Giant Sloths Were Hairy

[carliro]

https://ichthyoconodon.wordpress.com/2025/01/18/giant-sloths-were-hairy/

[Faelrin]

Link to the article itself (not paywalled):

https://link.springer.com/article/10.1007/s10914-024-09743-2

Some interesting points raised. I'm not for or against either interpretation for the largest ones. What do you folks think of this?

[Crackington]

Interesting article-toys and models have generally shown them as big hairy beasts, so if the research is correct, they were right.

Must confess I hadn't realised there was an alternative thesis of them being hairless due to their large size and therefore ability to retain body heat, like elephants. Sounds feasible too.

Does anyone know of a Megatherium model with this less hairy approach? Would be intersting to see it.

[stargatedalek]

Isn't there literally preserved skin and fur from one? And also cave art of giant ground sloths showing they had fur?

The "3 ton rule" has always came across as deeply ridiculous to me so finding out one of the prim examples used to support it was just, wrong, would not surprise me in the least. Especially since I thought it had already happened...

[dinofelid]

The blog post links to Mark Witton's painting of a hairless Megatherium but doesn't link to his actual blog post, which is here--I don't actually read Witton as making any strong claim that Megatherium was hairless, just that it was likely not as "shaggy" (a word he uses a bunch of times) as often depicted, with hairlessness at least being plausible given the studies by Fariña that he cites (I also think the blog post is not representing his position fairly when it says that Witton 'argued dinosaurs above a ton were most likely featherless', his argument was more about it being at least plausible they could have been featherless, and the likelihood that if they did have feathers/dinofuzz, it would be a relatively short layer rather than something like long layer in many Deinocheirus depictions which he describes as a 'walking haystack').

If the new study's finding of Megatherium needing 3 cm fur in its climate is more accurate than the earlier Fariña studies he cites, that would rule out hairlessness but I dunno if Witton would consider this in the "shaggy" range (3 cm is certainly a lot shorter than something like Woolly Mammoth hair which grew up to 70 cm according to this article). The study also estimates Mylodon had a longer covering of 5 cm fur, which seems somewhat longer than what's suggested by the estimate Witton cites ('thermal neutrality at -4°C without fur, and -28°C once a 4 cm thick hairy covering was applied'), but Witton does note of Mylodon that "Unlike Megatherium, it would have routinely experienced sub-freezing temperatures and probably needed extra insulation to survive harsh winters". Witton also notes the tentative nature of the estimates from Fariña that he cites, saying "There's more work to do with Fariña's sloth calculations (both his 2002 and 2013 contributions to this topic are short and don't play with as many variables as I'd like) but these results are certainly thought-provoking as goes our considerations of the life appearance of sloths, and perhaps other giant extinct animals too."

[HD-man]

C @carliro Going forward, I recommend just linking to the paper itself like @Faelrin did. In this case, Carlos Miguel Albuquerque/Gwawinapterus/Ichthyoconodon/Johnfaa is an infamously bad source of info for reasons myself & others have discussed here ( https://dinotoyblog.com/forum/index.php?topic=4742.0 ) & elsewhere:

-See "Bad": https://www.deviantart.com/jd-man/journal/SD-Good-semi-good-and-bad-dino-sources-1-351589315

-See "Bad": https://www.deviantart.com/jd-man/journal/SD-Good-Semi-good-and-Bad-Dino-Sources-4-800236863

@stargatedalek "Isn't there literally preserved skin and fur from one?" Sorry to be the "actually" guy, but "contrary to popular belief, we do not have any skin preserved from megasloths: all the skin specimens we have stem from smaller ground sloth species" ( https://markwitton-com.blogspot.com/2019/10/megafuzz-under-microscope-how-credible.html ).

D @dinofelid "The blog post links to Mark Witton's painting of a hairless Megatherium but doesn't link to his actual blog post[...]the blog post is not representing his position fairly" Not surprising, given the above-mentioned discussions.

[dinofelid]

D @dinofelid "The blog post links to Mark Witton's painting of a hairless Megatherium but doesn't link to his actual blog post[...]the blog post is not representing his position fairly" Not surprising, given the above-mentioned discussions.

Thanks, I hadn't known about that blogger.

@stargatedalek "Isn't there literally preserved skin and fur from one?" Sorry to be the "actually" guy, but "contrary to popular belief, we do not have any skin preserved from megasloths: all the skin specimens we have stem from smaller ground sloth species" ( https://markwitton-com.blogspot.com/2019/10/megafuzz-under-microscope-how-credible.html ).

I think by "megasloths" he just meant the very largest of the ground sloths, so that apparently wouldn't include Mylodon (I see there's a size comparison of a bunch of genera in the ground sloth wikipedia article), since Witton does also say "fossil evidence shows that Mylodon was hairy", and London's Natural History Museum has a page showing preserved Mylodon skin and hair.

[BlueKrono]

I'm curious about Thalassocnus.