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Fossils show 'strange' marine mammals lived in pre-Ice Age Pacific

Fossils show 'strange' marine mammals lived in pre-Ice Age Pacific
A speculative life rendering of the fossil whale Balaenoptera bertae unearthed in the San Francisco Bay Area. Credit: Robert Boessenecker

OTAGO, New Zealand, Feb. 5 (UPI) -- The pre-Ice Age North Pacific included odd species of marine mammals like dwarf whales, double-tusked walruses and porpoises with underbites, a scientist says.

Doctoral student Robert Boessenecker of New Zealand's University of Otago said he identified 21 ancient marine mammals from fossil bones and teeth found in exposed rock layers in the San Francisco Bay area.

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"The mix of marine mammals I ended up uncovering was almost completely different to that found in the North Pacific today, and to anywhere else at that time," he said.

Among his finds, which were fossilized 5 million to 2.5 million years ago, is a new species of fossil whale, dubbed Balaenoptera bertae, a close relative of modern-day minke, fin and blue whales.

It would have been approximately 15 to 20 feet in length, slightly smaller than modern minke whales, Boessenecker said.

The strange marine mammals existed up until as recently as 1 or 2 million years ago, he said, likely maintained by warm equatorial waters and barriers to migration by other marine mammals posed by the newly formed Isthmus of Panama, and the still-closed Bering Strait.

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"Once the Bering Strait opened and the equatorial Pacific cooled during the Ice Age, modernized marine mammals were able to migrate from other ocean basins into the North Pacific, leading to the mix we see today," he said.

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