Isn’t it true that most, if not all, of the big dinosaur skeletons on display in museums are just casts made from the actual fossils?
I’ve heard that they use casts because the actual fossils are too heavy to mount, but that sounds like a wimpy excuse. Regardless of the reason, it seems to deflate all the wonder of seeing dinosaur bones. If it’s just a hunk of plaster molded to look like a fossil, what’s the big deal? Might as well show me a picture. But if it were the actual fossilized bones from a gazillion years ago, that would be pretty cool.
There’s a new one going on display here in Atlanta, and it’s supposed to be a big deal specimen of some ferocious dinosaur. But it turns out the thing is plaster; the real bones are back in the lab somewhere.
– Greg, Atlanta
There are several reasons why plaster casts are used in place of fossil bones (as an aside, I just reminded myself of the inspiriation of the KISS song “Plaster Caster” funny stuff).
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Fossils are VERY rare. Really rare. For instance, you have many times over more “Natural History” museums than you have T. Rex skeletons. What to do? Just make molds of the ones you have to show what a T. Rex really looks like.
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Complete skeletons are even rarer. They just discovered the first nearly (>90%) complete T. Rex skeleton a few years ago, and it (the actual fossils) is on display at The Field Museum in Chicago. A recreation is on display at Animal Kingdom in Orlando. Most often, scientists have skeletons from several individuals, but no complete skeletons, and so a composite must be made. Plus, sometimes there are no bones of a certain type, and one must make educated guesses (albeit VERY informed guesses) as to what those bones look like.
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Contrary to popular belief, many fossils are quite fragile, and could not stand up to diplay. It all depends on what sort of stuff the fossil is made of. There are lots of fossils that collapse under their own weight, never mind the weight of an entire skeletal display.
Hope that clears stuff up!
Not only that, but in order to mount a skeleton you usually have to drill into the fossil. This destroys part of it – the interior structure of the bone is usually fossilized, too, after all. It’s much better to make a cast and mount IT, then keep the undestroyed original for study.
For many years the only nearly complete T. Rex skeleton was the one in the American Museum of Natural History. The skull on the mounted skeleton was always a cast – the original was kept on display in a case near the floor. You can see why. Why take the chance – however slim – of the world’s only T. Rex skull falling from its precarious perch high above the ground? (By the way, “Sue” and other recently discovered T. Rex skeletons have gorgeous skulls. The AMNH skull was crushed and distorted during fossilization. Sue’s head is wonderfully symmetrical, and the owners know it – the mounted skeletons and casts are positioned so you get a good view of that symmetrical skull.)
<< Plus, sometimes there are no bones of a certain type … >>
Such as the intercostal clavicle.
Katherine Hepburn: “But, David, now that they know where to find them, couldn’t they just go look there again?” [/obscure reference]
I saw that movie just last week. I still get a kick out of Cary Grant holding what looks like a cow’s femur and wondering aloud if it goes in the tail.
I think a 3D life-sized representation is much more interesting than a small 2D photo.
I can’t give you anything but love, baby . . . .
Good explanations for why they use casts, but it still takes a lot of punch out of seeing one when you know it’s not the real thing. If it’s just a cast, they could make a hundred of them and have the same dinosaur all over the country.
And I think a lot of museums just conveniently let the public assume they’re the real bones. Nobody trumpets that they’re getting a plaster cast of some bones; they put up billboards screaming about the new dinosaur in town.
– Greg, Atlanta
I can’t think of the title, but it was somthing with the word “baby” in it, and it a panther or other big cat was in it. It was a -great- movie though. My X-SO made me watch it, and I really enjoyed it- she had good taste in movies. Anyone know the title?
I was just reading about the display arangements for ‘Sue’ the nearly complete T. Rex in Chicago. In her case, what you are seeing is, in fact, the real fossilized skeleton. The mounting structure is specially designed to hold each piece in place without drilled holes or other damage.
The only major bit of fakery is the skull. As others have mentioned, the real skull is too heavy and too valuable to place on that high perch. Instead, a cast is resting on Sue’s shoulders and the real skull is on display at human-eye level. An acceptable trade-off I think, considering the close-up view it will give you and I that we wouldn’t have otherwise.
Using a ‘fake’ also allows the folks in Chicago to ‘undistort’ Sue’s skull for display purposes. According to the article, very few large dinosaur skulls are discovered undistorted by the enormous geologic pressures that are applied to them over the millions of years it takes to fossilize. The cast skull has been manipulated to remove most of the distortions, something they couldn’t do to the real skull for fear of destroying delicate structures. Also, seeing the real, un-corrected skull beside the fake, though lifelike mounted skull, should present an interesting and useful contrast.
And finally, please explain to me how, and for that sake why, a small dog could carry around a fossilized dinosaur bone. It’s a wee bit heavy for Fido and sure doesn’t taste like much of anything except for what it is… a rock! Sorry, but I groan everytime I see that scene.
Oh, and it’s “Bringing Up Baby”, BTW. Howard Hawkes, 1938, Kate Hepburn, Cary Grant - the archetype of the ‘screwball comedy.’
Great movie in almost every respect, but I cringe everytime I see the poor mutt that’s supposed to be carrying around the 100 pound rock shaped bone.
Another nice point to casts is that they can let people touch them (or at least not worry about people touching them). The Chicago Field Museum has several “fossils” on display with big signs inviting you to touch the tricerotops (sp?) skull since it’s a fake. Not only does it look just like the real thing, but you can have your girlfriend take your picture with your arm shoved in its mouth.
Incidentally, I was there one time and joking stuck my arm in its mouth and said “aahh… it’s eating me” and some museum woman walked up to me and said “Oh, no… it was a plant eater. It wouldn’t ever bite you” as if I was six years old. So I said “What if I poked it in the eye with a stick?” to which she said “Well, I guess it might bite you then.” I think that woman spent a little too much time in museum country 
Quoth dwtno:
Actually, the public could get a good close-up view of the mounted skull-- I was in Chicago a year ago (yeah, I know, but it was a business trip… I couldn’t get them to reschedule the AAS meeting), and they had displays showing where they were going to mount it. There’s a balcony right at head-level, and they were planning on putting it within a few feet. All of this may have changed in subsequent planning, of course.