12/26/2023 0 Comments Whale teethIt is rarely found in the fossil record, leaving paleontologists without direct evidence of its past or origins. But frustratingly, baleen, whose chemical composition is more like that of hair or fingernails than bone, does not preserve well. Whales were the first mammals to evolve baleen, and no other mammal uses any anatomical structure even remotely similar to it to consume its prey. But as the oceans around them changed and animals evolved, entirely new feeding strategies arose, including baleen filter feeding, says National Museum of Natural History predoctoral fellow Carlos Mauricio Peredo, the lead author of the study who analyzed the Maiabalaena fossils. As time went on, many descendants of these early whales continued to chew their food, inheriting this trait from their predecessors. When whales first evolved, they used teeth to chew their food, just like their land-dwelling ancestors. For the first time, we can now pin down the origin of filter-feeding, which is one of the major innovations in whale history." " Maiabalaena shows that the second phase of whale evolution is just as important for evolution over big scales. "When we talk about whale evolution, textbooks tend to focus on the early stages, when whales went from land to sea," said National Museum of Natural History's curator of fossil marine mammals. Using new methods to analyze long-ago discovered fossils housed in the Smithsonian's national collection, the team, which includes scientists at George Mason University, Texas A&M University and the Burke Museum of Natural History and Culture in Seattle, have determined that this toothless, 15-foot whale likely had no baleen, showing a surprising intermediary step between the baleen whales that live today and their toothed ancestors. 29 issue of the journal Current Biology, scientists at the Smithsonian's National Museum of Natural History and colleagues describe for the first time Maiabalaena nesbittae, a whale that lived about 33 million years ago.
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