Once upon a time, all whales had teeth. But scientists have long been confused about how we got from there to the several baleen whales we have today.
Fortunately, a forgotten whale skull just cracked the case.
According to Nature, the 33 million-year-old skull was found in Oregon in the '70s and had been in the Smithsonian National Museum of Natural History collection — but no one had looked at it closely enough.
Once researchers did, they realized it unlocked a huge chunk of whale evolution.
Science magazine reported that scientists previously had theories about how whales transitioned from teeth to baleen. One hypothesis was that they once had both teeth and baleen at the same time. Another theory suggested that whales slowly started to use the cracks between their teeth as an early form of baleen to filter food.
The skull now suggests something completely different.
According to Science, the skull didn't have the jaw structure to support either teeth or baleen. This indicates there was a period of time before whales developed baleen when they were figuring out toothless ways to eat.
Science reported that the researchers believe their whale skull shape supports the idea of suction feeding.
You know, like modern-day whale sharks use.
Phys.org reported that another whale skull studied in 2016 and nicknamed Alfred, does have teeth, but it also has a suction-feeding setup.
Grooves between its teeth indicate that the animal wasn't using them to chew, but rather as an early form of baleen.
Water and food and other particles were then rushing between the teeth with each suction and wearing them down.
Over time these whales likely lost their teeth all together as suction feeding became the new norm. Phys reported that the likely next step in evolution came to solve a problem: What to do with all the water these suction feeders were breathing in.
Whale sharks use their gills to dispose of excess water, according to Azula.
But filter-feeding whales needed to develop baleen in order to strain water back out without losing their meals.
It's interesting to see how these whale skulls help scientists track the evolutionary points for these marine mammals. And Newsweek reported that the research doesn't only help us look back.
Filling in the gaps to determine how quickly whales evolved in different ways could indicate how responsive they'll be to continued (man-made) changes to their environment. Can they evolve fast enough to keep up?