Image caption The ancient penguins are shown in this artist's impression

A large extinct penguin has been reconstructed from fossil remains discovered in New Zealand.

Researchers used bones from two separate examples of the ancient birds, using the skeleton of a modern king penguin as a guide.

They show the 25 million-year-old Kairuku penguin was tall at 1.2m (4ft 2in), with an elongated beak and large flippers.

The team's work appears in the Journal of Vertebrate Paleontology.

The reconstruction shows that the Kairuku penguin was easily the largest of the five species that were common to New Zealand during the Oligocene time period.

The efforts were partly inspired by the bird's unusual body shape, which is different from any other known penguin, living or extinct.

"Kairuku was an elegant bird by penguin standards, with a slender body and long flippers, but short, thick legs and feet," said co-author Dr Dan Ksepka, from North Carolina State University, US.

"If we had done a reconstruction by extrapolating from the length of its flippers, it would have stood over 6ft tall. In reality, Kairuku was around 4ft 2in tall or so."

Twenty-five million years ago, New Zealand was an attractive location for penguins because it offered both food and safety.

Most of the present day country was underwater at that time, leaving isolated, rocky land masses that protected the penguins from potential predators and provided them with a plentiful food supply."

The name Kairuku comes from a Maori word that loosely translates to "diver who returns with food".

Bigger penguins have been discovered: at least two extinct species discovered in Peru stood about 5ft (1.5m) tall.