In honor of Daisy, we very slowly got this post about sloths together
EXTERIOR shot of Blizzard Watch Amalgamated
It’s a violently stormy night. Camera pans across the sheer basalt structure as a forked blast of lightning illuminates the many gargoyles and other fiendish art that decorates the foreboding and forbidding edifice. The camera finds a single, brightly lit window atop the massive black spire. As it passes through the window, we find ourselves in the BLIZZARD WATCH NEWSHUB, where massive but antiquated computers are fed punch cards and spit out reams of paper. Seated atop a massive throne that’s behind a sensible desk, Editorial Director LIZ HARPER chews on a carrot and pounds her fist on the desk.
HARPER: Bring me sloth facts! The readers are gaga for sloths, thanks to Daisy, and I mean to give them all the sloths they can handle. Sloth it up! I want cute sloth videos! Where did they come from? Where do they fit in the tree of life? Are they dating any celebrities? Sloth me!
None of that happened, of course. But we are going to talk about sloths, because Daisy is awesome and it’s a thinly veiled excuse for some paleontology and zoology talk which are things I dearly love.
A Mighty Mammal Dynasty
Who are the sloths? Well, they are Xenarthrans, related to Armadillos and Anteaters. They’re closely related to Anteaters, and both groups make up the Xenarthran order Pilosa. By themselves, the sloths consist of six species — four species in the genus Bradypus, the three toed sloths, and two species in the genus Choloepus, also known as the two-toed sloths.
Amazingly enough, despite the fact that all living sloths are suspensorial arboreal animals, meaning they spend close to their entire lives hanging from trees, Bradypus and Choloepus are not closely related. The three toed sloths are the only surviving members of the Megatheroidea, making them related to one branch of massive ground sloths like mighty Megatherium itself. Meanwhile, our two toed sloth friends are members of the Mylodontidae, a completely different radiation of sloths. This means that despite all of their similarities, the three toed and two toed sloths aren’t closely related, making their adoption of the exact same mode of life a case of convergent evolution.
While all living sloths spend the majority of their time hanging from tree branches, or from their mothers when they’re wee lil things, there was once a massive array of diverse sloths that included aquatic sloths Thalassocnus that lived off the coast of South America, the rock climbing Diablotherium and of course the various families of massive ground sloths, ranging in size from that of a small deer to rivaling elephants in the case of Megatherium and the Mylodontid Lestodon. Sloths have in their time filled almost every niche available in their various American habitats save that of a predator, due to their somewhat lower metabolisms letting them subsist on foodstuffs like avocados others might have found insufficient, as well as their ability to eke every last resource out of an environment.
Modern arboreal sloths aren’t anywhere near as massive as their extinct giant ground sloth relatives, but that may be what saved them during the Quarternery Extinction, some 12,000 years or so ago, when the majority of sloths died out. Was it due to human encroachment in the Americas? Well, that probably didn’t help, and it certainly played a role in the extinction of the Greater Antilles ground sloths some 5000 or so years ago, but we suspect that most of the ground sloths died out because of climate change — the sloths got massive to help them deal with the ice age conditions at the time, and were put under pressure as things warmed up, which was then made worse when humans showed up with spears and group hunting techniques the big, slow animals couldn’t counter. Unlike a Smilodon, a human didn’t to saunter up to a four ton animal with massive digging claws and let it take a swipe at him, he could just get together with some friends and throw spears at it from a distance until it was dead. But to be fair, we still don’t know for sure how much of an impact humans had on sloths.
Sloths today are mostly just cute
I know you didn’t click on this post looking for a bunch of facts about ancient sloths. You want cute sloth videos. And I’m happy to oblige you! Sloths have a slower metabolism than most mammals — a general trend among the Xenarthrans — but they can still move more quickly than you may expect. They are also cute as heck. Here’s David Attenborough talking about sloths, which is basically the perfect combination of narrator and subject matter. Just listening to David Attenborough class up a conversation of sloth pooping will make you smile if you still have your soul.
Sadly, sloths are getting hammered by human deforestation, leaving to many sloth orphans who need homes. Now, this leads to extremely cute but also extremely sad videos of baby sloths being rescued. Sloths can in fact bite and claw you, by the way, so don’t just go up to one and poke it or anything. Here’s a video of baby sloths being swaddled because I love you. Yes, every one of you. Sloths are just great.
So hopefully this will keep the nonexistent version of Liz I invented for the intro of this post happy. Let’s close it out with a video of sloths on the ground, because why not? I mean, most sloths tend to move so slowly that they actually get algae growing in their fur, so I don’t know what you were expecting, but they’re not exactly great at thrilling chase scenes.
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