Research links whales

University of Otago research that shows a northern hemisphere dwarf whale escaped extinction longer than previously thought also supports a theory that a still-surviving southern pygmy whale belongs to the same family.

That is the view of Otago geology department PhD student Robert Boessenecker, whose latest research focused on a whale fossil found in Northern California.

This fossil is of the 4m-5m long Herpetocetus, previously thought to be the last survivor of the primitive baleen whale family called cetotheres.

Latest research suggests the fossil may be as young as 700,000 years old, indicating the northern hemisphere dwarf baleen whale escaped extinction far longer than previously thought.

Mr Boessenecker (27), a US citizen, was ''delighted'' the paper had just been published in the international science journal Naturwissenschaften (The Science of Nature).

He had completed most of the first draft of his article on his laptop during a 12-hour flight from New Zealand to California late last year.

The previously youngest-known fossils of this whale were from the pre-Ice Age Pliocene epoch; about 3 million years ago - a time before many modern marine mammals appeared. It was ''very surprising'' that this whale had ''survived the great climatic and ecological upheavals of the Ice Age and almost into the modern era'', he said.

Other baleen whales had undergone ''extreme body size increases'' in response to the new environment.

The discovery also lent indirect support to a hypothesis about the modern pygmy right whale (Caperea marginata) recently published by Mr Boessenecker's Otago departmental colleagues Prof Ewan Fordyce and Felix Marx. Prof Fordyce and Mr Marx suggested this enigmatic Southern Ocean whale was not a true right whale but a member of the cetothere family and one of the closest relatives of Herpetocetus.

''Herpetocetus can be viewed as a northern hemisphere equivalent of the pygmy right whale: both are small-bodied with peculiar anatomy, possibly closely related,'' Mr Boessenecker said.

Herpectocetus and the southern pygmy right whale had apparently been ''the last two surviving members'' of the cetothere group.

And the northern hemisphere discovery made the southern whale theory ''much more plausible'', he said in an interview.

Baleen whales lack teeth and instead use baleen, a fibrous structure, to strain small prey such as krill and fish from seawater.

- john.gibb@odt.co.nz