Tuesday, May 24, 2011
Terrestrial plant and animal life was in its evolutionary infancy and most of the planet's biota was aquatic. Unlike today, vertebrates occupied a relatively lowly position in the food chain, which was dominated by large predatory invertebrates. To compensate for this, early vertebrates often had hard, bony armour covering all or part of their bodies. In Tremataspis this armour was confined to the head, which was completely encased in bone - the animal peered out at a hostile world through a hole on top of its head, the biological equivalent of a view-port in a tank. It's this head shield that gets preserved in the fossil record - if you click on the photo, you can see the view port and imagine a small pair of eyes staring out at you (OK, maybe not the last bit, unless you have a very overactive imagination). On the underside is a small mouth that has no jaws - Tremataspis and its relatives diverged from the "main" path of vertebrate evolution before jaws evolved (from modified gill arches). It is, to our eyes, a deeply weird animal. But it's also a distant relative of ours - part of our (very extended) family tree.
We'd like to use Tremataspis to help show visitors that the world of 420 million years ago was a very different place, as part of the wider story of our changing planet that will be told by the new fossil galleries at the Peabody. And this is a great fossil of Tremataspis. The problem is that it's tiny - not much bigger than my thumbnail. Viewed quickly, it looks - dare I whisper it? - a little unimpressive. When we were first evaluating fossils for the exhibit, working from photos, we discarded all of the Silurian vertebrates as being unworthy of display. It was only when I went back into the collections to look at the fossils myself that I realized just how stunning this little guy is. The challenge is how to get people to appreciate this when Tremataspis has to share a gallery with multi-ton bruisers like Apatosaurus, Stegosaurus, and Triceratops.
It's one of the many paradoxes of paleontology that some of the most important material we have is also some of the least impressive to look at. It's easy for the public to understand why someone could spend a lifetime studying T. rex; it's less easy to understand why another paleontologist might spend decades sieving the sediment from around a T. rex in search of microscopic mammal teeth. But I'm guessing that for many paleontologists, the discovery of the first Cretaceous primate would far exceed the importance of another tyrannosaur. Well, I'd think it was more important. The old maxim that size isn't everything is never so true as when it's applied to paleontology and this is another message that we'd like to get across through our displays.
Historically, museums have adopted various strategies to try to get the public interested in visually unimpressive specimens. Models are one possible solution; artwork another. But one needs to be careful. As a child, I was convinced that the Natural History Museum in London was the owner of a stuffed dodo. As I later discovered, of course, the "dodo" was actually a Rowland Ward model made from plaster and goose feathers. The actual "most complete dodo," which resides in Oxford, is an infinitely more important specimen and very moving - when, after some years working there, I finally got to hold the skull with its withered skin and feather stubs I had a "moment" - a rare occurrence for me (as the regular reader will know, I tend to take a very unemotive view of the material I look after). We did eventually add a model (and a composite skeleton) to the Oxford exhibit, but the more I look back on this, the more I wonder whether we didn't end up disrespecting the actual specimen.
One solution that we've discussed is to treat these tiny fossils like the jewels they are - use a combination of spotlighting and a tiny specimen in a large case to draw the visitor in. Another is to use a bigger fossil as a hook. Placing Tremataspis alongside an 8 foot long predatory arthropod from the same period makes a powerful statement about a world that was so different that our distant ancestors were menaced by something that today we'd probably make into Thermidor.