Hacker News Reader

As far as I understand, keeping such creatures alive would require facilities with enriched oxygen. If the large ones escaped, they would suffocate.

"...large dinosaurs really required to be living in an oxygen tent. An atmosphere in the neighborhood of 35 percent oxygen would be considerably more compatible with large dinosaurs than one in the neighborhood of 28."

Volcanic activity in the Cretaceous enabled these high oxygen levels.

"The Cretaceous is clearly a green house period as opposed to the present ice house that we have... One of the problems that people have always suggested about these high levels of oxygen at various times in the past, is that this is comparable to what you have in an oxygen tent in a hospital. And what about wildfires? What they forget is that the reason for this high oxygen is that there is also a high carbon dioxide level. We are talking about carbon dioxide levels 6 to 10 times the present carbon dioxide level. And that is more than enough to essentially combat wildfires."

https://profjoecain.net/wp-content/uploads/2018/06/robert-e-...

Oxygen only one part and for all we know there were other trace gasses in the air they required that we don't even know about.

There are all kinds of animals today we cannot keep alive in captivity because they require some sort of unknown sequence of environmental triggers to activate or deactivate various processes in their body.

For instance cheetahs are nearly impossible to breed in captivity because their mating process requires running for many miles to exhaustion. Without this the pregnancy rate is in the abyss even with artificial methods. There are endless examples thats just one off the top of my head.

We just need to create a cheetah racing league. Problem solved.

Makes me wonder what the evolutionary benefit of keeping such triggers are and makes me wonder if part of the reason for the drop in human fertility in parts of the world is due to us removing some of those triggers for ourselves.

Hmm… I have a question inspired by your choice of phrases:

Is there a graph somewhere of Earth's mean sea level atmospheric pressure over time? Was it significantly different e.g. a billion years ago?

On mobile so I'll let other ppl sezrch. My $0.02: atmos pressure is a resultant of gravity, which is a result of mass.

The mass has reduced over time, due to solar wind blowing away our atmosphere. But compared with the mass of the friggin' earth, my intuition says atmos pressure has reduced only slightly

I see where you're going with that, but gravitational force is GMm/r^2, so the mass of the air column halving would halve the pressure, and the shell theorem implies that is exactly half and not even a rounding error on M because none of the air above (the only bit contributing to the pressure) can contribute to the gravity field.

First part is also why Venus, with a lower mass, is able to have about x89 Earth's atmospheric pressure.

This doesn't directly answer your question but adds some interesting context. Some dinosaurs shouldn't be able to fly in the current atmosphere:

https://lru.praxis.dk/Lru/microsites/hvadermatematik/hem1dow...

Luckily they evolved feathers and manage just fine.

They had feathers when they were dinosaurs, and they’re smaller now.

I can’t usefully comment on most of the actual science in that paper, but I already had reasons to expect significant changes to the total mass of the atmosphere before reading it — the difference between today and the pre-oxygen apocalypse era (~2.4 Gy) implies at least a change of either 0.21 bar (if the oxygen came from the water) or 0.07 bar (if it all came from CO2).

I have no idea what to also anticipate from geology, impacts, or other things life might do besides the GOE.

When they were feathered dinosaurs, though, they couldn’t fly.

Both unclear[0], and also given the end of that sentence, unimportant.

[0] https://en.wikipedia.org/wiki/Archaeopteryx#Flight

Why would a 2% CO2 atmosphere combat wildfires? It's a non-reacting gas, but so is nitrogen... And yet, wildfires still happen, despite our 79% nitrogen atmosphere.

Venus has a CO2 atmosphere, so the upper bar is very high.

While it is true that there are no wildfires on Venus, there is also no wood, or oxygen. Any oxygen released immediately reacts with the dirt to make, largely, more CO2.

If you wanted to terraform Venus, you would need to make diamonds out of the air so the carbon wouldn't just burn again. The oxygen you release would then react with the dirt and rocks to make more familiar minerals, and more CO2, of course. For a long time.

The whole surface would be a mile deep in diamonds before you finished. Hardly any water: the solar wind, not deflected by a magnetic field, carried most of that off. She probably had a field when she still rotated fast enough.

Earth gets to keep her water because the moon keeps us rotating enough to keep a magnetic field. Mars lost his because he is too small to keep a liquid core to generate the field with.

Yeah, I was pointing out that atmos can store a ton of CO2, past a certain point life be damned. Our lungs only work on the differential in the air lower to our body's.

Wait, why would carbon dioxide levels have any effect on wildfires more than, say nitrogen?

For wildfires, I would expect the proportion of oxygen to matter much more than other gasses not involved in combustion.

Perhaps there's a difference in humidity levels, and therefore specific heat of the air?

Nitrogen is inert. Combustion doesn't need nitrogen. It just basically fills space.

As far as wildfires go, so is carbon dioxide. CO2 is not a typical reactant of combustion.

Sure it does, it's a "product", so in principle it participates in the reverse reaction. This probably doesn't actually make a difference for combustion, although CO2 does apparently work a bit better than N2 for firefighting in spite of the added weight, but that seems usually attributed being heavier-than-air (heavier than O2!) and somewhat polar. Not sure how applicable that is to wildfires when it's the atmosphere, though.

Well, maybe, but humans can live at altitudes with about to half our normal oxygen levels, so maybe dinosaurs would have similar tolerances.

Humans tolerate those altitudes very poorly. They suffer from health problems and miscarriages.

High-altitude genetic adaptations have been the subject of a fair amount of study; there are three major groups bearing such adapations: Tibetans, Ethiopians, and Andeans.

The Andean adaptation suite is noticeably more primitive and lower-quality; this is generally thought to be the result of having evolved only very recently, after humans made it to the Americas.

The Tibetan suite is so effective that part of it has been proposed to be the result of interbreeding between arriving homo sapiens and a different hominid species native to the Tibetan plateau.

Thanks. I didn't know Ethiopians were also in the altitude mutant club!

My anecdote is I travelled in Bolivia for 3 weeks. Never under 3700 meters. One day we climbed Uturunku (6008 meters) as part of a jeep tour, You start at 5100 meters, so it's less crazy than it sounds.

Of the 6 tourists starting, only 3 made it up, with some real struggles.

Meanwhile, our native guide seemed to just have a relaxing walk...

Humans are really exceptional in their ability to survive in a large range of environments. If you do some reading about just how fragile many if not most animals are in regards to their environment you will surprised that they exist at all.

"Basically if we bring back dinosaurs it will be to torture them for our amusement and curiosity". Just a thought experiment, I hope I won't be downvoted to hell. Isn't this the predicament of all beings? You might say, that some people enjoy life, but at that point you should

1) Confirm that all beings are not answering with a Stockholm Syndrome

2) Confirm what is the subjective experience of the dinosaur

I have neutral or positive emotions most of the time, and negative emotions only rarely. I almost never have negative thoughts (anymore).

You hit me with Stockholm Syndrome; I respond with Typical Mind Fallacy. Just because your life is largely suffering, you assume that all humans lives must largely consist of suffering. This is not true.

If the Antarctic thaws, it would be probably the best place for them.

I was not talking about purpose.

I meant that dinosaur are not biologically capable of living in this time period or this environment of earth. They would have to be on life support from birth. Even than it would take many years of trying before we figured out how to keep them alive. Which means they would start dying a slow agonizing death from the moment we create them.

It would be like dropping people off on Venus and saying make the best of the sulfuric acid atmosphere.

Have you ever seen a killer whale in captivity with its top fin floppy/not standing up straight. They have no idea why that happens in captivity they cannot figure out even after many decades of them being captive. Now imagine that with millions of years of difference.

Pretty unlikely that we would be able to find a complete DNA of a single species of dinosaur. More likely we would have to patch it together and while we're at it might as well modify it allow them to survive under current conditions. Just speaking hypothetically here but that seems like the more probable scenario.

It seems like more than an issue of DNA to create a 50 ton dinosaur that could survive in a modern climate. Dinosaurs were able to reach their sizes precisely because of the oxygen-rich environment, not just their DNA.

So we make small dinosaurs?

What about not bringing back dinosaurs but changing the dna of say a chicken to resemble that what we'd consider to be a dinosaur without it actually being any historically known dinosaur?

A generically modified chicken won't help us. We're going to need actual full-blooded dinosaurs if we ever hope to find out how they built Stonehenge.

this sounds like the way, actually this is how it work in book. I think this will happen.

That seems more plausible to me too, that we'd actually end up with something "based on actual dinosaurs!", maybe even with "Motel of the Mysteries"-type historical misconceptions baked in, just to make them meet expectations.

Life.. uh.. finds a way

True, if we bring back dinosaurs, that will be the biggest example of it

Google searches for "high altitude dinosaur" mostly find complaints that scientists assume they exist but mountains are peak erosion sites so there are no fossils or other evidence.

Theoretically geologists could predict high altitude plains or areas of generally high ground, probably, and it would be interesting to see reported fossils in those known lower PP-O2 areas. Fossilized vegetation evidence in the area of dino fossils could indicate higher altitude for both.

Sure, intuitively most dinos would thrive in hot swampy jungles. But there's so much delicious higher altitude land covered in pine trees waiting to be eaten... The cold argument is serious, but plenty of animals migrate, so given great forest of edible food, something should have evolved to eat its way uphill in the summer ...

Life "finds a way" by evolving adaptations. Not by running obsolete technology in an inappropriate environment.

Life has found a way - we are it!

Until life finds another way, which at this rate will probably be some kind of fungus.

It has. They're called birds.

Yeah, they need to place theses jurassic creatures in a park on an island somewhere.

I mean, what could possibly go wrong?

Yes, my thought exactly. The oxygen level in the air was significantly higher and there is no way some of those larger dinosaurs could exist without much higher oxygen content.

birds are dinosaurs. I’m not sure how much they evolved from their ancestors but I don’t think it’s much. If I were to guess Dinosaurs will live fine on the current earth.

They had millions of years to evolve.

So did many other organisms who are still with us today. I'm guessing most organisms will be fine if the basics are covered (tolerable level of oxygen and air pressure, tolerable levels of radiations).

Evolution doesn’t work by having individual creatures keep calm and carry on just ‘putting up’ with whatever geological, climatic or atmospheric changes take place.

Evolution works by having creatures that can’t handle the new situation die. Preferably before they are able to reproduce.

And it may have escaped your attention, but the large non-avian dinosaurs? They all died out.