A Mummified Moa Helps Paleontologists Reconstruct Feeding Behavior

Shaena Montanari ,

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I write about paleontology, dinosaurs, and comparative biology.

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Let’s say you had a mummy of a giant extinct bird—what would you do with it? Marie Attard and co-authors had a brilliant idea. They stuck it in an MRI scanner to get a detailed look at its jaw muscles and reconstruct the way it ate, even though moas have been extinct for 550 years. This research appears this week in Proceedings of the Royal Society B.

Moas are extinct birds that are members of a group called ratites, which also includes living ostriches and emus. Moas were very large, up to 12 feet tall and more than 500 lbs, and lived exclusively in New Zealand. When they were living on the island, moas were one of the few terrestrial browsing animals shaping the composition of plants on the island, and in turn, the entire ecosystem. Their abrupt extinction is important to consider when studying the paleoecological landscape of New Zealand.
There are 9 species of moa, all extinct, and all with differently shaped skulls. Attard and colleagues used 3D modeling to perform virtual simulations of moa feeding. Usually in fossils this is done by modeling with muscles from living, closely related species, but in this study they were able to use the muscles of a moa mummy.

The original illustration of the mummy moa by Peter Trusler (1985) overlaid with the musculature of the skull (Credit: Marie Attard)

The story of the naturally mummified Megalapteryx didinus used in this study is a relatively mysterious one. The specimen is in the collection of the Museum of New Zealand Te Papa Tongarewa and was originally obtained by an individual in 1863 and later sold to the museum in 1943, its original collection spot never truly known. Half of it was rehydrated and dissected so its internal anatomy could be described, although an MRI is able to reveal much more useful data for 3D biomechanics reconstruction.
The 3D models were used to test technical performance during biting—essentially seeing the most likely feeding motions when taking into account the strength and musculature of the skull. They tested a variety of head motions, like lateral shaking and pullback. They found the extinct moas fed quite differently from living ratite birds. Also, Attard describes the different species of moa examined possessed a variety of dissimilar feeding habits: “Moa species living in the same geographical area may have been able to reduce competition for food resources by utilizing different feeding strategies to acquire food.”

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A Haasts eagle attacking a moa. (Image credit: John Megahan, PLOS Biology CC BY 2.5)

It appears their skulls were differently adapted to certain motions, like clipping vegetation with their beaks and yanking off leaves by depressing their heads. “It is likely that the coastal moa played an important ecological role in dispersing plant seeds by incorporating seed-bearing fruit in their diet. On the other extreme, the sharp edged bill of the little bush moa appears well suited to eating more tough, fibrous material,” Attard explained.  This new research indicates that the moa played a unique role in its ecosystem and their wide variety of feeding behaviors may indicate why multiple different species of moa were able to coexist in New Zealand hundreds of years ago before their extinction.

Shaena Montanari is a paleontologist at the University of Edinburgh. Follow her on Twitter at @DrShaena for the latest natural history and fossil news.