Abstract Detail

Paleobotanical Section

Gee, Carole T. [1].

Applying micro CT and 3D visualization to silicified cones from the Late Jurassic Morrison Formation, USA: a virtual advantage over thin-sectioning.

Because of the relative rarity of reproductive organs in the fossil record, the use of microcomputed tomography (micro CT) and 3D visualization was explored as a nondestructive method of eludidating and imaging the internal tissues of 150 million year old conifer seed cones. This offers an alternative to the conventional method of thin-sectioning, which destroys fossil material irrevocably. The 150 million year old cones were discovered in the Late Jurassic Morrison Formation of Utah, which has yielded one of the most prolific dinosaur faunas in the world. The cones are silicified, bear seeds, and can be sorted into nine morphotypes that differ from one another in gross morphology, e.g., size, shape, and surface details. However, in these ancient conifers, as well as in many conifers today, understanding the internal structure of the seed cone is crucial for identification and differentiation between taxa. Thus, it is essential to be able to study the internal details of the seed cones to understand their biological affinity. If the tissues within the fossil seed cones are preserved in differing densities, micro CT will produce transverse and longitudinal sections through silicified cones that show important internal characters easily, accurately, efficiently,and completely nondestructively. These characters include phyllotaxy of the seeds and cone scales, vascularization, shape of the cone axis, and number of seeds per cone scale. The use of micro CT on recent seed cones is even more effective. A preliminary survey of the Pinaceae indicates that pinaceous cones always bear three rows of seeds, each of which spirals many times around the cone. In fossil and recent Araucariaceae, however, the seed cones seem to have a completely different bauplan in which each cone has many more seed rows (up to 21) that wrap around the cone in a complete turn (360 degrees), half a turn (180 degrees), or not at all (0 degrees, resulting in a steep seed row from cone base to distal tip, parallel to the cone axis). Color segmentation, or the addition of artifical colors to selected tissues, aids in the effective visualization of the seed cone in three dimensions and especially of the internal tissues of the cone. Applying micro CT to fossil conifer cones, as well as to recent cones, coupled with 3D visualization, is proving to be a revolutionary technique that can produce excellent sections and images of fossil plant reproductive organs without cutting or damage.

Broader Impacts:

1 - University of Bonn, Steinmann Institute, Division of Paleontology, Nussallee 8, Bonn, 53115, Germany

Keywords:
Micro CT
3D visualization
fossil
conifer seed cones
Pinaceae
Araucariaceae
Late Jurassic
Morrison Formation.

Presentation Type: Oral Paper:Papers for Sections
Session: 16
Location: Melrose/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 8:30 AM
Number: 16002
Abstract ID:109
Candidate for Awards:None