Scientists unearth whale fossils

Press, 24 August 1988, Page 34

Scientists unearth whale fossils

NZPA-Reuter Wellington New Zealand scientists have unearthed the graves of 30-million-year-old whale fossils which could shed light on the origins of the species and provide clues to climatic changes at the time. Geologists have dug up some 20 baleen whale skeletons near Waitaki Valley in the south of the South Island and estimate hundreds more may be there. Baleen whales are like minke which do not have teeth.

“The abundance of whales here at this time may reflect major geological changes in the southern hemisphere,” said Dr Ewan Fordyce, the geologist in charge of the project.

The fossils are claimed to be the oldest baleen skeletons found.

Dr Fordyce said older whale types have been found elsewhere but they are further back in whale ancestry and looked more like modern-day seals.

The fossils show baleen whales have changed little in the intervening period and this gives a clue to climatic changes.

Baleen whales are known to feed mostly in high latitude polar regions. The find indicates the climate in the area at the time was not as moderate as previously thought. Dr Fordyce said baleen whales now feed above latitude 60deg. while the Waitaki Valley is about 45deg. south.

“It tells us about the first appearance of highlatitude polar food resources. It is also telling us that maybe this was a time of major cooling or change of the world’s oceans,” he said.

Dr Fordyce said it was hard to be precise but the change in climate was up to sdeg. Celsius over a few million years. “That is a major change. If that happened today we would regard it as going into an ice age,” he said.

The find, at between 150 m. and 200 m above sea level, indicates New Zealand then bordered the Southern Ocean and the sea level was much higher. New Zealand was part

of the vast supercontinent known as Gondwana, an amalgam of what is now India, southern Africa, South America, Australia, New Zealand and Antarctica. "The fossil find certainly supports the theory of the break-up of Gondwana,” Dr Fordyce said. “It fits it all together rather nicely.” Until now, the climate of Antarctica was thought to have been rather moderate until 40 million years ago in spite of its polar position, Dr Fordyce said.

Before the break-up of Gondwana the moderate climate was probably caused both by the influence of continuous coastlines to the north with the more temperate land

masses of Australia and South America, and by the lack of a circum-polar ocean, Dr Fordyce said.

The climate deteriorated 30 million to 40 million years ago as Australia and South America drifted away to leave Antarctica thermally isolated from warmer latitudes by the Southern Ocean.

Changes occurred in 1 ocean temperatures as the polar continent cooled. This saw the evolution of the cold Antarctic current which now sweeps from west to east around the Southern Ocean.

“I suggest that the development of new oceanic and climatic patterns in the south probably triggered the evolution of baleen whales, character-

ised by their new filterfeeding strategy,” Dr Fordyce said, “The seas of New Zealand may have been vitally important in this evolution.” He said New Zealand offered great promise for new discoveries. His project was funded by the National Geographic Society.

“It is one of the last frontiers of natural history. There has been an enormous amount of work done in the northern hemisphere and a bit down in South America but New Zealand fossils have only just been touched,” he said. “Almost everything we find turns out to be something new, something unsuspected.”