Acacia heterophylla 1.4 million years ago. "A. heterophylla" sequences nest within those of the more diverse "A. koa", making the latter species paraphyletic. Both species are descended from an ancestral species in Australia, presumably their sister species, "Acacia melanoxylon"; the means of dispersal to Hawaii and then to Réunion (the latter trip a distance of 18,000 km) is thought to have been seed-carrying by birds such as petrels (the seeds of these species are not adapted for prolonged immersion in seawater). Both species also have very similar ecological niches, which differ from that of "A. melanoxylon". Acacia heterophylla Acacia heterophylla, the highland
Primitive koa finch Primitive koa finch fossils have been found on Maui and Oahu. It is believed that it inhabited lowland dry forests and savannas, where dominant plant species included "ka palupalu o kanaloa" ("Kanaloa kahoolawensis"), "aalii" ("Dodonaea viscosa"), "loulu" ("Pritchardia" spp.), and "koaia" ("Acacia koaia"). Unlike other species of "Rhodacanthis", "koa" ("Acacia koa") was not present in significant numbers in its habitat. The primitive koa finch was a granivore, with a bill adapted to eat the hard seeds and pods of legumes, especially "ka palupalu o kanaloa" ("Kanaloa kahoolawensis") and "koaia" ("Acacia koaia"). It may have also taken caterpillars and "aalii" ("Dodonaea