Complete mitochondrial genome sequences of two extinct moas clarify ratiteevolution

The origin of the ratites, large flightless birds from the Southern Hemisph ere, along with their flighted sister taxa, the South American tinamous, is central to understanding the role of plate tectonics in the distributions of modern birds and mammals. Defining the dates of ratite divergences is al so critical for determining the age of modern avian orders(1-6). To resolve the ratite phylogeny and provide biogeographical data to examine these iss ues, we have here determined the first complete mitochondrial genome sequen ces of any extinct taxa-two New Zealand moa genera-along with a 1,000-base- pair sequence from an extinct Madagascan elephant-bird. For comparative dat a, we also generated 12 kilobases of contiguous sequence from the kiwi, cas sowary, emu and two tinamou genera. This large dataset allows statistically precise estimates of molecular divergence dates and these support a Late C retaceous vicariant speciation of ratite taxa, followed by the subsequent d ispersal of the kiwi to New Zealand. This first molecular view of the break -up of Gondwana provides a new temporal framework for speciation events wit hin other Gondwanan biota and can be used to evaluate competing biogeograph ical hypotheses.