In 2019, scientists determined that a kind of giant penguin, up to 1,6 meters tall, inhabited New Zealand in the Paleocene period, between 66 and 56 million years ago. Now, new discoveries point out that the southern hemisphere was not the only habitat of the “pinguinzilla”: a very similar, and even larger, bird also lived in the northern hemisphere.

A new study based on fossils found in USA e Japan point to the presence of animals of the plotopterid family in the region. These birds appeared between 37 and 34 million years ago and inhabited our planet for 10 million years. They were incredibly similar to penguins, but they weren't penguins.

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“These birds evolved in different hemispheres, separated by millions of years, but at a distance you would have difficulty separating them,” says Paul Scofield, curator zoologist at the Canterbury Museum, in New Zealand, and one of the study's authors.

“Plotopterids looked like penguins, swam like penguins, probably ate like penguins, but they weren't penguins,” he says.

Among the anatomical similarities are the long beak, with an elongated nostril, and similar bones in the shoulders, chest and wings. However, these animals could be even bigger than the New Zealand penguin, with some species reaching two meters in height.

Despite having feet with fins, like penguins, evidence suggests that plotopterids used their wings to propel themselves underwater, something that is unusual in today's water birds.

“We believe that both penguins and plotopterids had flying ancestors, who dived into the water to find food. Over time, these ancestors became better at swimming than flying, ”says another study author, ornithologist Gerald Mayr of the Senckenberg Research Institute and Museum of Natural History in Frankfurt, Germany,

The similarities between the two groups are a good example of "convergent evolution", when different species evolve similar characteristics in response to similar environments or lifestyles. Examples are the European red fox, a canid (relative of dogs and wolves), and the extinct Tasmanian wolf, a marsupial (relative of kangaroos).

Further studies are needed to understand why plotopterids became extinct, while penguins remain among us.

Source: Science Alert