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Of bones and gizzard stones

October 10, 2008 05:50 by Wayne Gerdtz

 

Better the pebble you know: these rocks will be part of a touchable display about how some dinosaurs used stones in their 'gizzards' to digest their food.

A curator’s desk is a landscape – there are lofty peaks formed by stacks of books, sweeping plains of printed text for labels, and little gullies where biros and pencils congregate. I can’t tidy up this landscape – it would disrupt the ecology of my work as an Exhibition Curator.

Today, some new features appeared on this vista in the form of some bags of rounded pebbles. I suspect I’ll need to explain this a little further – pebble collecting is not a hobby, its part of my job.

In April 2009, the first phase of the redevelopment of the Science and Life Gallery at Melbourne Museum will open to the public. It will be a wonderful experience for the visitor, allowing people to have a unique perspective on skeletons of Dinosaurs, flying reptiles, megafauna and more. One of the unique experiences we want to achieve is to let people use their sense of touch in the exhibition. There are many precious/fragile objects we can’t let them touch, but one of my tasks recently has been to find objects we are happy to say ‘please do touch’. So, I have been thinking of how we could do this, and to source some objects that fit the bill. In a lot of cases, we are encouraging people to feel the teeth of the dinosaurs and their friends, but there’s a problem – some dinosaurs didn’t have teeth.

Toothless (or, if you prefer, ‘edentulous’) dinosaurs obviously needed to find alternative ways to break down their food. We know that at least one group of dinosaurs got around this “can’t chew” conundrum by deliberately swallowing stones that churned around in their bellies, pulverising their food; many birds do this still to this day.

It is these pebbles, called gizzard stones (or gastroliths) that are perched on my desk (sorry, “landscape”) that eventually you will be invited to feel in the new displays, along with a variety of dinosaur teeth and a few other surprises in the new exhibition.

Stay tuned for more, there’s the tale of the ancient fossilised poo coming soon….


Comments

November 14. 2008 10:51

Where were the pebbles obtained? Are they just similar to the ones dinosaurs would have used to digest their food? What sorts of characteristics did the pebbles need to be used for digestion and how did scientists discover that this is what took place? Thankyou

K

November 28. 2008 10:56

Thanks for the questions, K.
The specific pebbles that are in this photo were not obtained from near a dinosaur skeleton, so they are probably not 'real' gizzard stones - these are actually quite difficult to find.
Our gizzard stones are, however, very similar to the real thing in many ways - they have a polished appearance, just as some real gizzard stones would, having been worn down after tumbling around in the dinosaur's digestive tract. Other gastroliths can have a pitted appearance on their surface, evidence of a reaction between the acidic digestive juices of the dinosaur and the chemical composition of the rocks themselves. Interestingly, there's also evidence that marine reptiles in the Mesozoic used pebbles in a different way; they might have used these for ballast, helping them maintain their depth as they swam through the Mesozoic oceans

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