Tuesday, 6 September 2016

I've Gone Full Mammal

Can you be half a mammal?

Last month I attended SVPCA, The Symposium for Vertebrate Palaeontology and Comparative Anatomy. One of the most important reasons for attending conferences is the chance to chat with colleagues, network and share ideas. This year I was also presenting a talk on the tritylodontid, Stereognathus. For those unfamiliar with these little critters, they are small mammal-like creatures that appeared in the late Triassic, successfully ground their way through the vegetation of the Jurassic and Early Cretaceous, then disappeared from the fossil record.

Mark Witton's gorgeous reconstruction of Stereognathus ooliticus. You can buy a print here.
 
I say mammal-like creatures, but recently I've been chewing over the term "mammal-like".

Scientists chose a point at which an animal has enough features to be called a “real” mammal, but these are just the labels of humans, designed to give order to a chaotic natural world. Such labels allow us to talk about things with one another, but they also have limitations and repercussions for how we think about the natural world.

Our viewpoint as natural scientists is to look backwards and see the history of life as an accumulation of traits that “lead” to the groups we know today. But this is back to front: evolution is not moving towards an end-point, if anything, it’s blindly striding away from a starting point. The path it treads could lead anywhere, as each turn is taken randomly and preserved based on usefulness - with a good measure of serendipity.

So, rather than mammal-like, should we say cynodont-unlike? Well obviously not, that would be silly and hopelessly confusing.  But it does pose an interesting question about where the mammal "begins"? There are anatomical definitions - jaw joints, skull bones, dental characters - and undoubtedly if we could get hold of some ancient DNA there'd be genetic definitions too. However, despite learning the scientific, anatomical definitions, I like to remember that there really is no such thing as half-a-mammal, just like there are no living fossils.

Terminology is important. It drives us nuts, but we need to keep re-examining the words we use to describe things to keep them accurate and avoid any bias, whether it be temporal, cultural or moral.