The upland moa left behind fossil poo for researchers to study. Credit: George Edward Lodge via Wikimedia Commons.
The biggest birds today are the ostrich and Australia’s emu. Ostriches can be 2.7m tall and weigh 140kg! In the past, some birds were even bigger. Some of them, called moa, lived in New Zealand. One species of moa could grow to more than 3m tall and weigh a whopping 250kg! Moa went extinct about 600 years ago, soon after humans first made it to New Zealand.
Now scientists are trying to work out how the disappearance of moa might have affected other animals, plants and fungi in New Zealand. This study of ancient interactions between species is called palaeoecology.
You might be surprised by how they do it. The scientists studying the moa weren’t looking at fossil bones. They study fossilised poo, called coprolites. One of the coprolites was from a moa which lived 8,000 years ago. Another was just 600–700 years old.
A moa coprolite (fossil poo). Credit: Janet Wilmshurst.
The brightly-coloured, berry-like fungus, Gallacea scleroderma. Credit: Noah Siegel, Arthur’s Pass.
The fossil poo is recent enough that it still has some DNA in it. That includes DNA from the moa as well as the things it ate. When they looked at the DNA in the coprolites, the scientists found that the moa were eating a fungus. Mushrooms are a type of fungus, but the ones the moa ate are very different.
The fungus these moa ate is bright pink or purple. The scientists think this fungus evolved its bright colour to be more appealing to the moa because birds have good vision, but not such a good sense of smell. The fungus wants to be eaten by the moa, because that’s the only way it can spread and grow more fungus. “So it looks like there’s been some kind of mimicry,” says the lead researcher, Alexander Boast. “Effectively, these fungi look like berries on the forest floor which is remarkable.”
It also turns out that this species of fungus is very important for the growth of New Zealand’s forest trees. Now that the moa are extinct, the fungus may find it harder to spread. That could hurt the growth of New Zealand’s forests.
“Of course, it’s very cool to look at a past ecosystem, but we’re trying to understand just how complex ecosystems were in the past, and what kind of long-term legacy impacts of extinction might be,” says Alexander.
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