Robert Boessenecker from the University of Otago's Department of Geology, New Zealand found that the fossil of the 4-5 metre long Herpetocetus, thought to be the last survivor of the primitive baleen whale family called cetotheres, may be as young as 700,000 years old.
Boessenecker said the previously youngest-known fossils of this whale were from the pre-Ice Age Pliocene epoch, approximately 3 million years ago, a time before many modern marine mammals appeared. Baleen whales of this type were most common much earlier, about 10-15 million years ago.
"Other baleen whales underwent extreme body size increases in response to the new environment, but this dwarf whale must have still had a niche to inhabit which has only recently disappeared," Boessenecker said in a statement.
The finding indicates that the emergence of the modern marine mammals during the Ice Age may have happened more gradually than currently thought, he said.