skeleton

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.

Advertisements

A Treasure Trove of Moa in Whanganui

Last week the Moa Gallery opened at the Whanganui Regional Museum in Stage I of a visible-storage project that sees the entire moa bone collection out of boxes in the basement to where people can see it, both in display cases and on the internet. But why is the moa collection so important? Why put it all on display?

North Island giant moa (Dinornis novaezealandiae)

North Island giant moa (Dinornis novaezealandiae)

Whanganui has been known for its moa bones since the earliest days of European settlement. As far back as the 1850s Anglican missionary Richard Taylor collected enormous bones from old pa sites and sent them to the eminent zoologist Professor Richard Owen in England. Owen was the first scientist to recognise that these bones could only be from a giant flightless bird, and coined the name Dinornis for them; a “terrible bird” in the same way a dinosaur was a “terrible lizard”.

Moa bones are found throughout the country, and collecting them was a popular hobby from the 19th century onward, so most museums in New Zealand have a moa collection. You can find the bones in caves from birds that wandered in, or fell down sinkholes; in dunes, where the shifting sand covered and protected their skeletons; or in swamps, where moa were trapped and sank into the mire, accumulating in huge numbers over the centuries.

The 1937 excavation at Todd’s Hole

The 1937 excavation at Todd’s Hole

As more of the pool was extracted, excavation continued as walls were built to hold back the liquid mud

As more of the pool was extracted, excavation continued as walls were built to hold back the liquid mud

One such moa death trap was near Ūpokongaro, up the Makirikiri Valley, in a swampy pool named Todd’s Hole on the Todd Family Farm. Beneath a thin crust of soil was a funnel of liquid mud full of moa bones, plus a few more from farm stock that had wandered in more recently. At first the bones could be just yanked out with an iron claw, but when the vast size of the deposit became clear, representatives from the Museum, with a £1200 excavation budget, began a proper excavation. Over 1937 and 1938 a crane, bucket and sluice were built, hundreds of cubic yards of mud sorted through by hand and about 2,000 moa bones extracted, cleaned and sorted.

Back at the Museum, the Curator George Shepherd began assembling skeletons from the pile of bones, putting together 10 in all. In those days moa classification was not well understood and many species were thought to be represented in the find, some from just a single bone.

Today with the help of DNA we can put the bones from Makirikiri into just three species: Mantell’s moa, a small species found around forest edges and wetlands; the bush moa, another small slender species that lived in the forest and seems to have been the most common kind of moa in the area; and the North Island giant moa, with gigantic females 1.5 m at the shoulder and weighing perhaps 200 kg, with males only half that size.

Photo of the Makirikiri Moa skeletons in the new Museum wing 1968. They’ve since been reassembled into positions more like those of a living moa.

Photo of the Makirikiri Moa skeletons in the new Museum wing 1968. They’ve since been reassembled into positions more like those of a living moa.

The skeletons were put on display in the Museum and the rest of the bones put in storage until they were re-examined in the late 1980s by moa expert Trevor Worthy. He was the first to recognise that the moa collection from Whanganui was of international importance. Although other large moa deposits had been discovered, especially in the South Island, most of those bones had been sent around the world, traded, lost, or destroyed. The Whanganui collection is one of the most important in the world because it has stayed almost completely intact, which lets scientists study an entire community of moa trapped in the swamp over thousands of years: their age, growth rate, size and male/female ratio.

These bony rings support the trachea, or windpipe, of a moa and are sometimes found in a pile in the middle of a very well-preserved skeleton.

These bony rings support the trachea, or windpipe, of a moa and are sometimes found in a pile in the middle of a very well-preserved skeleton.

The moa species that ate leaves and twigs would also swallow small stones, known as gastroliths or gizzard stones, to help grind up their food, in the same way chickens swallow pebbles and grit. Sometimes one or two kilograms of smooth stones can be found in a pile in a sand dune long after the rest of the moa skeleton has crumbled away.

The moa species that ate leaves and twigs would also swallow small stones, known as gastroliths or gizzard stones, to help grind up their food. Sometimes one or two kilograms of smooth stones can be found.

The goal of the Museum is to make this collection accessible by putting it all on exhibition and also by photographing, registering, and 3D-scanning the bones so everyone in the world can see them, not just people able to visit Whanganui. The whole process will be happening in the gallery itself, where visitors can watch and ask questions. We’re hoping that our moa collection will put Whanganui on the map, not only for moa biologists but for anyone interested in these amazing giant extinct birds.

 

Dr Mike Dickison is the Curator of Natural History at the Whanganui Regional Museum.