New Sperm Whale Species Identified from Fossils in Eastern Japan

Maebashi, Gunma Pref., Oct. 19 (Jiji Press)--Fossils unearthed in Gunma Prefecture, eastern Japan, dating back about 15.5 million years, have been identified as a new species of sperm whale, offering clues to the evolution of the deep-diving marine mammals.

The species, named Miophyseter gunmaensis, combines traits of ancient and modern sperm whales. It is the third new sperm whale species identified from fossils in Japan, following discoveries in Nagano and Aichi prefectures in central Japan.

The fossils will be on display at the Gunma Museum of Natural History in Tomioka through Dec. 13.

Representing three individuals, they were discovered by local fossil enthusiasts between 1994 and 2011 along tributaries of the Tone River that flow through Tomioka and Annaka, both in Gunma. One specimen includes nearly a complete skeleton and is believed to be that of a calf measuring 3 to 4 meters long.

Modern sperm whales dive into the deep sea and suck in their prey, while their ancestors hunted in shallower waters and bit their targets, according to Toshiyuki Kimura, a curator at the museum.

[Copyright The Jiji Press, Ltd.]