A new genus of ancient baleen whale has been identified after being discovered in the South Island's Hakataramea Valley, giving scientists new information on the prehistoric ancestors of modern day whales.
Skull and bones from the Toipahautea waitaki whale, which was named after the district it was located in, are estimated to be around 27.5 million years old.
The fossil was actually recovered 30 years ago, however its analysis to identify and name the new whale has only recently been completed.
University of Otago's Professor Ewan Fordyce said the Toipahautea waitaki was much smaller than modern whales, measuring about five metres in length.
He said this is not uncommon for that time period.
"For the most part they (the whales) were small animals compared to modern species, for example the minke whale, which is commonly used as a modern standard, can reach about 10 metres in length," he said.
Professor Fordyce said many people think in the past there were giants, and today we don't have them, but this isn't the case.
"The question is what has allowed them to grow them so big and probably it is their ability to crop massive food resources out in the open ocean.
"Big whales or big animals of any of sort in the sea can swim further and dive deeper than their smaller relatives, so it seems there is some sort of ecological evolutionary explanation."
Professor Fordyce said New Zealand is the Rosetta Stone of ancient whale species. The inscribed basalt stone, held in the British Museum, is a key to deciphering ancient languages.
"When the whales were living, the environment was rich and there were diverse populations of the animals and they got buried in conditions which were quiet and subsequently the fossils haven't been buried too deeply, so they are well preserved," he said.
He said most of the fossilised whales and dolphins he collects end up being a new species.
"It's really an exciting thing and it suggests to us there is a huge diversity still sitting in the rocks, waiting to be discovered."