40

I propose a Frame Challenge In reality, herd animals are frequently found in meadows and large open areas despite eons of hunting, which, presumably, would lead to the animals that survive being those that were more likely to stick to the trees. The problem is that herd animals need a ton of grazing space — which is very difficult to find in forests. Add to ...


38

Cephalopod strangeness: I don't think this is very probable, but strange things happen. The most likely scenario I can think of is that an octopus has evolved to moving on land, and they are using actual skeletons to frighten the apex predator (humans) away. Heikegani crabs are believed to have a survival advantage because their shells bear a resemblance to ...


37

How about neither? Tetrapods evolved straight from lobe-finned fish; essentially no-limbs to four-limbs. You could have a similar process, except when the fish were developing limbs they ended up with six instead of four. This would probably give you six-legged amphibians; I would expect six legs before four-legs-and-wings. However, if you wanted to throw in ...


31

Grasslands already prevent forests through the tolerance of grass for fire. Grass is not ancient. In many areas, the evolutionary master stroke of grass that klet it take over large parts of the world is that it can tolerate fire by hiding its biomass underground. By tolerating (and encouraging!) fire, grass can outcompete taller plants that would shade it ...


25

I don't see how they could go straight from underground to space. They would first have to (at least partially) re-conquer the surface. Using the surface could be very interesting for them, as transport is much cheaper. Of course you need protection there, so a first milestone could be some sort of automated surface train. This could be connecting ...


19

Yes, but not from radiation. The Earth has witnessed plenty of giant, terrifying insects over its 4.6 billion years. During the Caboniferous period, well before the dinosaurs, there was slightly more atmospheric oxygen, because oxygen production was outpacing the capacity for photosynthesis to remove it. As a result, dragonflies grew to be the size of ...


16

Pleomorphic Dragons and Monsters: Rather than trying to justify something in the normal way that is so controversial, let's propose a new thing all together. What if the ancestors of dragons and other monsters developed in a new but not unheard of manner? What if all dragons are a form of conjoined identical twins? Identical twins exist, as do conjoined ...


16

I'm going to go ahead and say its not possible without being a 100% magical construct. Sufficiently advanced technology probably will be able to make skeleton size and shaped robots that meet your criteria, but I don't think biology can. Take a look at the various groups that use exoskeletons: insects, arachnids, and crustaceans. They are mostly quite small ...


15

Those Sizes Sound Manageable The coconut crab can grow to about one metre. Seems it has overcome the main limitations like heavy carapace and inefficient respiratory system. Whatever evolutionary tools the coconut crab has, your giant insects have evolved analogous tools. Realism: Coconut crabs aren't fast. For realism your insects should be much slower ...


15

they can perceive their surroundings by using ultrasounds (like our bats), and a powerful capacity to smell minerals and all types of molecules. None of those abilities will make them aware that there is something called "space" above their heads. What is current space science started when some humans started looking up in the sky and noticed the ...


14

It's called selective breeding, and humans have been doing it about as long as they've had domesticated animals. (And plants too, but you just ask about animals.) Perhaps the best example is the dog. The ancestral wolf has been selectively bred into hundreds if not thousands of different varieties, ranging in size from Chihuahuas and Pekinese to St. ...


12

Since this is for Anatomically Correct, I'm going to assume a technological basis rather than magical. Of course Clarke's Third Law remains true, and so does its inverse, so implementing the concept is "left as an exercise for the reader"; pick whichever method works for you. Mechanical bodies Starting from the extremities, a skeleton clearly has ...


11

Lots of vertebrates reproduce asexually, with this being the preferred or only form of reproduction for many lizard species. You can find out more about this on the Wikipedia article about parthenogenesis: Most reptiles of the squamatan order (lizards and snakes) reproduce sexually, but parthenogenesis has been observed to occur naturally in certain species ...


10

Reusing part of my own answer to another question: When DNA manipulation techniques were yet to come, and scientists wanted to explore genetic mutation, they had to use something similar to what you depicted. They applied this method to developing new plant variants. How did it work? They placed a gamma emitter in the center of a circular field, then planted ...


10

I'm assuming they've got access to their recorded history and know about the time when they were on the surface, or have noticed something unusual (eg gravity waves) and want to go check them out. Basically they know space is there and want to go there. I see a few paths: They find the Star Gate or a buried crashed alien ship, or some other peice of ...


9

Burning down all the forest is a massive investment for uncertain return. If you burn down more than you need, another dragon may move in and exploit your effort to feed itself to your active harm as it's a competitor. And destroying forest is a never-ending battle. You end up with trees that NEED to be burned to sprout. There are grasslands. Hunt there. ...


8

For ants, specifically, plausibility in biology aside, where there's one ant there are thousands more. Plus ants work together. I'd take any of those other giant creepy crawlies over giant ants any day. I don't think an ecosystem could support that many ants unless they do it the same way people do: take over the land, cultivate, and concentrate resources in ...


8

Forest fires are a natural part of the cycle in their own right. There's a selection of pyrophilic trees around the world, many requiring fire as part of their reproductive cycle. Though the eucalypts could be considered more pyromaniac than pyrophilic, effectively taking the place of your dragons in deliberately starting fires. A planet that has evolved ...


8

They are a divergent evolutionary branch of homo sapiens, to be more precise of the homo sapiens subspecies toppus modellus. At the times around the transition between 20th and 21st century, a particular variant of humans were highly priced in the current society. These humans were called model, and their salient physical feature was being really skinny. ...


8

I'm going to presume that there is still bacteria. You need something to break down dead plants and release carbon. Otherwise all the carbon gets locked into the forest floor and plant growth dies for lack of carbon. Pollinating Plants There could still be pollinating plants. They would just depend on wind instead of animals to transport their pollen. Many ...


7

Your best bet is to have an early magical event that creates a 6 limbed lizard, that can evolve into the other 6 limbed forms you need. repurposing unused limbs is pretty common evolutionarily speaking, so it can evolve into whatever else you need. Consider using something from Sauria they evolved a wide variety of forms (crocodiles, dinosaurs, birds, ...


7

Water holds much less oxygen than air This is why gills are such fragile delicate things. The amount of oxygen absorbed scales roughly linearly with two variables. One, the concentration of oxygen in the medium it wants to absorb from. And two, the area of the exchange surface (as the rate is approximately constant per unit area). So gills need a much ...


7

Because it’s there This may be a bit of a cop out, but just because biology dictates they be subterranean doesn’t mean they can’t be curious about other environments. Humans aren’t made for living deep underwater, and yet there are sub nautical observatories. If these creatures view things via echolocation they have a concept of far distance and such. They ...


7

"perspiring through the skin (something that apparently only mammals do; correct me if I'm wrong) " If you define perspiration as squeezing liquid water our via the skin... many things do that. Many Mammals, amphibians, snails, some TREES, etc.. If water contact with the air or dust forms acid, your inhabitants should stop breathing. Because the ...


6

Evolution is not a predetermined path where from A follows necessarily B. It follows the laws of probability: random mutations happen all the time in a random fashion, if they happen to giving their bearer an advantage they are promoted in the life lottery. Look at sharks and dolphins: they show that in at least two cases a similar hydrodynamic profile has ...


6

They started at six limbs. I have read a manga -Centaur no Nayami- where evolution went a road where terrestrial creatures had six limbs, to justify centaurs. But it checks out! if there were 6 to begin with, two of them can become wings, and if you don't want the rest of your fauna to have 6 limbs, they can become vestigial members and disappear visually. ...


5

We have common ancestors with arthropods. The reason why we grow large and they don't is because we evolved ways to scale better to large sizes. We don't molt and we have breathing organs with a much greater ratio of surface area to volume. Some spiders and scorpions have book lungs, which are not as efficient as our lungs, but which outdo insect tracheas. ...


5

Evolution tends to be very conservative when it comes to creating completely new body parts, but very creative when it comes to reusing and adapting body parts. So rather than starting with a smaller set of limbs and gaining new ones, think about starting with a different combination of limbs, and then specialising them. An interesting comparison here are ...


5

They are not smart enough Your dragons are not smart enough to make the (very long term) connection behind burning down a forest and having a better food source. After all it takes months or years before the burned wasteland of a forest turns into a meadow. This is entirely believable since humans are the only animals that can think ahead such a long time. ...


4

Translucent fungus This is a slight cheat on your condition that there be no visible muscles or ligaments, but imagine something similar to a slime mould, that has colonised the skeleton of a deceased human. I specify translucent because in low light, it would look mostly like just a self-moving skeleton. In real life, slime moulds are in a half-way state ...


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