Analysis of Mistakes Corrected and Perpetuated

ANALYSIS OF MISTAKES CORRECTED AND PERPETUATED IN MULTIPLE MOUNTS OF PLACERIAS GIGAS AND RESIN CAST CONSERVATION PROBLEMS.
(Original presentation at SVP in 1996, re-presented at this meeting because of immediate relevance)

Reser, P.K., Retired
Box 67636
Albuquerque, NM 87193
and
Geiser, R.M., Retired
605 Adaline St.
Carson City, NV 89703

Late in '87 our museum delivered a mount of Placerias to Petrified Forest National Monument (since, National Park) Arizona. It was then moved several times and altered by third parties. It also suffered from ultraviolet degradation and temperature extremes because it was placed behind unfiltered windows. These factors exacerbated the original fabrication, anatomical, and materials flaws. Mounts are composites of materials but also of real and restored bone parts from different individuals, and current scientific opinion. Anomalies are certain and only resolvable by the process of fitting together the whole three-dimensional animal.

In September of '91 we completed another mount for ourselves (New Mexico Museum Of Natural History And Science) articulated at one extreme of the range of movement of the vertebral column. This configuration changed our concept of Dicynodont posture but also repeated distortions of the pectoral girdle originally introduced by ribs restored in an arc too wide to allow the sternum to articulate with the scapula-coracoids.

This year ('96) a corrective overhaul of the first mount (existing mount at Petrified Forest) was undertaken. We found serious delamination between the W.E.P. cast material and adhesives, fillers, and paint except where filled polyester resin (Bondo) was used. We found that rib restorations had to be re-contoured, the the restoration of the proximal humeri prevents assumption of the posture seen in the standard published figure, the feet are probably mis-interpreted, and no fossil mount is 100% accurate.

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Last updated: March 16, 2018

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