Boning up on specialist matter

Boning up on specialist matter

Dr Eric Dorfman, director of the Whanganui Regional Museum, has a predilection for skeletons – and makes no bones about it. The museum is mausoleum, I mean home, to a remarkable number of bony structures, including a complete skeleton of a long extinct great auk. As well as a fascination for extinct species, among Eric’s many accomplishments was a time spent teaching zoology at the University of Sydney, so the anatomy of animals is of particular interest.

The object of this article is to make morphological comparisons between skeletons of different species, showing, mostly, the similarities.  We looked at the skeleton of a penguin, then that of a lizard, a lace monitor or goanna, seeing the bones of a ‘hand’ – similar components, scaled differently – in each and every bony framework, and not a lot different from a human hand. And look! A flamingo skeleton!

Using the skeletons of a hawk, the lizard, the flamingo and the penguin, as well as a large animal skull, probably from a cow, Eric made comparisons of particular bony parts. “What’s interesting about this is that it is a real lesson in evolution when you start looking at how these things are the same basic morphology [structure],” says Eric. “If you look at the hawk, as on most birds, the upper bill is thicker and bigger than the lower bill. But if you look at the flamingo, the reverse is true. It’s because to feed, they hold their heads upside down. They lower their head into the water and filter out brine shrimp.”

So how did that beak structure happen? “Undoubtedly the behaviour precedes the morphology,” says Eric, “in that over time the birds that had a subtle difference in their beaks had more offspring because they fed at a more efficient rate, they were healthier and they had more eggs survive.”

Interesting fact: the colour of the flamingo is determined by its diet. “The pink comes from sequestering the pigment from the shrimp in their feathers. If you stop feeding flamingos their native food they turn white or very light pink.” You are what you eat.

“The beak of the hawk is for tearing, the penguin bill is for grabbing … but they are modified from the exact same origin.”  We carefully arranged the skeletons of the hawk, lizard and penguin on a table, together with the cow skull – kind of a mini-representation of House of Bones, a museum exhibition currently showing.

“Aside from the fact it’ll be a lot of fun, the most exciting thing for me is to show a rich skeletal collection and, what I’m hoping people will get from the exhibition will be an intimate look at skeletal structure and what different bones are used for. I hope also for an understanding about the connection between different biological groups that are actually similar and closely related.”

The hawk and penguin are obviously closely related, Eric pointed out, but those similarities extend to other species. “If you compare the goanna to the hawk, the spine is extremely similar and so much more is the same. To me, evolution is obvious when you look at these things together.”

The good doctor’s knowledge of ancient species is encyclopaedic but the evolution of birds and lizards comprised much of Eric’s discussion as we looked at the skeletons. “If you were to investigate an emu you can see a little ‘thumb’ in its wing,” says Eric, “and this is one of things to remember – not everything has a purpose. One of the mistakes we make is to think that everything we see on an animal has to have meaning and we look for that meaning.”

He compared the skull of the goanna with that of the hawk and the similarities were unmistakable. Cover them with flesh and life and you would never know how much the same they are.

 

Original article appeared in the Wanganui Midweek in September 2013.  Reproduced with permission from the Publishers.

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