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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Humans killed them. They were threats. The invention of the spear and throwing basically kills any large animal, along with digging pits.
Even if a predator manages to kill human hunters, it won’t get away uninjured, and eventually those injuries will cause complications.
Ok so first… sauropods. Yeah they really were special when it comes to their size. Nothing before or since has ever come close when talking about terrestrial animals. As far as we know, they could hit around 70 tons! A combination of the shape and build of their legs, in combination with air sacks running through much of their body to cut weight allowed them to support themselves.
But beyond that, dinosaurs were not larger than mammals. The 2nd heaviest terrestrial group of animals were elephants, with some species reaching over 20 tons. The 3rd heaviest group was rhinos, with paraceratherium also reaching close to 20 tons. Hadrosaurs come in a distant 4th place at 14-16 tons as far as we know. 5th and 6th seems to be up in the air between ceratopsians and theropods.
The largest recorded african elephant is close to 11 tons, which puts it up there with the largest theropods in weight.
But generally prehistoric animals were larger, and this includes prehistoric mammals. This is due to a combination of a cooling and drying climate over the past 10 million years, followed by human evolution and overhunting. Many megafauna were already in a bad way when humans arrived, which drove them to extinction.
For vertebrates, I think the limiting factor is usually availability of food. Being big requires a large energy intake. Life is not as abundant today as it was back then (remember we are still technically in an ice age). It’s not so evolutionarily advantageous to be huge.
Humans killed them. They were threats. The invention of the spear and throwing basically kills any large animal, along with digging pits.
Even if a predator manages to kill human hunters, it won’t get away uninjured, and eventually those injuries will cause complications.
Ok so first… sauropods. Yeah they really were special when it comes to their size. Nothing before or since has ever come close when talking about terrestrial animals. As far as we know, they could hit around 70 tons! A combination of the shape and build of their legs, in combination with air sacks running through much of their body to cut weight allowed them to support themselves.
But beyond that, dinosaurs were not larger than mammals. The 2nd heaviest terrestrial group of animals were elephants, with some species reaching over 20 tons. The 3rd heaviest group was rhinos, with paraceratherium also reaching close to 20 tons. Hadrosaurs come in a distant 4th place at 14-16 tons as far as we know. 5th and 6th seems to be up in the air between ceratopsians and theropods.
The largest recorded african elephant is close to 11 tons, which puts it up there with the largest theropods in weight.
But generally prehistoric animals were larger, and this includes prehistoric mammals. This is due to a combination of a cooling and drying climate over the past 10 million years, followed by human evolution and overhunting. Many megafauna were already in a bad way when humans arrived, which drove them to extinction.
For vertebrates, I think the limiting factor is usually availability of food. Being big requires a large energy intake. Life is not as abundant today as it was back then (remember we are still technically in an ice age). It’s not so evolutionarily advantageous to be huge.
Ok so first… sauropods. Yeah they really were special when it comes to their size. Nothing before or since has ever come close when talking about terrestrial animals. As far as we know, they could hit around 70 tons! A combination of the shape and build of their legs, in combination with air sacks running through much of their body to cut weight allowed them to support themselves.
But beyond that, dinosaurs were not larger than mammals. The 2nd heaviest terrestrial group of animals were elephants, with some species reaching over 20 tons. The 3rd heaviest group was rhinos, with paraceratherium also reaching close to 20 tons. Hadrosaurs come in a distant 4th place at 14-16 tons as far as we know. 5th and 6th seems to be up in the air between ceratopsians and theropods.
The largest recorded african elephant is close to 11 tons, which puts it up there with the largest theropods in weight.
But generally prehistoric animals were larger, and this includes prehistoric mammals. This is due to a combination of a cooling and drying climate over the past 10 million years, followed by human evolution and overhunting. Many megafauna were already in a bad way when humans arrived, which drove them to extinction.
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.
For vertebrates, I think the limiting factor is usually availability of food. Being big requires a large energy intake. Life is not as abundant today as it was back then (remember we are still technically in an ice age). It’s not so evolutionarily advantageous to be huge.
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.
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