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Comment by kyleee | Hacker News Reader

How did they die together like that?

Good question. Given they were found in a dried riverbed, my guess is they were caught in a flash flood. The armour made them move slowly and they couldn't run fast enough.

If they were caught in a flash flood the odds of all of them ending up together seems very low just from my experiences with flash floods in the Sonoran desert. Flash floods are VERY violent and will take 2-4 ton vehicles and throw them about like a tiger playing with a mouse. Those remains don't look like they weight that much so I would think some other, less violent, event led to them all expiring near one another at the same time.

20k years ago the flash floods were less evolved and hence were much slower than the modern newfangled flash floods you're talking about.

Flash flood is the modern species. They were splash floods back then, until dash floods emerged, leading to the modern variety as speed increased even more.

Are these all AI generated jokes?

Nah, just out-of-practice, work-from-home dad jokes (at least GP, which was mine)

As the flood dissipates downstream particles will fall out of suspension and/or wash ashore. They're all the same shape and density so the conditions in which they drop out is going to be about equal. If they were all swept up from the same starting point they could very well all end up washing up in the same place. It's made more likely if the river has something like a natural lake for the flood to dissipate into. The dead stuff is free to float about and get naturally sorted by the wind and mild currents.

There's further evidence for flash flood (or mudslide?) though: IIRC, they need to be buried very quickly and thoroughly for fossilization.

Not sure that's how it works. I think the river/streams while changing it's course exposes the fossils.

I've never found an entire glyptodon but I have a couple of pieces of the shells that I found while fishing in small streams. There's one stream in which you almost always find some piece.

I'm sure in that same stream there must be some entire shells because some of the plates I found aren't eroded at all, which indicates that it didn't move much from where the rest of the shell is.

> Not sure that's how it works. I think the river/streams while changing it's course exposes the fossils.

That gives me another hypothesis, about how they died together. Some of those critters dug burrows, we still find those today[1]. It's likely sometimes those burrows caved in, entombing its inhabitants. Perhaps they were sheltering in their burrow, and died together when it caved. Then their remains spent thousands of years undisturbed underground, until the river changed course, exposing them.

> I've never found an entire glyptodon but I have a couple of pieces of the shells that I found while fishing in small streams.

Giant sloths had these bone plates under their skins as well (both sloths and armadillos belong to the order Xenarthra[2], together with anteaters), some were even found with evidence of being used as pendants by paleoindians[3].

[1] https://revistapesquisa.fapesp.br/en/shelter-for-giants/

[2] https://en.wikipedia.org/wiki/Xenarthra

[3] https://news.ycombinator.com/item?id=41520020

Didn't know about the sloths but osteoderms from glyptodons are quite different.

Maybe it was like Alaskan mudflats and the animals got stuck or sucked in. If that's the case, maybe it's possible they didn't die together.

Maybe they had freeways and Chevy Suburbans like in Texas.

But an interesting thing I've read is that armadillos breed in identical multiplets for some reason, so they may all have been babies of a single brood.

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