2.  Laminar Structure of Conodonts
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Conodonts were named after the "nested cone" structure of the tooth elements.  Under a light microscope, high magnification images show an intriguing laminar organization that suggests the tooth was created by successively adding new layers to the outside of the tooth as it grew -- like tree rings left by the enlarging bark of a tree trunk.  When damage to the conodont occurred by wear and tear, new layers would rebuild the conodont and enable its continued growth.   It may be possible to obtain some clues about the rate of the conodont's growth by measuring the distance traveled by each growth cone along the axis of growth.  To test this possibility, a large element was photographed by a high resolution mosaic of images, and the triangulated pixel distances from tip to tip of each cone were computed and the rate of growth were graphed, creating the following figures.

Click on Image to view a large 712 KB image of photo mosaic

Conclusion: growth cone spacing shows linear increase in size until a certain point where growth size appears to flatten out and grow less predictable.  However, these spacings are not necessarily correlate to rate of growth, as some portion of the lamina appear to be resorbed or reworked.  For some close-ups of some of the structures, refer to AB02E14.

Page established 7-7-99, updated 7-7-99 -- copyright Jim Davison
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