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When Armor Met Lips

crookedtimber.org

519 pointsakkartik58 comments

Great photo selection with the shifty looking seal (gotta love the whites of caniform eyes) and a nice little summary of the article.

One thing about zoology and animal morphology is that we all know how important feeding is for animals but only real nerds love the digestive tract. Transport, skin, and reproduction are far more glamorous; but the mammalian sense of smell and mouth parts gave us such an advantage in the tertiary period.

It’s interesting that this sort of feeding never arose in the sea. I wonder what the ancestors of the pinnipeds who first ventured back into water ate…

If they're related to https://en.wikipedia.org/wiki/Mustelidae , probably just about any catchable animals?

Probably otter like to an extent. Would be interesting if the first thing they ventured into shallow seas for was ammonites though.

Parent was trying to make a joke about weasels being also shifty, but if ancestors of ppeds were like bears/otters, they would have gone for fish trapped in tidal pools then slowly acquired a taste for nautiloids which are easier to catch

If you find this evolutionary history interesting then I can't recommend PBS Eons enough. It's a great youtube series on the subject: well researched, a dense but breezy pace, and the paleo art + fossil images help convey information without being overly dry.

Here's the one about this subject: https://www.youtube.com/watch?v=3vQ55ToQeWI

"Pinnipeds evolved about thirty million years ago. They showed up first in the colder parts of the northern hemisphere, then in the Antarctic, then in temperate zones."

That's an interesting sequence, given that the continents then were about where they are now.

Maybe they evolved in both places independently, or maybe it took a couple million years for a pod of seals to make the journey from north to south, and then start dominating the local ecosystem.

Wikipedia says pinnipeds are monophyletic, so there's only a single evolutionary branch they originated from.

The travel question is much more interesting. Napkin math puts the distance between the polar circles at 12500 miles, the max swim speed of a seal at 25mph, giving a travel time of ~3 weeks of nonstop swimming as the crow flies. How does that happen? What would a pod of Arctic seals have eaten along the way, and what would have compelled them to make the trip out of familiar territory? How and why did they cross the temperate equatorial seas with a load of blubber?

Agree, this stuff is fun to imagine. Check out the many species that landed (and then kept evolving in isolation) in Hawaii. Seals, many birds, etc.

Look up monkey raft theory. How did monkeys from Africa get to South America? Also roughly 30 MYA.

Life travels on the ocean a lot farther than people realize, and often species you'd find improbably.

Ants spread around the world by hitching rides on coconuts or waterbirds. This now means there's something like a global war among various ant colonies that invade each other this way.

It's my understanding the ant spreading was more related with increase in navigation than birds/floating. that'd be why the Argentine ant has spread everywhere in Europe in the last century rather than being ubiquitous since the dawn of time.

I thought Wind, Wings and Waves to be a pretty interesting description of how species made it to Hawaii. Basically it either gets picked up in storms or large clumps of land make it across the ocean. Life only has to make the journey seldom or almost never and then take hold once to get to a new place.

Could an iceberg with a few seal families on it have drifted from the Arctic to the Antarctic? Presumably in the tropics the seals would have had a bad time and gone hungry and overheated, but once they got to cooler waters again, they would have been surrounded by food they love with zero competitors.

The distance is not surprising, animal trackers have shown they routinely travel vast distances in the ocean [1, 2, 3].

All you need is a fluke event, once in a thousand years where they for some reason make, and survive, this trip (I say thousand to give us some scale, could be actually once in a million years).

[1] https://www.ocearch.org/tracker/detail/nukumi

[2] https://www.ocearch.org/tracker/detail/dr-brent

[3] https://www.wur.nl/en/show/seal-telemetry.htm

Well the ocean was filled with free floating ammonites, so maybe food wasn't an issue. Another commenter suggests a volcanic winter to lower the sea temps enough for the seals to cross.

It is possible that they fed on extremophiles which thrived in really cold regions and later evolved to feed on other food sources.

It takes one volcanic winter for them to cross the oceans and emerge on the other side, without being fit for the warm waters.

That’s the sequence of notable populations; individuals did who knows what.

Do not neglect the Paper Nautilus, a kind of Mediterranean octopus.

https://www.sciencefriday.com/articles/the-seamstress-and-th...

https://www.themarginalian.org/2022/12/26/jeanne-villepreux-...

Jeanne Villepreux-Power invented marine biology, single-handed in the early 19th century.

She observed them repairing a hole in their shell by gluing on a found patch.

That is interesting. I looked it up on wikipedia and the Argonaut / Paper Nautilus "shell" is a thin walled eggcase and that males do not have. It does not provide protection.

Female argonauts have the shell their whole life long, and do not only construct it when they have eggs to put in it. We may reasonably assume that it has survival value even when there are no eggs. We know, for example, that they carry bubbles in it to tune their buoyancy.

I thoroughly enjoyed the author's writing style. Anyone know where I can find more by him, Doug Muir?

Google knows: https://crookedtimber.org/2024/01/03/welcome-to-doug-muir/

Normally a blog just lets me click the author's name and see more by them, and even the link you posted doesn't really show more essays.

This one did though: https://crookedtimber.org/author/doug-muir/

Thanks for the link, that's a worthwhile click - their previous article is great too: https://crookedtimber.org/2024/03/08/occasional-paper-the-ir...

"The Iron Snow Beneath Your Feet"

What a beautiful, poetic article. I learned something new, and saw the majesty of Earth's natural systems in a new light.

Personally I can't stand it, yeah?

> If you’re inclined to be pedantic about the nautilus’ limbs and say that /actually/ they are “arms” and not “tentacles” because tentacles have suckers on them, then (a) congratulations on remembering that long-ago biology class, and (b) see Footnote 1, above.

Something tells me an arm is a mechanical limb composed of connected poles that turn at their joints. And a hose-like limb without suckers should have its own name. A foot is an "arm", a penis is something else.

Hey, speak for yourself!

Penis is definitely something else because it contains (almost) no muscles, while your other examples do (contain muscles).

Also, tails

you don't need a new name, "tentacle" is fine and does not imply suckers. see hydra e.g.

Also: https://crookedtimber.org/2024/02/19/death-lonely-death/#com...

about Voyager 1, recently in the news

So the ideal tank buster is a carnivorous unicorn: penetrate that armor, then schlorp out the crew! Genetics will go too far, if we ever get these.

That's why the graceful, horse shaped unicorns of classical times died out; and what we have now is the up-armored, heavyweight rhinoceros version.

Evolution is amazing innit.

A fascinating case of how gunpowder has shaped biology.

Reminds me of one of my favorite Far Side cartoons https://www.reddit.com/r/TheFarSide/s/g5y9E0ZlmI

I wanted to go fossil hunting (and for ammonites in particular) after watching these guys just haul them out:

https://youtu.be/9XWhdPL58is

I really enjoyed this article, but I was really disappointed. For some reason I thought it was going to evolve into a Lovecraftian epic of how the grand and horrifying civilization of the ancient cephalopods and their relatives was thwarted by another species, one who paved the way for our own ignorant and doomed civilization to thrive.

I kept this feeling until the very end [spoiler] even when it was revealed to be seals I held out hope they could be a Lovecraftian player in a grand epic saga.

who do you think is protecting us from the lovecraftian horrors?

In general? Mostly ignorance. From cephalopods? I guess it's the seals

Italian love of calamari.

Paperclip counting bureaucrats of course

You might enjoy knowing that the name of one of the oldest known gods in Finnish history, one with very Cthulhu-style looks, came to mean walrus: https://en.wikipedia.org/wiki/Iku-Turso_(creature)

"So, you’re saying the nautiloids did okay until the pinnipeds sealed their fate?"

I'm nautiloid to say more about their spiral into the depths.

ಠ_ಠ

Never trust a pinnipedophile.

It is a shame that this is not about when Armour Meats perfected their hot dog formulation

"Ah! Love! The only thing my armor can't withstand!"

> geology nerd

Shouldn't that be "paleontology nerd?"

See footnote 1

Where is footnote 1?

I just looked up the authors of the article from their links at https://www.researchgate.net/publication/363885520_Seals_wha... and none mentions geology, though they did mention paleobiology, paleontology and fossils.

What did I miss?

The footnotes for the article are in the first comment. The author put a humorous footnote about being pedantic.

And, in doing so, was pedantic!

https://www.google.com/search?q=pedants+revolt

"I'd expected there to be less of you." "FEWER!!"

Paleontology used to be a subspecialty of geology, for a long time after they proved fossils had once been animals. Which the geologists had to do.

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