Half-billion-year-old sea squirt could push back origins of vertebrates

July 6, 2023 11:54 PM

Half-billion-year-old sea squirt could push back origins of vertebrates, including humans.
posted by chariot pulled by cassowaries (13 comments total)

my grand ^4562500000 dad!
posted by Heywood Mogroot III at 12:59 AM on July 7, 2023 [6 favorites]

Tunicates! They are amazing, to me--I just learned of their existence a few months ago, or, I should say, learned they were something really really different than all the little anemones and things that vaguely look like them, and spent days reading about them and looking up more and more species of them. They're in our phylum, Chordata, and when you see them you wonder, how on earth? What are they doing there next to vertebrates? Some of them are really, really gross, and some kinda bloop around the ocean and glow! If you find yourself wanting to dig into how interesting they are, here's a great introduction to them!
posted by mittens at 4:56 AM on July 7, 2023 [6 favorites]

From mittens' "really gross" link: Almost all the tunicates contain at least one worm.

In another few million years the worms will just be an organ in a new, more complicated species of tunicate. Nature is just so appalling, but yet also amazing.
posted by seanmpuckett at 5:45 AM on July 7, 2023 [4 favorites]

Half-billion-year-old sea squirt could push back origins of vertebrates

For a moment I had a mental image of a very tired, very wrinkled sea squirt slowly pushing a book back into a shelf and rescheduling a biology lab because they’ve just had enough for this aeon and it can wait.
posted by mhoye at 6:05 AM on July 7, 2023 [17 favorites]

This is interesting and I am also a tunicate fan. One thing that confused me was the statement that "But only a handful of tunicate fossils exist, for reasons paleontologists can’t fully explain." I suppose that is technically true, but isn't the main and obvious reason the fact that they are entirely made of soft tissue that doesn't fossilize frequently?
posted by snofoam at 7:28 AM on July 7, 2023 [3 favorites]

I guess there must be even fewer fossils than they've found for other organisms that you'd think would fossilize similarly often.
posted by BungaDunga at 8:15 AM on July 7, 2023 [1 favorite]

Rare fossil "looks like it died yesterday"

That's also what people say about me, heey!
posted by bigendian at 8:28 AM on July 7, 2023 [6 favorites]

I don't get the logic re vertebrates: seems to be akin to saying that if your sister is 50 years old, that's how old you must be too?
posted by splitpeasoup at 8:50 AM on July 7, 2023

I think it's saying that if your sister is 50 y.o. then your parents (common ancestor) have to be at least x years old, and that's the age that is possibly being pushed back.
posted by OHenryPacey at 9:31 AM on July 7, 2023 [2 favorites]

Why the hell was this locked up in a desk drawer in Salt Lake City all this time?
posted by BostonTerrier at 9:48 AM on July 7, 2023

So my heart once evolved from a sea squirt like creature? The resemblance is striking.
posted by polymodus at 10:37 AM on July 7, 2023 [1 favorite]

"But only a handful of tunicate fossils exist, for reasons paleontologists can’t fully explain."

Maybe they were delicious?
posted by Capt. Renault at 10:54 AM on July 7, 2023 [1 favorite]

Good ol' sea squirts! In middle school, I spent a summer at Duke's marine lab in the Outer Banks and, being dumb 13 year olds, we used a tank of seq squirts as waterguns. Because they filter feed on bellies full of water, if you pick one up and tickle it, it will, well, squirt. If you're lucky, it's relatively clean-looking water. But if it's been digesting for a while, you get a nice green spray of sea squirt shit. Good times, good times.
posted by thecjm at 11:44 AM on July 7, 2023 [1 favorite]