STL Science Center

STL Science Center

25 April 2015

Compare Away

Kiwi, Ostrich, and Dinornis
As recently extinct animals, Moa skeletons are in fairly adequate supply. There are burial grounds where the Maori tossed Moa skeletons in different places around New Zealand. These burial grounds have allowed for preservation and in some cases some fossilization of the remains; fossils can also be found around the islands where Moas died prior to Maori colonization of the islands. This allows us to reconstruct the skeletons of many individuals. That then allows us to compare Moas to other birds, in this case, living ratites that are the sisters to the Dinornithes. The egg may or may not be an actual fossil (I have not found any authentic sources one way or the other in regard to this and hesitate to make any assumptions), but the comparison between the eggs of Moa and other large ratite eggs is somewhat startling. Overall we can see here that the skeletons of Ostrich and Moa are quite similar, but the sternum of the Moa is very weak and almost appears to lack substance altogether. Part of the reason for this is the reduced nature of the forelimb. The wings of Moa were actually completely absent from all species, making the pectoral girdle vestigial at best and completely useless to the bird in terms of function. Lacking wings and the musculature needed to power wings, the bones eventually became evolutionarily defunct. These were obviously reduced beyond the point of vestigial structures and the powerful sternum of was also reduced. Those familiar with Hesperornithiformes are familiar with the absent pectoral girdle architecture of those birds and may be able to draw parallels with Moas.

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