Comment on Bring them back!!!
argh_another_username@lemmy.ca 3 days agoI read somewhere that if we could bring back a dinosaur, it wouldn’t survive long, because of the oxygen concentration in our atmosphere. Is it true?
I may have heard a similar thing on a video that compared an elephant sized mouse with a mouse sized elephant.
Neither could survive because evolution designed their bodies for the relative pressure they exist in. This is also related to how fast their hearth beats go.
Human sized bugs could not exist for the same pressure reason also.
Disclaimer: i am as much an expert on this as are you. Source is the internet. Possibility Kurtzgesagt.
Depends. Something from 125 to 200 millions years ago would probably struggle. Maybe you can put them on a mountain? But that’s probably too cold. But again, Jurassic Park dinosaurs are a mix of animal DNA, contemporary and older.
LifeInMultipleChoice@lemmy.dbzer0.com 3 days ago
I think that has a lot of variables. Crocodiles were on earth around 250 million years ago, the t rex around 68 million years ago. Crocodiles still breath our atmosphere.
That doesn’t mean other animals didn’t have different breathing parameters though.
otter@lemmy.ca 3 days ago
Crocodiles may have also adapted over time to deal with the changes in our atmosphere, while the dino DNA would not have gone through those changes. They could handwave that problem by saying they combined it with some other DNA or modified it themselves (better hemoglobin?)
LifeInMultipleChoice@lemmy.dbzer0.com 3 days ago
Was curious so I tried to find historical Oxygen levels by century. With the current oxygen level being around 20.9% and decreasing to effectively 17% around a mile in altitude, (say Denver) we adapt to 4% oxygen level without death. So if dinosaurs are similar in breathing to humans, I’d say with no scientific backing beyond just speculation, they should be fine.
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leftzero@lemmynsfw.com 3 days ago
Current living dinosaurs are much more efficient at extracting oxygen from air than practically anything else in the planet.
Birds’ve got a unidirectional respiratory system that ensures oxygenated air is constantly flowing through their lungs (unlike, for instance, us mammals, who must empty our lungs of spent air before we can fill them again), and a system of air sacs to keep the air constantly flowing.
While fossil records of the earliest dinosaurs show no evidence of air sacs, later ones do, suggesting that bird-like respiratory systems evolved multiple times in parallel in different branches.
Sauropods in particular might have had even more complex air sac systems than modern birds, which could explain how they managed to grow so large (i.e., they were full of air, and might have been even more efficient when it comes to breathing, though their long necks might have offset the balance in the opposite direction).
Dinosaurs would have been perfectly fine with current oxygen levels.