes.
the jacket. Once the plaster got dry,
the support, plasticine and plastic film were
43
Journal of Paleontological Techniques