Based in Mahone Bay, nova scotia, agile libre is an independent publisher of technical books about the subsurface.  

Into the mouth of the mouse

I was nearing graduation and eating lunch in the canteen of our institute with my supervisor, who at that time was getting close to retirement. Pasting his bread with marmalade, he looked at me pensively. ‘You know Lars, at breakfast my children said something that made me think.’ He took a bite, carefully considering how to continue. ‘Do you realize that it is actually strange that we devote our lives to looking at rodent molars?’

Of course, his children were right. If you aim to impress an attractive stranger at the bar about being a palaeontologist, you better start rambling about dinosaurs. ‘Leading specialist in the taxonomy of Miocene hedgehogs’ will not cut it. As a student, I even once vowed that I would never waste my time on something as obscure as mice teeth. But it only took a three-week lab to convince me that they are really cool, and I have been addicted ever since.

So what is so nice about the teeth of mice? There are a few things you need to know first. The molars of small mammals are very typical: you can identify the species by looking only at the teeth. They are very tough, and so they preserve well and in great numbers. And because teeth are used to eat (!), you immediately know something about their diet. In short, there is a lot of information in these tiny objects, which are usually just 1 mm long.

The fun starts at collecting. The public perception of palaeontological excavations is a bunch of people lying on the ground, carefully brushing sediment from a bone. It makes great television, but does not show the cramped knees, the sunburn, or the hungover student peering over your shoulder. Having endured all that, at the end of the day you are lucky if you have recovered one fossil.

We don’t use toothbrushes, at least not for excavating. The tools of the trade are a pick-axe, a shovel, and a stack of bags. The hard work lies in gathering clay from a fossiliferous layer, and putting it out to dry. After that, the sieving starts. You get to play with mud and water all day long. It takes you back to kindergarten, but this time you actually get paid to do it. And once everything is processed, you can end up with hundreds of fossils.

It is that sheer quantity that is the real trick. You don’t study a single fossil (I feel very sorry for palaeoanthropologists), but an entire fauna at once. If you have various fossiliferous levels in one hillside, you can see the morphological changes as individual lineages evolve, and clear changes in the composition of the fauna which reflect the changes in the environment. Flying squirrels disappear from the record as the forest gives way to plains; beavers appear when the climate turns moist. Each collection of small mammal molars gives another glimpse of the landscape in a time long gone. I am looking at rodent teeth, but I am studying a changing world.

Of course, it is always good to be reminded that the object of your studies is a little out of the ordinary — whether it is by your kids, the stranger at the bar, or even the manager who thinks that palaeontology is only about dinosaurs. But the story fossil mice have to tell is an intriguing tale. Apart from that, there is also the practical side to things. At least I’ll never strain myself lifting one of my fossils.

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Making predictive models

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