New Fossils Reveals the Evolutionary History of the Sperm Whale

A new fossil is revealing a bit more about the family tree of the sperm whale, a species made famous by the novel, Moby Dick. Scientists have discovered a new species of an extinct pigmy sperm whale that clarifies key aspects of the evolution of sperm whales.

Sperm whales are known for their ability to dive to great depths and their acute sense of echolocation. Yet while other whales, dolphins and porpoises have a long fossil record, the smaller relatives of the well-known sperm whale have a poor record. This, in turn, has limited our understanding of the evolution of sperm whales.

Now, the new discovery may change things. The Panamanian fossil whales provides fresh evidence concerning the evolution of the sperm whale.

"The new discovery gives us a better understanding of the ancient distribution of these poorly known relatives of the sperm whale," said Jorge Velez-Juarbe, one of the researchers, in a news release. "Previously we knew of similarly-aged pigmy and dwarf whales from Baja California and Peru, but this new fossil fills in an important geographic gap in the group's ancient distribution."

The new whale species is called Nanokogia isthmia. It's known from the well-preserved skulls of two individuals. The fossils reveal that the evolution of sound emission and echolocation were far more complex than previously thought. At one time, the small sperm whales had a much larger spermaceti organ, which was downsized at least twice during the animals' evolutionary history. Currently, though, researchers aren't sure why this downsize occurred.

Whatever the case may be, these fossils do tell the researchers a bit more about the sperm whale and about its ancient ancestors.

The findings are published in the journal PLOS One.

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