Were Malagasy Uncarina fruits dispersed by the extinct elephant bird?

Abstract

We hypothesise that the spiny fruits of the endemic Madagascar
genus Uncarina (Pedaliaceae) are trample burrs that evolved to be
dispersed on the feet of the extinct elephant bird (Aepyornis). Our
evidence is: i) the morphology of the fruit with its large grapple
hooks is more likely to attach to a foot than to adhere to fur and
ii) the presentation of mature fruits on the ground rather than in the
canopy. These differences to adhesive burrs make lemurs unlikely
dispersers. We argue, given the absence of other large terrestrial
mammals in Madagascar, that the most likely dispersers of
Uncarina fruits were the extinct large birds. If correct, our hypothesis
has implications for conservation of Uncarina, the biogeography
of the elephant birds and dispersal biology. For
example, we predict that the demography of Uncarina will be
skewed towards adult plants, and that the dispersal mutualism
could possibly be rescued by domestic animals.