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If all the world is a metropolis but human population is scarce, it means part of this world is not inhabited by humans. We have seen that, when human presence fades, nature is quick to take over. Just look at Chernobyl and Pripyat. Even the COVID lockdown was sufficient to allow sight like dolphins in Venice or wolves and deers roaming through mountain ...


13

Not QUITE a zero-sum game: Survival of the fittest is not necessarily a zero-sum game. There are several factors that can affect your species, allowing for the species to exist in a variety of states. There is increasing evidence that various species of early hominids existed closer together for longer than archaeologist previously thought, so perhaps ...


11

A few Thoughts: There are a variety of reasons you can see sea serpents who look like this, so here are a few reasons: Sexual display: Most sea serpents don't normally swim this way. In fact, you rarely see them at all. But they were once land animals, and reproduction is highly conserved. So males come out and perform this as a display for females, trying ...


11

Urban Parks In the Indian city of Mumbai there is an urban park/green space that supports a small population of leopards. I believe their chief 'prey' are the local feral dog population. I suppose the same thing could occur with tigers but it would need to be a much, much larger green space to be viable and some larger kind of animal (feral cows/sheep?)would ...


9

Adapt Or Die: To make this work, your tigers need a long period of messiness where they can evolve new traits that allow them to survive in an urban environment. Then, they need to have a new survival strategy that allows them to thrive in an environment filled with quirky, highly intelligent hominids. So you need to figure out how they will need to change ...


7

Not sure how feasable it is with how humans work So, I tried really, really hard to think of a way to make this work. One thing is that a highly confined, "urban jungle" environment could create enough complex three-dimensional space for tigers to be able to hunt. The only problem is this would only work in an environment where the cities are ...


7

Not quite, but... Air - or almost any gas - cannot be pressurized much inside an organic structure, not if you want the structure to be also lightweight - which you do since this is a bird after all. So, compressed air expansion would not do very much. But the attack in itself might work; you just need a different fluid, one that will subtract a lot more ...


6

Just change how they swim. If they swim with vertical undulation instead of lateral, that is exactly the pattern you would expect to see while swimming on the surface. Although the loops would not come completely clear of the water like that but they would be on the surface. snakes often hold the head clear of the water while swimming to improve vision or to ...


6

10.3 Gy is only a little over two U-238 half lives, and not even a full half-life of the main isotope of thorium. That's not nearly enough time to decrease radiation to the point of undetectability. With a frozen core, there will be little in the way of a magnetic field, and what's left after it freezes will decay faster than uranium or thorium. And even if ...


6

Each one may adapt in a different way Let´s start with sponges: They may not have any problem at all. In fact, there are sponges that live happily on freshwater rivers: the family Spongillidae: https://www.nps.gov/articles/freshwater-sponges.htm So these creatures are already adapted. Bivalves: There are many families of them. And (surprise) there are also ...


5

Conjoined octodecuplets There are 18 idential siblings that got entangled in the womb / egg, and have developed into a beast orientated mouth facing outwards. Conjoined tuplets, or "siamese twins" do occur in non humans; although currently they dont quite get up to 18 presently. Starting with a species roughly resembling the desired shape and ...


4

Separate cultures In almost all cases of elves and humans co-existing, with elves having these archetypical long-life traits, elves live separate lives. Wood elves live out in the wild woods, i.e. where there is little in the way of human style civilization. Dark elves live in caves or other areas inhospitable to agricultural human life High elves tend to ...


4

Animals that consume food get two things from it: energy, via chemical reactions with oxygen from air, and materials to build and repair their bodies. The actual process is a lot more complicated, but that's the high-level version. A creature that gets its energy from electricity cannot get matter that way. It still needs to "eat" to get materials ...


4

survival of the fittest It is already mentioned, but not quite to my liking. Survival doesn't mean it needs to be 'better'. It needs to be able to reproduce in a (semi) sustainable way while successfully competing for resources. In our world we can be seen as the apex organism and there's nothing better than us. Yet we're surrounded by other life. Plants ...


4

Tiger King to the Rescue it basically boils down to this: There are More Tigers in Captivity Than in the Wild source Some in zoos, but most in private ownership or roadside attractions, so even if every inch of their habitat on earth vanished tomorrow thousands of tigers would survive. Their numbers in captivity may even increase, as people attempt to "...


4

The 'mouths' could be pockets in between gastralia. The gastralia would be enlarged to form the jaws, with tooth-like scales on the outside. These belly-mouths could be used to grab prey that is too far from the mouth or limbs. This means that such a feature would require a rather long serpentine form


3

Not a serpent. It is improbable that an elongated creature would move like that. There are two standard explanations. 1: Many smaller creatures. https://baleinesendirect.org/en/what-do-we-know-about-harbour-porpoises/ Depicted: porpoises. They move in groups and they can move fast. Seeing a clump of multiple humps (porpoise backs) emerging from the ...


3

The makara could be a crocodilian of some sort If it were more herbivorous, a prehensile nose/lip would help it to eat the plants more easily: This could result in the development of a trunk The mouse ears and pig tusks could be explained as display structures, as they would be nuisances that demonstrate the animal's ability to survive. Similarly, the train ...


3

Its more a question of how the Elves managed to survive than the humans. For example division of labor. For each scientist you need people that sustain them, from food and water production to industrial capacity to build the things they need to creating the luxury products and free time that help the scientists do their job. The Elves might live longer, but ...


3

Frame challenge warning... No forests left - not realistic long-term Plants are ridiculously good at self-seeding, and can make a home in places where it seems improbable that they'd get enough water or nutrients. In all English cities, you will regularly see self-seeded buddleias growing out of the side of the brickwork of railway bridges. In Detroit in ...


3

If I remember correctly, kangaroos use their tail as a third leg to keep their balance, both when hopping and standing. They don't seem to have severe disadvantages when it comes to moving, and being able to have the forelimbs free from the supporting task can be an advantage in certain environments, for example because it allows to grab for food. From a ...


3

The simple answer here is, we don't really know. There is speculation that this is more or less what happened to Homo Floresiensis ("Hobbits" of Flores Island), who had significantly smaller brains than modern humans as well as being under four feet tall -- but so far, we have so little evidence beyond their mere existence, we don't even know if ...


2

It is a sauropod. https://www.sciencealert.com/strange-dinosaur-tracks-in-texas-might-show-giant-sauropods-moving-on-only-two-legs Your long necked, short-tailed creature is a sauropod. It is an airbreather and so it stays at the surface. It walks on the bottom or punts along with legs off the bottom. It is buoyant and for short stretches can swim like ...


2

This creature could have evolved from an early lizard. The reason for the long, flexible neck could be that it is a herbivore: This trait would allow it to eat lots of plants without moving the body. The flexibility of the body would be useful in hiding itself, as it could coil into a ball and hide in a smaller hole. The large size could be useful as an ...


2

As the question already mentioned, delayed maturation and limited propagation rates can be used to offset the competitive advantage provided by extended lifespans. There is an all-too-short class lecture in the movie, Lucy, which contrasts these two survival options and the environments where each of them thrives. Its conclusion, that harsh environments ...


2

Haploid cells There's two types of cells. Haploid and diploid. Depending on your biology grade, you might remember that you have chromosome pairs. Humans have 23 Chomosome pairs, which makes a total of 46 chromosomes. The pairs are important, as each is a sort if backup. If one has a flaw, most often the flaw isn't present as the other can prevent this.This ...


2

It evolved from the pig footed bandicoot https://en.wikipedia.org/wiki/Chaeropus The vernacular description, pig-footed bandicoot, was given by Ogilby in his first description, a name ascribed by Mitchell's party.[2] Europeans settlers reported the species as resembling "small antelopes",[9] a simile that was reported by Bernard Woodward as ...


2

Being gigantic, one of these fierce creatures only weaknesses is the tendency to overheat, particularly in the thermoactive seas it prefers to hunt in. In order to keep cool following a hunt or during long trips, the serpents have evolved to extend alternating portions of their bodies out of the water to promote cooling in the ever present trade winds. Some ...


2

Your tiger need to eat meat other than humans -> unless they learn to use the street protein dispensers, they need prey species that are roughly in a similar size than they eat now (or more caloric). They would starve eating rabbits or rats, and might not be able to fit in the ranging areas of the rodents. => Keep the vegetation in check with sparse ...


2

Osmeterium The osmeterium is a defensive organ found in all papilionid larvae, in all stages.1 The organ is situated in the prothoracic segment and can be everted when the larva feels threatened. The everted organ resembles a fleshy forked tongue (not unlike a snake tongue), and this along with the large eye-like spots on the body might be used to startle ...


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