An ancient whale without teeth was the precursor of the modern giants of cetaceans

WASHINGTON (Reuters) – A pre-historic 4.5-meter-long whale that sucked prey into its mouth represents a key missing piece about the evolution of today's huge filtering whales, scientists said Thursday.

The researchers described Oregon's discovered fossils of a whale called Maiabalaena nesbittae, which lived 33 million years ago and possessed neither teeth nor baleen, material used by modern filtering whales to extract large quantities of prey from the water.

They called Maiabalaena, which means "mother whale", a surprising intermediate stage of evolution between modern baleen whales and their toothed ancestors. Maiabalaena was eating fish and squid by sucking them in her mouth.

The evolutionary stages that led to modern filter giants such as the blue whale, the largest known or oldest animal on Earth, were still unclear. Baleen is a flexible material made of keratin, the same material that is found in hair and nails.

One of the main hypotheses was that, at the beginning of the evolution of baleen whales, they possessed both teeth and baleen before becoming toothless. The researchers said that Maiabalaena's position in the whale's family tree indicates that tooth loss preceded baleen whales by millions of years.

"This fossil demonstrates that the tooth loss and the origin of the baleen are distinct evolutionary changes and that the two changes do not overlap," said Nick Pyenson, curator of Fossil Marine Mammals at the National Gallery of Canada. natural history of the Smithsonian Institution, and author of the book "Espionage des wales"

"Maiabalaena suggests that the major evolutionary changes in the way whales feed, such as the loss of chewing, must have occurred prior to filter feeding innovation," added Pyenson.

Whales are marine mammals. The first whales emerged from land ancestors looking like wolves about 50 million years ago. All the first whales had teeth.

The earliest direct fossil evidence of baleen dates from 11 million years ago, but scientists suspect that the first whales with baleen appeared about 23 million years ago.

Fossils found near the Pacific coast in Lincoln County, Oregon, showed that Maiabalaena had well-developed bones in the throat, which served as attachment points for muscles that depressed the tongue and produced aspiration.

"Feeding by suction may seem strange to an ancestor of blue whales today, but it is actually a very common mode for live tooth whales. such as sperm whales and many species of dolphins, "said Carlos Mauricio Peredo, paleobiologist from George Mason University, museum.

The research was published in the journal Current Biology.