Korora oliveri, a tiny mystery
Korora is the name for the living Little Blue Penguin in Maori. It is also the genus name of one of the smallest fossil penguins, chosen to indicate the animal’s small stature.
Korora oliveri is not the smallest fossil penguin ever discovered – that honor belongs to Ereticus tonnii. In fact, Korora oliveri would probably have stood about as tall as your average aquarium Humboldt penguin, although this estimate is not very exact because this species is only known from a single bone. Korora is remarkable because the fossil record of penguins is dominated by larger taxa. The vast majority of fossil penguins were at least as big as the King Penguin. Very few small species are known until we reach the more recent geological epochs.
Korora lived in New Zealand during the late Oligocene, about 25 million years ago. It swam alongside giants – most of the other penguins known from this area and time are huge, towering creatures including some of the largest that ever lived. It seems like smaller penguins were very rare in the area – as more and more large penguin fossils have been harvested from the relevant rocks they overwhelmingly belong to large species. This suggests that penguins focused on a different niche in the Oligocene. Most species probably were eating larger fish and sitting higher up the food chain, playing a role more like that of seals than modern penguins.
Korora remains a puzzle for penguin paleontologists. With only a single specimen, it is very difficult to figure out where this species belongs in the penguin evolutionary tree. If it turns out to be closely related to its larger contemporaries, then it would provide evidence for dwarfing in an ancient penguin lineage – perhaps downsizing from its ancestors in order to exploit smaller prey. If, on the other hand, Korora is more closely related to living penguins than these large taxa, it may be the herald of the modern penguin radiation – smaller, avoiding direct competition with marine mammals, perhaps more specialized for catching krill than fish. Trying to determine which of these hypotheses is correct is futile at the moment – we need more fossils to even start understanding what this penguin ate or how modern its skeleton was. This is why paleontology is such an exciting science. Some questions can be answered by more work, others only by new discoveries. Korora awaits the latter.