Jacob Blokland, a graduate of the University of Canterbury, Christchurch, found evidence of the penguins, which have been given the name Kupoupou stilwelli, after examining fossils from the Chatham Islands which are in the southern Pacific near New Zealand's South Island.
At the time this penguin was around — between 62.5 million and 60 million years ago — there was no ice cap at the South Pole and the seas around New Zealand were tropical or sub-tropical.
Blokland said Kupoupou was much smaller than its human-sized relative, the so-called giant pengiun, Crossvallia waiparensis. "Kupoupou was comparatively small – no bigger than modern King Penguins which stand just under 1.1 metres tall," he said.
“This penguin is the first that has modern proportions both in terms of its size and in its hind limb and foot bones (the tarsometatarsus) or foot shape.”
An artist's impression of Kupoupou stilwelli. Supplied
Also working on the fossils were Professor Paul Scofield, senior curator of Natural History at the Canterbury Museum in Christchurch, and Associate Professor Catherine Reid, as well as Flinders palaeontologist Associate Professor Trevor Worthy.
“We think it’s likely that the ancestors of penguins diverged from the lineage leading to their closest living relatives — such as albatross and petrels — during the Late Cretaceous period, and then many different species sprang up after the dinosaurs were wiped out,” Professor Scofield said.
“It’s not impossible that penguins lost the ability to fly and gained the ability to swim after the extinction event of 66 million years ago, implying the birds underwent huge changes in a very short time. If we ever find a penguin fossil from the Cretaceous period, we’ll know for sure.”
The new species is based on the fossilised bones of five partial skeletons. Another two specimens showed a second larger penguin species was also present on the main Chatham Island but there was not enough material to formally name it.
All described skeletons were found between 2006 and 2011 by a group led by Monash University palaeontologist Jeffrey Stilwell, Dr Alan Tennyson from Te Papa Tongarewa the Museum of New Zealand and Professor Julia Clark from University of Texas at Austin were in the group and are also-coauthors of a paper published in the US journal Palaeontologica Electronica.
The species is named after Associate Professor Stilwell with all specimens now cared for by Te Papa.