Let's Learn About Whale Evolution
So I just saw a post where someone overheard another person saying “didn’t whales evolve from wolves?” and I wanted to take a moment to discuss the way whales actually came to be. It’s a subject that I’ve always been really interested in, and it’s really crazy, so hopefully you enjoy hearing about it too.
Most people, at some point (hopefully early) in their lives, are told that whales are mammals, and have trouble processing that information. Much of whale anatomy doesn’t resemble what we think of as mammal anatomy at all. But yes, whales are mammals. They breathe through lungs, they give live birth, and they produce milk. Yum. Some whales, bottlenose dolphins for example, are hailed for their intelligence, to the point that they are given rights as “non-human persons” in some legalities. Modern day whales form the order Cetacea, and the two suborders Mysticeti (baleen whales) and Odontoceti (toothed whales.) The flukes, which make up the tail fin of the whale, is not the whale’s feet but actually a boneless tail modification. Whales retain vestigial hindlimbs from their days as quadrupedal animals. Below is an illustration of a typical Mysticetus skeleton.
Nothing on earth today resembles whales in any form except for other whales, so it may come as a shock to learn that the closest modern-day relative of whales is the hippopotamus. Whales are descendants of carnivorous quadrupedal terrestrial ungulates, which is to say, meat-eating four-legged land-dwelling hoofed mammals. The two terms that shouldn’t add up in there are “carnivorous ungulates.” Back in the day, the ancestors of things like goats and antelopes were top predators. I swear I’m not making this up. Look up “Andrewsarchus,” it’s hilarious and terrifying. Anyway, the first animal to really be classified as on the way to whalehood is Pakicetus. Take a look at him.
You can kind of see where they got the “evolved from wolves” idea here. This animal is the first known creature referred to as a whale on the fossil record. It was thought to be nearly entirely terrestrial, and is only known to be a whale because of its bone structure. Neat stuff.
Next, we’ve got Ambulocetus. The name literally means “walking whale.” Ambulocetus was much bigger and whalier, with a huge cone-shaped head and powerful swimming muscles. It’s thought to have swam by swishing its body up and down, like today’s whales, rather than side to side, like a fish or crocodile. It was probably an ambush predator, waiting in the shallows to lunge at thirsty prey, like modern crocodiles. Here’s a picture.
I don’t really like that depiction too much, so my recommendation is to watch the first episode of “Walking with Beasts,” there is some really great information about Ambulocetus there.
After Ambulocetus, we move on to the ocean-dwelling cetaceans, the Remingtonocetids. There’s really not too much to talk about here, they’re just more streamlined with an even bigger snout and a longer tail and smaller limbs. Here’s Kutchicetus.
That’s not too thrilling, pretty much looks like an shrew-otter hybrid, but hang in there because it’s about to get weird.
Protocetidae was a pretty mixed bag. On the one hand, we have Rhodocetus:
He pretty much looks like what we’re used to. Four feet, straight pointed tail. But then you’ve got Protocetus:
Now that’s more like what we’re used to today. As you can see, he’s got flukes, his hindlimbs are pretty small, and his nose is headed toward his forehead. Looks like he’s even got the beginnings of the dorsal fin seen in a lot of modern day dolphins. Moving right along.
Now we’ve got two different types to work with– Dorudontidae and Basilosauridae. Let’s start with Dorudon because he’s not as cool.
Pretty much what we have here is a dolphin with too many flippers and no melon (the melon is a whale-specific organ that allows modern day whales to use echolocation.) We’re now fully aquatic across the board. Next, we’ve got Basilosaurus. You can probably tell how cool he is just from his name.
These guys are enormous, long-bodied, horrifying sea monsters. Again, your homework is to watch Walking with Beasts, episode 2. There’s not much to tell at this point, we’re basically looking at whales, but that show has some good information and fantastic fight scenes. Definitely tune in.
From then on, it’s been pretty minor changes. Lose a limb here, grow a melon there, yadda yadda. It’s been a weird trip for whales, but they’re not the first to do this. Back before any of this happened, the reptiles took to the sea, and we saw animals like Mosasaurs and Ichthyosaurs. Even today, we have things like otters, seals, and manatees, which seem to all be in various degrees of evolution toward aquatic living. Evolution is a really, really fascinating thing, and it’s something I encourage you to spend time looking at on your own. Modern life has a great backstory.
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