Paleontologists Discover An Ancient Whale That Had Neither Teeth Nor Baleen

Posted: Dec 1 2018, 7:04am CST | by , Updated: Dec 1 2018, 7:28am CST, in Latest Science News


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Paleontologists Discover an Ancient Whale that had Neither Teeth Nor Baleen
Credit: Alex Boersma

The fossil reveals a surprising intermediary step between the baleen whales that live today and their toothed ancestors.

Blue whales, humpbacks and other groups of whales use hair-like plates in their mouths to filter prey from ocean water. This unusual structure allows these giant marine creatures to gulp down several tons of food each day, without having teeth. But so far, researchers have struggled to explain how and why whales evolved this type of feeding behavior.

Previous research suggests that ancient relative of our modern whales originally had teeth, which they apparently used to capture and consume large prey. Teeth were eventually replaced by baleen. It was also thought that baleen first emerged when whales still had teeth. But now Smithsonian scientists have discovered a surprising intermediate step in the evolution of innovative feeding strategy. New evidence based on careful analysis of a 33-million-year-old whale suggests that an ancient whale Maiabalaena nesbittae had neither teeth nor baleen.

"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 marine mammals. "Maiabalaena shows that the second phase of whale evolution is just as important for evolution over big scales. For the first time, we can now pin down the origin of filter-feeding, which is one of the major innovations in whale history."

Whales were the first mammals to evolve baleen. But unfortunately these delicate structures do not preserve well and are rarely found in the fossil record, leaving researchers without any direct evidence to understand its origin.

It is widely believed that toothed ancestors of baleen whales went through a stage of evolution in which they retained both teeth and baleen before completely losing their teeth and developing a filter-feeding system. To find out, researchers looked into the fossil of Maiabalaena which was found in the 1970s in Oregon and came from a period of massive geological change, during the early Oligocene period. But it was not until recently that researchers cleaned the fossil and then examined it with state-of-the-art CT scanning technology. They found that Maiabalaena lack teeth. Its upper jaw was also thin and narrow, making it an inadequate surface in which baleen can be established.

The ancient whale did not have the ability to chew or to filter feed, but it likely had strong cheeks and a retractable tongue. Those would have enabled it to suck water into its mouth, taking up prey like fish in the process. However, the system required a lot of energy and subsequently led to a major phase of whale evolution. The finding suggests whales lost their teeth and later independently developed baleen and filter feeding.

"A living baleen whale has a big, broad roof in its mouth, and it's also thickened to create attachment sites for the baleen,” said lead author Carlos Mauricio Peredo from National Museum of Natural History, "Maiabalaena does not. We can pretty conclusively tell you this fossil species didn't have teeth, and it is more likely than not that it didn't have baleen either."

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<a href="/latest_stories/all/all/47" rel="author">Hira Bashir</a>
The latest discoveries in science are the passion of Hira Bashir (). With years of experience, she is able to spot the most interesting new achievements of scientists around the world and cover them in easy to understand reporting.




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