After the news story a few weeks ago about
the replacement Dippy the Diplodocus at
the Natural History in London with a blue whale skeleton, there has been a lot
of talk in the media and palaeontology community. I'm not going to go into why Dippy should or shouldn't be replaced, as it has been covered by numerous palaeontologists and news sites (for example, palaeontologist Steve Brusatte and HuffPost Technical Editor Michael Randle argue it's a good thing, while others like palaeontologist Mike Taylor disagree with the idea), but I will talk about another thing that has come up since then. One thing that a lot of
non-palaeontologists have been saying is “oh well it was fake anyways” since it
was made up of replica bones rather than real fossils. This is something that really bugs me.
I’m not sure why this has been picked up so
much recently that casts and replicas are just “fake”. First of all, fake is
something that is made with the intent to deceive. Fake money is meant to
replace real money, or fake designer purses are meant to look like the real
ones they imitate so people don’t know you have a fake. A replica or cast of a
fossil is not meant to deceive. That is not the purpose. Any signs about the
specimen will (or at least should) state whether the specimen is a skeleton, cast, or composite. No
one is trying to trick you! You just have to read the signs!
The next important point is how these casts
are made. Fossil casts are made from real fossils. There are many ways of
making them, and I’m no expert so I won’t discuss that here. What I know is
that people who make fossil casts, especially good ones, is that they put A LOT
of effort into making them look as accurate and real as possible. They are most
often made from some kind of mould that is made from the fossil using something
like silicone or rubber. After that, plaster or something else hard is poured
into the mould which allows for the exact structure of the original to be seen.
Finally, the cast is painted and coloured in a way that matches the original
specimen. When done properly and well, these casts look almost identical to the
original fossil and only close examination by experts will reveal it as a cast.
The best cast I have seen was of the pterosaur “Dawndraco” (or Pteranodon
if you prefer) in the American Museum of Natural History (AMNH) pterosaur exhibit that ended in January. Just 2
weeks before I had seen the original at the University of Alberta, and was so
convinced by the cast that I actually emailed the people who made it to confirm
that it was indeed a cast (it wasn’t labeled as a cast, naughty AMNH!). Only
because I knew it was not original was I able to spot the signs, but it was
hard. The important thing to note here is that they are not just “fake” fossils
that are made from someone’s head. These are (usually) skilled professionals
who are basing their model off of a real fossil, and it is meant to look as
close as possible to the original.
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| Original specimen of "Dawndraco kanzai", a pteranodontid from Kansas. Original housed at the University of Alberta |
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| Cast of "Dawndraco kanzai" on display in the pterosaur special exhibit at the American Museum of Natural History |
It's a bit hard to tell from the pictures as the lighting and angle is different, but I can tell you that they looked incredibly similar and the cast looked very real.
The final point to make with this is why museums have casts, especially as
their large centre pieces. There are 2 reasons for this. First of all, fossils
are rare. Despite what you may think by seeing all these fantastic fossils in
museums, they are exceedingly rare. Not every museum has the money to buy a
real fossil, or the ability to go out into the field and dig up their own, so
they have to rely on casts. If not for casts, very few people would be able to
see the specimens. Additionally, if fossils are rare, beautiful, complete fossils that look like Dippy are exceptionally rare. Most often fossils are found with bones
missing, or smashed. Fossil replicas and casts allow for these missing bits to
be filled in from other partial skeletons, which is what we call a composite
skeleton. These can be made from skeletons that are incomplete so some bones
are real, some are not. And of course, when we do find one of those
exceptionally rare complete or near-complete fossils, casts allow us to share them
with the world and show other people. And finally, fossils are of course extremely fragile. It can be very difficult to mount a skeleton in a way that isn't going to damage the specimen, especially if they are fragile. For this reason, museums will sometimes put the cast on display, and keep the original specimen in the collections in order to preserve it. Does it make it any less amazing? Personally, I don't think so. I'd rather know that the original is being conserved and properly looked after than see it on display in a museum.
Fossil casts are not “just a fake”. They
are replicas of rare and uncommon treasures. Without casts, most of the world
would not be able to see these treasures. Dippy, for example, comes from the
Morrison Formation of the USA originally. The likelihood of the Natural History
Museum in London getting it’s hands on a complete skeleton of a large sauropod
from the USA is pretty unlikely. So what would you prefer, no dinosaur at all?
Or an exact replica of a real one that existed on another continent, allowing
you to wonder in awe?
