Wilderness Underfoot: The art of paleontology

StoryImage( ‘/Images/Story//Auto-img-111038560223493.jpg’, ”, ‘Step One – Yes, those are Legos! They make excellent reusable boxes for rubber molds. After a fossil bone has been prepared and sealed, it is placed on modeling clay base within a single-layered frame of Lego blocks. (Shown: a 6-inch long toe bone)’);
StoryImage( ‘/Images/Story//Auto-img-111038562222576.jpg’, ”, ‘Step Two – The clay is built up to cover half of the bone. This will allow for a two-part mold. The exposed half of the bone will be molded first. Little dimples have been pressed into the clay and they’ll help the two halves of the mold interlock when the cast is poured.’);
StoryImage( ‘/Images/Story//Auto-img-111038566023440.jpg’, ”, ‘Step Three – The wall is built up just above the bone. A wood dowel is added between the bone and the edge of the mold; when it comes out, it will leave a pour-spout for casting.’);
StoryImage( ‘/Images/Story//Auto-img-111038568223493.jpg’, ”, ‘Step Four – Silicon rubber is mixed and poured into the Lego box, all the way to the top. It cures overnight. ‘);
StoryImage( ‘/Images/Story//Auto-img-111038570323563.jpg’, ”, ‘Step Five – After the rubber cures, the box is turned upside down. The bottom Lego plate is removed from the box, then the clay is removed. The cured rubber is oiled so it won’t stick to the second pour.’);
StoryImage( ‘/Images/Story//Auto-img-111038572922576.jpg’, ”, ‘Step Six – Silicon rubber is mixed and poured into the space where the clay was. It cures overnight.’);
StoryImage( ‘/Images/Story//Auto-img-111038574923558.jpg’, ”, ‘Step Seven – The Lego box is removed from the rubber. Then the mold is gently separated into its two halves. The bone and the dowel rod come out. Now the two-piece rubber mold can be locked back together, and plastic can be poured into the spout to make sturdy, light-weight copies. ‘);

Many of the dinosaur skeletons displayed in museums are not real…

It really isn’t an attempt to deceive you, but museums often use copies in their displays rather than real fossil skeletons. These reproductions are usually labeled with the word “cast.” Museums have good reasons for displaying reproductions: sometimes the actual fossils are still being studied by scientists, or the fossils may be too large and heavy to put into a mount, or perhaps the original dinosaur is owned by another museum. If a museum can’t display the real dinosaur, the next best thing is to use an accurate reproduction.

The best way to copy fossils is to make rubber molds of them. Using molds, artists can then pour casts and finish-paint them to look so authentic that it is hard to distinguish the casts from real fossils.

Here’s the process that was used to mold most of the bones from Burpee Museum’s Tyrannosaurid dinosaur, “Jane”:

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