How to Make a Hypothetical Planet and Its Inhabitants.

This instructable is for realistic extraterrestrial design. Star wars/trek have mostly got it wrong- too much like earth. This instructable is for creating things like the daggerwrist or skewer from Wayne Barlowe's Expedition. Remember the number one rule: Don't make things too much like earth

Step 1: Designing the World

This step speaks for itself. Just come up with details that could effect life- heat, geography, climate, gravity, air composition, and so on. Remember that this is what the lifeforms are based on; if you give the planet a low gravity there's going to be a lot of flying things.

Comments

[jakebuck]

while its true that we don't know what other life may look like, there are a few lessons we can learn from our own planet that are applicable in any environment: 1: Every higher animal has a head. Whether its a dinosaur, mammal, reptile, fish, or bird. A centralized area for sense organs close to the brain is a necessity, as it gives you one place on your body you must defend if attacked. That way, you don't have to worry about your nose on your back that you can't reach while the smaller animal feast on it. 2: Outside of the water, 4 main appendages are the minimum for easy movement. If it were any other way, you would see three legged creatures everywhere. In the case of the two legged creature above, a four legged predator would be able to dance around it, while spending less energy on keeping itself erect.

[Mr. Squiggles]

Cephalopods have heads, but the brain's spread out throughout the body. And, with their intelligence levels they would be considered higher animals. Also, while running it wouldn't need to the two legs would be useful because the animal would have two, thick legs as opposed to its four legged predator which runs in a gait that mimics the two legged one of the gyrosprinter. And, would have four, thinner legs which would be more prone to breaking from the force of running.

[jakebuck]

you apparently have no idea of how mechanical systems work. a two-legged creature such as the gyrosprinter would not be able to turn in a fast or efficient manner, and would be prone to falling over, especially in high wind or on unsure footing. As to your statement about four thinner legs being more prone to breakage from the "force of running", when was the last time you broke a leg while running? try this: get spore creature creator (free) and make a creature that resembles the gyrosprinter, you can check out a rudimentary example of how it would move. just look at its stride, the program compensates for balance and turning. when it runs straight, it looks ridiculous, because it is. i am tired of trying to educate you and expand your horizons, and am turning off new post notification so i no longer have to be infected with your ignorance.

[Mr. Squiggles]

I haven't actually broken my legs but there are multiple injuries that do occur from running one example being stress fractures. As for the gyrosprinter the possibility of lack of grip is actually a smaller problem than that of a four-legged animal this is because there-s only two feet to lose footing as opposed to the four possible points of failure. In case of high winds it could lean. I do have to ask if the creature creator extends the back as the gyrosprinter runs

[RGoI]

I just want to point out that if one leg were to slip he would fall flat on his face, if the creature were built like other four legged creatures. Second, try tripping a centipede. If you're corect, it should be 50 times as likely to trip him, if I'm interpriting you're statement right.

[Mr. Squiggles]

 The problem with the centipede argument is that, even though, the centipede has more points of failure they are less important. In the wild a 41 legged centipede should do about as well as a 42 legged one; a three legged elk, on the other hand, won't do as well as a four legged one.

[RGoI]

I believe thats in complete opposition in what youv'e been saying. Also, with the whole 2vs4 leged creatures, with 2 legs being beter, I think we should take a look at humans. We have 4 limbs, 2 for mobilisation and 2 for manipulating objects. HOWEVER, under certain circumstances our arms are used like legs, either because of uneven terain or because of how steep it is. This proves that 4 legs are inherently better than 2 legs. BUT WAIT! Couldn't this be viewed the other way? If anything, this proves that a mixture of legs and arms provides the best mixture. Doesn't it? NO! It proves that however many limbs you have, they're useless if they're not used correctly. This excersise has been to merely ilustrate the point that while bad IDEAS are tolerable if you learn from them, bad REASONING should be corrected as soon as possible.

[Mr. Squiggles]

What an astute observation: "Limbs are useless if used wrong", It could be applied to many other subjects, such as computer repair: "Your computer isn't working because your using it wrong." And also, you misunderstood my argument. I'm not saying that any amount of legs is better than any other amount (although if there were an animal with thousands it would be a bit ridiculous) I was arguing that it could be advantageous for one specific animal to become bipedal--and also not in side-by-side configuration you were talking about. I will now add that your initial "exercise" was rather poorly thought out, as arms are only useful if they can manipulate things. It's not like an impala would become bipedal and have so many more options. It would still be an impala with an impala brain and impala hooves. If it had the hands and brain to make a tool or climb it would help, bot if not, it would just be a slower, more easily seen impala.

[jtobako]

4 legs are an adaption from the way fish swim-the body moves side-to-side, a motion that is continued with reptiles like crocodiles. The proto-mammals developed an up-and-down running style, which created the motion of whales and seals. On land, a seal moves with 3 limbs.

[jakebuck]

A seal does have 4 limbs, the legs are stunted, and they are considered marine mammals. Besides, Bears tear the crap out of them on land, just reinforcing my statement

[Mr. Squiggles]

As you've stated they're marine mammals. Fish don't move that fast on land either.

[jtobako]

Seals move on land with a 3 legged gait and Phorusrhacos tore the crap out of it's 4 legged prey. What's your point?

[Mr. Squiggles]

They technically use four limbs, but the back two are used as one.

[jtobako]

Snakes? Kiwi? T-rex?

[Mr. Squiggles]

(removed by author or community request)

[Grey_Wolfe]

One might also mention that the T-rex is not a highly effective form for predation. It's small arms are of little use in combat, which is necessary when one must kill its prey. Cranial structure suggests a scavenger, not predator. It's tiny arms aren't such a disadvantage when it's 'prey' is already dead. Also, T-rex is extinct, and unless we are to assume it died off due to an as yet unidentified cataclysm, then we might assume that nature decided it was not to useful in it's raptoran form.

[Dilong_paradoxus]

Actually, Tyrannosaurus was one of the most deadly predators earth has ever seen, even though it's waaaaay too overpopularized. Tyrannosaurus had binocular vision, useful for hunting but not for scavenging. Its legs also permit it to run at quite high speeds, so it would have been able to catch almost every type of animal it lived with. Tiny arms aren't really a disadvantage, especially when you have a head full of bone-crushing teeth. If Tyrannosaurus wasn't well adapted to its environment, then it wouldn't have evolved in the first place. Evolution would have tended to steer the Dinosaurs in a different, more well adapted direction. Sorry for ranting, but I can't help it.

[bighead5454]

no it wasnt it was a scavenger and could barely see anything that dosent move

[Dilong_paradoxus]

The barely seeing anything that didn't move was more of a plot device introduced in jurassic park as a side effect of the frog DNA used to reconstruct the Tyrannosaurus genome. Neither birds nor crocodiles (the closest living relatives) have this problem, so by phylogenetic bracketing we can assume Tyrannosaurus didn't have this, either.

And for the scavenger part, it would help if you could actually present some evidence for why it was a scavenger. If you note my previous post, it presents multiple lines of evidence supporting my beliefs, as does the post it is arguing against.

[jtspgs]

From what I understand, spinosauras-agyptus or more commonly known as the Spinosaur would actually hunt T-Rex, so wouldn't the spinosaur be the most deadly predator?

[Mr. Squiggles]

Scientists actually theorize that the spinosaur was a fish eater/scavenger, essentially a giant osprey or grizzly bear.

[Dilong_paradoxus]

Spinosaurus and Tyrannosaurus lived at opposite ends of the Cretaceous, and completely different parts of the world. They didn't even meet!

Spinosaurus, even though depicted killing a Tyrannosaurus in Jurassic park, could never do that even if the two did meet. Tyrannosaurus had jaws that could exert the force of a medium-size car, easily enough to crush bone. Spinosaurus had bigger teeth, but a relatively weak jaw. It probably ate fish and carrion, while Tyrannosaurus specialized in big animals.

So no, Spinosaurus aegypticus was not the deadliest predator ever to live.

[Mr. Squiggles]

I still think that the T-rex was more like a short faced bear- a scavenger which just looks intimidating.

[Dilong_paradoxus]

But why the long legs (perfect for catching prey) and binocular vision? neither would be very useful for scavenging.

[Mr. Squiggles]

To simply look imposing

[Dilong_paradoxus]

What would be the point? If you weigh six tons I don't think anything's going to want to bother you, possibly excepting other Tyrannosaurs.

[Mr. Squiggles]

Which is exactly the point you scare other scavengers away from the carrion.

[Dilong_paradoxus]

Why do you need all the other stuff then? If you're six tons and have jaws that can crush a car, why would you need legs built for speed or binocular vision? You don't.

[Mr. Squiggles]

You just need to look like you're a super predator. It works like this: agile, small predators kill their food, large, menacing T-Rex scares the predators away and eats the food.

[Dilong_paradoxus]

Right, but you don't need to be fast or have depth perception to do that. Tyrannosaurs get faster and better at seeing forward the closer they get to the end of the Cretaceous, whereas evolution would cause those traits to be selected against if they were pure scavengers.

[Mr. Squiggles]

They evolved to look more like predators, anyway why would evolution go against binocular vision, seeing as It helps only among prey species, which the T-rex isn't.

[Dilong_paradoxus]

You don't have to have long legs to look like a predator. Binocular vision actually only evolves in predator species, because it gives depth perception. Non-binocular vision gives a wider field of view, but the animal cannot judge distance accurately. That's good for prey animals and scavengers, but not predators.

[Mr. Squiggles]

There are herbivorous primates and primates that only prey on grubs that don't require binocular vision, yet primates have it. Binocular vision doesn't; however, manifest itself in species that are lower on the food chain which need to see where the predators are coming from.

[jtobako]

About half the life span of a Tyranosaur is spent at a size of the predators you are claiming that they don't have to protect themselves against.

[Mr. Squiggles]

However, since there's evidence they live in packs the adult T-rex' could look after the smaller, juvenile ones.

[Dilong_paradoxus]

Primates are a special case, as they live in trees. And that's exactly what I just said. Tyrannosaurus was not by any measure "lower on the food chain," and it was probably the top predator in its ecosystem.

[RGoI]

Actually, he makes a good point with the trees. If you swing from vines all day, a mistep could be lethal. So, nature would select those that could tell distance better.

[Mr. Squiggles]

But not being low on the food chain doesn't mean being a predator, it just means that it isn't prey, something that can be achieved through being large.

[Dilong_paradoxus]

Very good point.

[jtobako]

"They evolved to look more like predators..." You mean they didn't start out as predators? Which line DO they belong in then? Binocular vision is present in ALL species-rabbits, for example, are a classic prey species and have 5-10 degrees of binocular vision out of something close to 300 degrees, where owls have 70 out of 110 degrees or so. And cat's noses get in the way of their vision as well, the common stripe along the nose is supposed to help them 'aim'. Are you now claiming that they can't be predators now? Before you start in on size range of predator and prey, the local feral cats are bringing down rabbits their own weight.