Scientists have discovered that the waters off New Zealand were once the home of a penguin so large it could look a full-grown human in the eye. The 60 million year old remains of the giant flightless bird were examined by a team led by Gerald Mayr at Senckenberg Research Institute and Natural History Museum in Frankfurt, who concludes that the species was one of the largest penguins ever found, standing 1.77 m (70 in) and weighing over 100 kg (220 lb).

If you pop down to Antarctica, you might come across a colony of the largest living penguins, the Emperor penguin (Aptenodytes forsteri), which stands 1.2 m (47 in) tall and weighs an average of 30 kg (66 lb). But in the distant past, penguins reached gigantic sizes – more than once.

The new giant is called Kumimanu biceae from the Maori words "Kumi," meaning monster, and "manu," meaning bird. The fossilized fragments of its skeleton were found in exposed strata in the Otago region on New Zealand's South Island and date back to the Late Paleocene, between 59 and 56 million years ago. This makes the penguin one of the oldest ever found and shows that gigantism appeared not long after penguins took to the sea and became flightless.

Though there was a larger species of penguin in Antarctica, it dates from later and only a few fragments of its skeleton have been found. Indeed, giant penguins have appeared a number of times in the younger epochs of the Eocene, which ended about 34 million years ago, and the Oligocene, which ended about 23 million years ago.

The humerus and a bone from the shoulder girdle (coracoid) Paleocene giant penguin, shown separated from the original bone cluster(Credit: Senckenberg)

According to Mayr, what is interesting is that Kumimanu and the other giant penguins aren't closely related, which indicates that gigantism evolved independently on more than one occasion.

So large why are modern penguins so small? The answer is probably to do with the rise of the marine mammals that could outcompete the giant birds.

"Giant penguins developed shortly after the mass extinction near the end of the Cretaceous, approx. 66 million years ago," says Mayr. "It is possible that the disappearance of large marine reptiles enabled the penguins to explore new ecological niches. However, with the subsequent appearance of other large marine predators such as seals and toothed whales, the penguins faced new competition and predation, which may have led to their extinction."

The research was published in Nature Communications.

Source: Senckenberg

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