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By Will Dunham
WASHINGTON, Nov 29 (Reuters) – A 4.5-meter-long prehistoric whale that sucked prey into its mouth represents a key missing piece regarding the evolution of today's huge filter-filtering whales, officials said Thursday. scientists.
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 "whale mother", a surprising intermediate stage of evolution between modern baleen whales and their toothed ancestors. Maiabalaena consumed fish and squid by sucking them in her mouth.
The evolutionary steps that have led to the modern giants of filtering baleen whales, such as the blue whale, the largest known or oldest animal on earth, have remained obscure. 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 Maiabalaena's position in the whales' family tree indicated that tooth loss had preceded the whalebone millions of years ago.
"This fossil demonstrates that the loss of teeth 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 Museum 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 before the innovation of filter feeding," 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 the muscles that depressed the tongue and contributed to sucking.
"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 at George Mason University, museum.
The research was published in the journal Current Biology. (Report of Will Dunham edited by Bill Berkrot)
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