Scientists have been astonished to find a strange whale species now confined to our end of the planet once lived off the coast of Japan and Italy.

"This is like finding a fossil kangaroo in Scotland," said one of the new study's authors, Dr Erich Fitzgerald, a senior curator of vertebrate palaeontology at Australia's Museums Victoria.

"It is a totally unexpected discovery."

Considered one of the most mysterious living species of whale, the pygmy right whale is today only found in the Southern Ocean around New Zealand, southern Australia and South America.

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But fossils of pygmy right whales have just been identified in Okinawa and Sicily.

The unexpected discoveries have just been published in the scientific journal Current Biology by an international team of scientists, including first author and Otago University alumni Dr Cheng-Hsiu.

They reveal a significant chapter in the whale's evolutionary history took place in the Northern Hemisphere - and point to the potentially huge impact climate change could have on today's whales.

"These findings are the first to show that pygmy right whales - as endemic to southern waters as koalas are to Australia - had ancient relatives in the Northern Hemisphere," Fitzgerald explained.

"They provide new insights into how climate change has profoundly impacted the distribution of whales throughout the Earth's oceans over millennia, and also point to how living species may be impacted by climate change, now with an added human dimension, in the future."

The pygmy right whale is the most bizarre living whale species - it is the smallest, it has strange overlapping ribs not seen in other marine mammals, and virtually nothing is known about its biology and behaviour.

An artist's illustration of the pygmy right whale. Photo / Carl Buell
An artist's illustration of the pygmy right whale. Photo / Carl Buell

What scientists know about its evolution has been garnered from a handful of just three fossils, which are between three and eight million years older than those just uncovered.

The Japanese fossil, consisting of part of a skull, is between 500,000 and 1 million years old, and the Italian fossil, an ear bone, is between 1.7 and 1.9 million years old.

The anatomy of these fossils was so similar to bones of the living pygmy right whale it suggested they could be the same species.

The new findings suggested that global cooling during the Pleistocene era, when vast polar ice sheets spread in both hemispheres, forced pygmy right whales north and eventually helped them to spread across the equator.

Then, as the glaciers naturally receded over millennia, the habitat of pygmy right whales once again shifted south, to where they live today.

Dr Felix Marx and Dr Erich Fitzgerald with pgymy right whale specimen from Museums Victoria's collection Photo / Museums Victoria
Dr Felix Marx and Dr Erich Fitzgerald with pgymy right whale specimen from Museums Victoria's collection Photo / Museums Victoria

Warming of the climate made the equator increasingly difficult to cross, so remaining pygmy right whales in the Northern Hemisphere eventually became extinct.

This pointed to the potential huge impact of ongoing climate change on today's whales, said co-author Dr Felix Marx, a research associate at Museums Victoria and Monash University.

"The natural changes to the Earth's climate now have an added human element, that may drive a reorganisation of the current dispersal of whales and marine mammals.

"For example, a warmer world may see the pygmy right whales driven further south towards the pole."

The finding also raised the possibility of fossils of other marine fauna, such as southern walruses and northern penguins, being found in the Northern Hemisphere.

However, at the moment the true extent of such occurrences was obscured by the globally poor Pleistocene fossil record.

Fitzgerald said the unexpected finding had created even more curiosity into the story of the pygmy right whale.

"These fossil finds out of left-field may be just the first step towards uncovering a much more expansive and complex evolutionary history for the pygmy right whale."