Shark vertebral centra show no histological evidence of resorption at any time in the animals' life.
Deorganification of centra always reveals a large, residual, stable, three-dimensional skeleton. In
contrast, the mineralized parts of other organs (e.g. claspers and jaws) crumble into their individual
mineralized subunits, the tesserae, upon deorganification. In both cases, only appositional growth of
cartilage on the pre-existing mineralized template is possible. The basic 'double-cone' shape of the
vertebrae facilitates increases in body length simultaneously with an accompanying increase in girth.
Once the initial shape of the mineralized portion of a vertebral centrum is fully established and hence
can be described, then relatively simple mathematical models might be devised to predict future growth
patterns. To advance this hypothesis, it has first been necessary to develop a method that can accurately
record the sizes and shapes of complex three-dimensional anatomical structures. This paper describes
a technique that is capable not only of recording and measuring the size and shape of shark vertebrae
but also of predicting their subsequent growth. Furthermore, the technique enables reproduction of
three-dimensional coloured and shaded stereoscopic images of vertebral structures, facilitating a better
understanding of their intricate morphology. Three-dimensional coordinate data gathered from any
shark vertebra can be manipulated mathematically to model future vertebral growth. Producing realistic
images of vertebrae transformed in this way may allow the exploration of possibly unrealized taxonomic
affinities.
A STUDY OF THE NEW ROAD SURFACE EVALUATION METHOD USING THREE-DIMENSIONAL COORDINATE DATA
