Dinosaurs seemed to have generally been so much larger than animals today. Huge dragonflies that dwarf their modern counterparts, turtles 10ft long. What is the mechanism that allowed them to be so large, or conversely makes modern ones smaller? Is it about Oxygen levels, or efficiency, or something else?
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We used to have plenty of megafauna, most of it went extinct fairly recently. mammoths, giant ground sloths, direwolves, giant elk are only a couple of examples. I believe some were hunted by humans (mammoths), others fell victim to the changing environment. The last ice age wasn‘t too long ago (technically it‘s still going on) and the largest and most specialized animals are always the first to die out, because they‘re just not as flexible as others. The ecological niches filled by megafauna are now mostly empty. give it enough time and animals will evolve back into their gigantic selves but that‘s not yet the case.
Also I think terrestrial mammals can‘t get as obscenely huge as dinosaurs because of a difference between the way mammals and reptiles work but I‘m unsure what it was.
Survivorship bias. There were dinosaurs that were lizard, chicken, and dog sized. Fossilization takes a unique set of circumstances and a long time to replace the minerals in the bones. Large bones are more likely to survive the process. Additionally larger bones are easier to find. A farmer will notice when he breaks his plow on a femur as tall as he is, from a creature as long as a city bus, where smaller bones might just get churned into the soil.
As for the ones that did get big, being large is a good defense. Look at modern megafauna, like elephants and giraffes, for most predators the hide is to thick or the important bits are too far out of reach. It would take a cooperative hunt from large predators, in desperation, to have a slight chance.
Survivorship bias. There were dinosaurs that were lizard, chicken, and dog sized. Fossilization takes a unique set of circumstances and a long time to replace the minerals in the bones. Large bones are more likely to survive the process. Additionally larger bones are easier to find. A farmer will notice when he breaks his plow on a femur as tall as he is, from a creature as long as a city bus, where smaller bones might just get churned into the soil.
As for the ones that did get big, being large is a good defense. Look at modern megafauna, like elephants and giraffes, for most predators the hide is to thick or the important bits are too far out of reach. It would take a cooperative hunt from large predators, in desperation, to have a slight chance.
Survivorship bias. There were dinosaurs that were lizard, chicken, and dog sized. Fossilization takes a unique set of circumstances and a long time to replace the minerals in the bones. Large bones are more likely to survive the process. Additionally larger bones are easier to find. A farmer will notice when he breaks his plow on a femur as tall as he is, from a creature as long as a city bus, where smaller bones might just get churned into the soil.
As for the ones that did get big, being large is a good defense. Look at modern megafauna, like elephants and giraffes, for most predators the hide is to thick or the important bits are too far out of reach. It would take a cooperative hunt from large predators, in desperation, to have a slight chance.
Earth’s gravity was not as strong millions of years ago. If those big dinosaurs lived today, they would be crushed by their own weight. As the universe continues to expand , stretching the fabric of space, the forces applied to any object deforming that fabric ( like a planet ) increase.
Earth’s gravity was not as strong millions of years ago. If those big dinosaurs lived today, they would be crushed by their own weight. As the universe continues to expand , stretching the fabric of space, the forces applied to any object deforming that fabric ( like a planet ) increase.
Earth’s gravity was not as strong millions of years ago. If those big dinosaurs lived today, they would be crushed by their own weight. As the universe continues to expand , stretching the fabric of space, the forces applied to any object deforming that fabric ( like a planet ) increase.
Dinosaurs specifically had spines that “scaled well,” I forget the specific mechanism but it let them get much larger than the theoretically largest mammal.
My unprofessional take is that the big dinosaurs died because they couldn’t adapt as well to the rapidly changing conditions compared to the smaller flying ones during the last mass extinction. Most of the big mammals are gone because we ate all of them or changed their ecosystems. Some of them are still around though, like whales.
Also fossil record goes back a very long time, so it might also be a kind of a selection bias. There might be many giants in the making at the moment but they just haven’t got there yet.
Dinosaurs specifically had spines that “scaled well,” I forget the specific mechanism but it let them get much larger than the theoretically largest mammal.
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