Therapod dinosaurs had primate-like numbers of neurons | Hacker News Reader

Therapod dinosaurs had primate-like numbers of neurons

biorxiv.org

69 pointsHooke41 comments

Here is a link to the actual article that allows you to download, print, and copy from the text. https://www.biorxiv.org/content/10.1101/2022.06.20.496834v1 It should probably replace the cloudflared, paywalled, and DRM'd wiley.com link.

Ok, we've changed to that from https://onlinelibrary.wiley.com/doi/epdf/10.1002/cne.25453. Thanks!

If they had so many neurons, then why did they all go extinct? Can't have been that smart.

But seriously, measuring volume to extrapolate density of neurons after a couple hundred million years of intervening evolution seems a bit tenuous, doesn't it? Also, this method wouldn't tell us what brain regions (neuroanatomy) nor their cognitive functions. So how smart they would have been relative to modern therapods seems still quite a large guess.

you seem to assume that we won't go extinct...

Or that was a facetious joke...

Therapods didn't all go extinct in fact. Survivors are called birds.

Recent and related:

The T. rex may have been smarter than previously thought - https://news.ycombinator.com/item?id=34331909 - Jan 2023 (24 comments)

  Competing Interest Statement
  The authors have declared no competing interest.

I'm sure it's just standard to have that on most if not all studies now, but I'm trying to imagine what a "competing interest" would be on a study like this. Easy to imagine if it's sugar or fossil fuels, but literal fossils? Is it possible to have competing interesting in paleontology? (I may not even be right about paleontology here)

If you happen to be a reptile you have to disclose that fact.

For example, a study could be enabled by a cool new product. Like a state of the art commercial computational technology. And one of the authors happens to hold stock in a company selling the product.

"Oh sh*t. This means turkeys have souls. Guess I need to get out of the livestock industry."

I’ll leave the Silurian hypothesis here:

https://arstechnica.com/science/2018/04/are-we-sure-there-wa...

Not only do we exist as a tiny island in the unimaginable vastness of space, but we also exist in a tiny present in an unimaginable vastness of time. Things that far back in time are like things orbiting other stars.

Who knows, maybe just a little more time and they would have shot down that rock.

I remember reading an article, linked from here, a couple of years ago, that stated, that, after just a couple of million years, the only evidence of our civilization, would be marbles. Everything else would be gone. Concrete, cities, steel, cars, roads, farmland, etc. All gone.

That infers that the dinosaurs could have had some kind of civilization, and there’s no evidence left, because they didn’t play jacks.

Wouldn’t there also be a particularly rich seam of rock with a high concentration of various minerals that we use?

I would think so. I tried finding that article, and couldn’t, but I did find this: https://news.ycombinator.com/item?id=16837120

It is called Silurian hypothesis eg https://www.cambridge.org/core/journals/international-journa...

PFAS would probably still be around. Nuclear waste too.

PFAS are called "forever" chemicals because they take thousands of years to degrade. In 65M years, they'll be gone. Same for nuclear waste.

If the dinosaurs had Teflon pans and nuclear power plants, we wouldn't necessarily know. The Himalayas didn't even exist yet when the dinosaurs were around.

We have evidence of a natural nuclear reactor from a billion years ago. Back then, there was a higher concentration of U235, and a uranium deposit with an underground river actually underwent fission. We can tell because the U235 is gone, and in its place are the daughter nuclides of the fission products.

https://en.wikipedia.org/wiki/Natural_nuclear_fission_reacto...

So it seems likely that our nuclear waste deposits will have isotopic concentrations that indicate fission took place. But this time, the U235 concentration is too low for it to have happened naturally.

I think the marbles in that claim are what the artefacts of civilization get crushed into rather than the only aspect of our civilization that wouldn't blend in with layers of surrounding rock.

If the eroded bones or even imprint of a soft body of some creature that waded in a swamp can be solidified into rock with sufficient fidelity to be preserved for many millions of years, the fossilised imprints and unusual mineral concentrations of the dinosaur equivalent of New York City would be hard to miss or dismiss, assuming it was somewhere we were looking.

It was not that. It was because the round shape discouraged weathering, and the silicate composition resisted any kind of chemical attrition.

A lot changes, in millions of years. A lot of what we think of as "the surface" was once underground. Entire mountain ranges rise up, sublimate, and weather, in millions of years. Continents drift around, etc. The Appalachian Range was once taller than the Himalayas. Mile-high glaciers once shaped the land (not that long ago, too). I live on glacier poop.

It's pretty hard to actually grok epoch time. My mother was a geologist, so I was raised with it, but it still boggles me, when I think of it.

It's entirely possible that we have seen "fossils" of artifacts, but don't recognize them, as such, because they have turned into rocks. We ignored fossils for most of human history.

Chips are silicon. Some of them almost have to end up in a future fossil record. In the future, scientist may speculate what kind of "soft shells" (plastic) the chips were surrounded by. :-)

Silicon isn't very stable.

Chips will make some very interesting fossils. They are basically an infinitely intricate pattern of class mixed with some stuff that will go away with time.

I find that hard to believe.

Manmade objects will probably disintegrate with time, but we have drained fossil fuel deposits, leveled down mountains, diverted rivers, drained lakes, etc.

Some of those geographical features will surely remain unnatural-looking (?)

In 65 million years? Nah.

Without opposable thumbs they didn't have anything that dolphins dont also have today

Hands are a very underappreciated part of human (individual & collective) intelligence. Evolution can't select for creative intelligence if there is no outlet for that creativity in the first place. Dolphins are probably much closer to human intelligence than we realize, but they have nothing to show for it because they're blubber torpedos with mouths.

> blubber torpedos with mouths

Stealing it…

My favourite dinosaur is Troodon it had a large brain for its body size. It may have been one of the most intelligent dinosaurs.

I read samples found showed that Troodons' brains were so big it left imprints on the inner part of their skulls.

It's interesting to think how it may have evolved over time if it had the time to do so.

I googled Troodon and the first result says it's "a dubious small bird-like Theropod". Is 'dubious' a technical term in this context?

From the Wikipedia article [0][1]

> In binomial nomenclature, a nomen dubium (Latin for "doubtful name", plural nomina dubia) is a scientific name that is of unknown or doubtful application.

[0]: https://en.wikipedia.org/wiki/Troodon [1]: https://en.wikipedia.org/wiki/Nomen_dubium

This paper starts by assuming that the different neuron density of birds vs non-avian reptiles is due to birds being endothermic.

That's... quite an assumption. EVERYTHING about the evolution of birds is about flight. Specifically, it's about keeping weight down. Loss of teeth, for example, is a tradeoff where birds have worse digestion in exchange for losing the weight cost of teeth. Birds frequently get leg injuries because of how small their legs are: again a tradeoff between durability vs weight.

Seems to me the first burden of proof for this theory is to show that birds have wildly more compact neurons due to endothermy rather than the usual weight issue. Their own data is not helpful to their point as it shows differences between bird clades suggesting significant evolution on this point since the initial evolution of birds.

I agree - it's interesting to contemplate but the article title should be Therapod dinosaurs _may_ have had primate-like numbers of neurons.

Clever girls.

Nice and teethy.

Not deserving being called "scary big lizard" at all.

Or maybe even scarier?

They may still eat you, but in a totally stylish and intelligent fashion. A Michelin star perhaps.

Very large animals usually have lower neuron densities than smaller ones, as I understand. Whereas birds in particular have to have very light brains so that they can fly. So I'm skeptical that a dinosaur had birdlike neuron densities.

What about crows and ravens?

From [1], ravens have ~2.171×10^9 neurons, roughly similar to dogs, raccoons, some monkeys, some parrots and birds of prey, an order of magnitude less than chimpanzees, which is a third of humans, which is a third of elephants. Whales aren't in this list, but they'd be more again (bigger body = more neurons needed to keep it functioning).

[1] https://en.wikipedia.org/wiki/List_of_animals_by_number_of_n...

Without referring to numbers, since I don’t remember them off the top of my head, I believe whales, generally speaking, have less neuron density (but usually higher absolute counts of neurons) than we do but actually have higher folding (gyrification) than human brains. Additionally, in whales, the relative size of the portion associated with emotional intelligence is much higher than that in humans.

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