[ad_1]
A 4.5-meter-long (15-foot-long) prehistoric toothless whale that has sucked prey into its mouth is a critical missing piece in the evolution of today's huge filtering whales, scientists said on 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.
Maiabalaena suggests that the main evolutionary changes in the diet of baleen whales, such as chewing loss, must have occurred before the filter feeding innovation.
Nick Pyenson, Smithsonian Institution
Maiabalaena suggests that the main evolutionary changes in the diet of baleen whales, such as chewing loss, must have occurred before the filter feeding innovation.
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. Researchers reported that Maiabalaena's position in the whale's family tree indicated that tooth loss had preceded baleen whales by several million years.
"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 Spy on whales.
"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 oldest fossils on Earth? No, they're probably just rocks
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.
[ad_2]
Source link
