Ancient history on the beach

030316PBmoa GOOD FIND: Dale Hudson with the piece of moa bone and a tibia tarsus of a similar size. PICTURE / PAUL BROOKS

When Jo Ockey found an odd-looking object on Castlecliff Beach and later discovered it was a piece of moa bone, it was only natural that it should eventually be donated to her husband's workplace, the Whanganui Regional Museum.
It was there that hubby, Dale Hudson, Exhibitions Officer, took Midweek to see the object in the office of Mike Dickison, Curator of Natural History.
"It was just kicking around the house," says Dale. "It was just like another rock that we found that was kind of interesting, just amongst a pile of other rocks."
Alongside a complete moa bone, it's easy to see where the "rock" fits into the skeleton of New Zealand's extinct bird, but also easy to see how it could be mistaken for an interesting rock.
Is it normal to find such things?
"It's unusual for New Zealand in world terms. There are very few ancient moa bone fossils found," says Mike, "but around Whanganui there's some sea-floor deposit that's washing out of a cliff somewhere, and several people have found them along the beach here. We've got a couple of others on display."
The bone has been fossilised into a form of dark rock, every cell being replaced by mineral, but the texture is still distinctively bone-like.
Mike says the action of wind, sand and tide would quickly erode the fossil away so it was a happy circumstance that Jo found it to add to the museum's collection.
"They're sometimes found stuffed full of shell and mudstone," says Mike.
The bone is a piece of the tibia tarsus of a giant moa, one of nine moa species of New Zealand, probably a smallish male, says Mike. A giant moa is about the size of a person.
"Jo thought it was an interesting stone with a hole in it. I thought it might have been petrified wood and the more I'd handle it I thought it looked organic," says Dale.
"At this time, a million years ago, there were no other land animals of that size; it's hollow, so it's a bird bone," says Mike, explaining how identification was made. "Dale's intuition was right."
Mike says he'd be happy if people brought in odd things found on the beach to be looked at by the museum's expert. "Sometimes a rock with a hole in it is just a rock with a hole in it ... but sometimes ... "
"They're amazing objects: so sculptural. I can see why people want to keep them. To think that was a living bird, walking around a million years ago. "We're very lucky here in Whanganui, so geologically rich, that this sort of thing is still coming out of the cliffs."
The bone is on display in a case.