Prehistoric Toothless Whale Among Oldest of Its Kind

A fossil found in South Canterbury is now one of the earliest members of the filter-feeding family of behemoths known as baleen whales. Modern baleen whales include many of the world’s largest cetaceans, such as blue, fin, humpback, right, bowhead, and minke whales. National Geographic reports.

The new species has been named Toipahautea waitaki, which roughly translates from Māori as “baleen origin whale of the Waitaki region.” It dates back 27.5 million years, say the authors of a study describing it in the journal Royal Society Open Science. At this time in the mid-Oligocene epoch, the region was an island archipelago lapped by the shallow waters of highly productive seas.

The very ancient ancestors of modern whales and dolphins, or cetaceans, were land-living carnivores that entered the seas around 50 million years ago, slowly losing their legs through evolution and adapting to an ocean-going way of life.

The first whales were all toothed, like modern sperm whales, says study author Ewan Fordyce at the University of Otago. But some later lost their teeth, developing plates of bristle-like baleen in their mouths that’s used to filter small prey such as krill from the water.

Until recently, scientists have known very little about precisely when the first baleen whales evolved. The oldest known relative of baleen whales is the 36-million-year-old Mystacodon selenensis, which was discovered in Peru and described in 2017 – but that species still had teeth. By contrast, Toipahautea had a long, toothless jaw and is thought to have fed using plates of baleen.

“As sure as the sun rises in the east, we are going to find older baleen whale specimens,” Fordyce says. “But right now, it anchors the modern baleen whale lineage to at least 27.5 million years.”

The fossil of Toipahautea was found in January 1988 in the Hakataramea Valley in South Canterbury, but was only analysed in detail recently.

At 5.8m in length, or about half the size of a modern minke whale, Toipahautea was much smaller than most baleen whales today. “People look at the fossil record and think the early history of many animals is filled with giants, but not for whales. It’s only in recent geological times that whales have achieved really large sizes,” Fordyce says.

Original article by John Pickrell, National Geographic, April 19, 2018.

Photo by R Ewan Fordyce.