If we ever meet aliens from another planet will we be surprised by what we see?

[Cainkane1]

I remember reading long ago that if we ever do meet an intelligent being from another planet we will be reminded of something here on earth.

What are your thoughts on this?

[MG1962]

How long is a piece of string

[Craig B]

Originally Posted by Cainkane1

I remember reading long ago that if we ever do meet an intelligent being from another planet we will be reminded of something here on earth.

What are your thoughts on this?

If the beings are intelligent, we will be reminded of ourselves.

[rjh01]

What will happen if or when we meet aliens from another planet is unknown. However we can look at what happens when we meet hunter-gatherers.

[Madalch]

Originally Posted by MG1962

How long is a piece of string

I thought How Long was one of the great generals of Imperial China.

[Puppycow]

Maybe we'll be surprised by how similar they are. Who knows.

[Farsight]

My thoughts on this are parallel evolution.

For example, sabre-toothed cats have evolved repeatedly during Earth's history. And the Ichthyosaurs resembled dolphins. The "shape" of an animal does appear to relate to its ecological niche and what it does for a living. So if there was some other planet where there was an ocean, I'd expect to see fish. And chasing those fish, I'd expect to see dolphins.

I thought the movie Avatar was interesting in this respect. You can work out that all the creatures were descended from six-legged things with multiple eyes, much like our insects. But then efficiency kicks in: you only really need two eyes for binocular vision, so the other eyes get small as per the Ikran. And you only really need four limbs for locomotion so your forelimbs start to fuse as per the lemurs, then fuse all the way as per the Na'vi. Only you need free hands to manipulate, which then drives brain evolution along with having to call to communicate. I reckon they got it more or less right. Of course, the Na'vi were more humanoid than they might have been to allow the audience to identify with them, but that's artistic licence. If they'd had Thanator fangs and quills and claws and those lip-flaps, it wouldn't have been the same.

But hey, if something like totally alien turns up on the White House lawn, I wouldn't be totally surprised either. Because we do have squid.

[RecoveringYuppy]

Originally Posted by Farsight

The "shape" of an animal does appear to relate to its ecological niche and what it does for a living. So if there was some other planet where there was an ocean, I'd expect to see fish. And chasing those fish, I'd expect to see dolphins.

But why expect animals at all? Animals were a late development here on Earth, dependent on a lot of things that happened before. At the moment I don't think we can even count on alien life being based on cells, never mind all the later development of life.

[MG1962]

Originally Posted by Madalch

I thought How Long was one of the great generals of Imperial China.

No that was his brother Hung Low

[Gord_in_Toronto]

Originally Posted by Puppycow

Maybe we'll be surprised by how similar they are. Who knows.

Dr Who?

I suppose he does (know).

[Dinwar]

Quote:

For example, sabre-toothed cats have evolved repeatedly during Earth's history. And the Ichthyosaurs resembled dolphins. The "shape" of an animal does appear to relate to its ecological niche and what it does for a living. So if there was some other planet where there was an ocean, I'd expect to see fish. And chasing those fish, I'd expect to see dolphins.

The problem is, parallel evolution (more commonly called convergent evolution) is typically the result of different organisms adapting to the same niche with the same physical constraints. And even that's not a guarantee that they'll look alike: Icthyosaurs resemble dolphins--but mosasaurs don't resemble xanthid decapods.

I see no reason to assume that intelligence will necessitate physical similarities. Perhaps a brain of a certain size is necessary, but after that, anything goes as far as I can tell. And "brain" is a loose term here--a neural net would work just as well as a central brain.

Cephalization is an advantage to some animals, but not to all--at least one line literally lost their heads. And there's no reason to assume that evolution will keep the head where we're used to it. Or in the configuration we're used to. And if something as basic as "Where's the head?" is an open question, the rest is wide open.

Quote:

I thought the movie Avatar was interesting in this respect. You can work out that all the creatures were descended from six-legged things with multiple eyes, much like our insects. But then efficiency kicks in: you only really need two eyes for binocular vision, so the other eyes get small as per the Ikran. And you only really need four limbs for locomotion so your forelimbs start to fuse as per the lemurs, then fuse all the way as per the Na'vi. Only you need free hands to manipulate, which then drives brain evolution along with having to call to communicate. I reckon they got it more or less right. Of course, the Na'vi were more humanoid than they might have been to allow the audience to identify with them, but that's artistic licence. If they'd had Thanator fangs and quills and claws and those lip-flaps, it wouldn't have been the same.

Check out the debate about why we have five fingers sometime--your post sounds a lot like it. The debate was answered when we found the first terrestrial vertebrates--and realized that they had a pretty random number of digits (as in, the same critter could have different numbers of digits on different limbs). The reason we have five fingers? Pure, random chance. And chance is going to dictate more of evolution than many people realize. For example, if all the human-like critters on the alien world are right in Ground Zero for a K/Pg size impact, they're not going to evolve; and as far as evolution is concerned, impacts are random (unless you're in the Heavy Bombardment phase of planetary development impacts don't happen often enough to influence evolution to any great extent).

[Sherman Bay]

Originally Posted by Farsight

But hey, if something like totally alien turns up on the White House lawn, I wouldn't be totally surprised either.

Better check the last election results to be sure.

[Craig B]

Originally Posted by Dinwar

(unless you're in the Heavy Bombardment phase of planetary development impacts don't happen often enough to influence evolution to any great extent).

Is that true? I'm no palaeontologist, but it has been my understanding for a long time that the K/T Boundary event had a most profound effect on subsequent evolution, so that without it mammals would never have diversified as they did following the mass extinctions, and we would therefore never have evolved.

[Skeptic Ginger]

Originally Posted by Dinwar

The problem is, parallel evolution (more commonly called convergent evolution) is typically the result of different organisms adapting to the same niche with the same physical constraints. And even that's not a guarantee that they'll look alike: Icthyosaurs resemble dolphins--but mosasaurs don't resemble xanthid decapods.

I see no reason to assume that intelligence will necessitate physical similarities. Perhaps a brain of a certain size is necessary, but after that, anything goes as far as I can tell. And "brain" is a loose term here--a neural net would work just as well as a central brain.

Cephalization is an advantage to some animals, but not to all--at least one line literally lost their heads. And there's no reason to assume that evolution will keep the head where we're used to it. Or in the configuration we're used to. And if something as basic as "Where's the head?" is an open question, the rest is wide open.

Check out the debate about why we have five fingers sometime--your post sounds a lot like it. The debate was answered when we found the first terrestrial vertebrates--and realized that they had a pretty random number of digits (as in, the same critter could have different numbers of digits on different limbs). The reason we have five fingers? Pure, random chance. And chance is going to dictate more of evolution than many people realize. For example, if all the human-like critters on the alien world are right in Ground Zero for a K/Pg size impact, they're not going to evolve; and as far as evolution is concerned, impacts are random (unless you're in the Heavy Bombardment phase of planetary development impacts don't happen often enough to influence evolution to any great extent).

OK, while one species might have evolved less cephalically, how do species lines evolve in general? Clearly primate brains have been unidirectionally evolving when it comes to brains.

What about birds. Are crows later on the evolutionary branch than chickens? Or does something else besides later on the tree select more and less intelligence? I can see predators and social needs affecting intelligence but I'm having a hard time picturing what would naturally select less intelligence as a rule.

[Halfcentaur]

Originally Posted by Farsight

My thoughts on this are parallel evolution.

For example, sabre-toothed cats have evolved repeatedly during Earth's history. And the Ichthyosaurs resembled dolphins. The "shape" of an animal does appear to relate to its ecological niche and what it does for a living. So if there was some other planet where there was an ocean, I'd expect to see fish. And chasing those fish, I'd expect to see dolphins.

I thought the movie Avatar was interesting in this respect. You can work out that all the creatures were descended from six-legged things with multiple eyes, much like our insects. But then efficiency kicks in: you only really need two eyes for binocular vision, so the other eyes get small as per the Ikran. And you only really need four limbs for locomotion so your forelimbs start to fuse as per the lemurs, then fuse all the way as per the Na'vi. Only you need free hands to manipulate, which then drives brain evolution along with having to call to communicate. I reckon they got it more or less right. Of course, the Na'vi were more humanoid than they might have been to allow the audience to identify with them, but that's artistic licence. If they'd had Thanator fangs and quills and claws and those lip-flaps, it wouldn't have been the same.

But hey, if something like totally alien turns up on the White House lawn, I wouldn't be totally surprised either. Because we do have squid.

In the background science for Avatar, Pandora's gravity is lesser than Earth's and the atmosphere is considerably denser. The reason for the extra legs is thought by the fictional scientists to be an evolutionary advantage for traction.

According to the background encyclopedia, a Terran who has just arrived at Pandora would feel like they were walking into a strong breeze sort of.

They discuss why the Na'vi came from 6 limbed primate like animals, but do not know why they lost the extra limbs, though the fused limbs are noted in some species,...it's left at being speculated.

Of course, aesthetic design wise, we know it was for making them appealing and more identifiable, but I think it's neat how much background Cameron put into the science of this world in the decade he was working on the subject.
I look forward myself to seeing more movies which will not be hindered by the archtypical Romeo and Juliet story which seems to fuel so much criticism.

[Ladewig]

Well, one does want ones optical sensors near the top ; the ears should not be too close together.

I guess it might have some sort of antennas or feelers. Maybe some senses we don't have.

All I can say is the fundie Christians will be surprised.

[rjh01]

Aliens could be reptiles. If they are mammals females may not have large breasts. They should have two arms and two legs, which may be shorter or longer than ours. Their feet too could be a different size. The number of fingers may also be different.

[Roboramma]

Originally Posted by rjh01

Aliens could be reptiles.

I highly doubt that there are any alien reptiles.

I find it relatively plausible that somewhere there is alien life that is similar to animal life: that it uses the energy captured by photosynthetic lifeforms to live and reproduce, that it thus needs a digestive system, and some means of locomotion (in order to facilitate that collection), and that competition has spurred an arms race in that locomotive facility, so it's quite advanced.

It's possible that some of these alien "animals" are similar to reptiles in some respects, but they wouldn't be reptiles, and I'd bet quite a bit that a competent scientist could tell the difference.

[Multivac]

There is no reason to think that they would resemble us in any way, but I'm sure they would have some questions for us. For example: "let me get this straight. One of your countries sent men to your natural satellite, to get there before another country, and you haven't been back for 40 years? What kind of retards are you?"

And "Do you still think digital watches are a pretty neat idea?"

[rjh01]

Originally Posted by Roboramma

I highly doubt that there are any alien reptiles.

I find it relatively plausible that somewhere there is alien life that is similar to animal life: that it uses the energy captured by photosynthetic lifeforms to live and reproduce, that it thus needs a digestive system, and some means of locomotion (in order to facilitate that collection), and that competition has spurred an arms race in that locomotive facility, so it's quite advanced.

It's possible that some of these alien "animals" are similar to reptiles in some respects, but they wouldn't be reptiles, and I'd bet quite a bit that a competent scientist could tell the difference.

OK, let me re-phrase what I said. Maybe they lay eggs rather than give birth to live babies. Maybe the mothers do not produce milk. They may not have any hair.

[Akhenaten]

Originally Posted by rjh01

OK, let me re-phrase what I said. Maybe they lay eggs rather than give birth to live babies. Maybe the mothers do not produce milk. They may not have any hair.

That's not rephrrasing it at all - it's saying someting completely different.

Equally silly though, I suppose.

[Wolrab]

I don't have a clue as to what an intelligent alien race would look like, but if it had two sexes, Kirk would hit it and if they didn't, Riker would try.

Since we only know of one (DNA based Earth life) version of carbon based life developing on a terrestrial planet, we can only imagine and I'm not sure how good our imagination is.

[Farsight]

Originally Posted by Dinwar

The problem is, parallel evolution (more commonly called convergent evolution) is typically the result of different organisms adapting to the same niche with the same physical constraints. And even that's not a guarantee that they'll look alike: Icthyosaurs resemble dolphins--but mosasaurs don't resemble xanthid decapods...

All points noted Dinwar, sure, it's no guarantee, and yes, we can't assume anything. That's what I was trying to get across with my White House lawn quip. I certainly don't subscribe to the Star Trek notion of intelligent aliens, where they're all essentially human with little distinguishing features like pointy ears or a cornish-pasty head.

[Correa Neto]

Meeting an alien by itself would be a highly surprising event...

This put, humanoid aliens would surprise me, but if they were huge brains surrounded by squid-like tentacles, I would also be surprised.

[Dinwar]

Quote:

OK, while one species might have evolved less cephalically, how do species lines evolve in general? Clearly primate brains have been unidirectionally evolving when it comes to brains.

That's just it--there isn't any "in general". There's what each individual lineage does, but a big chunk of that is often due to random chance.

Horse evolution is an iconic example of this type of thing. If you start with a modern horse and follow the line back through time you get the impression that earlier horses always were smaller and had fewer hooves. It's a pretty strong trend. And a lot of people have stated exactly that--horse evolution is, according to some views, a quesiton of increasing body size and decreasing numbers of toes. However, if you start from the earliest horses and work your way forward through time, an entirely different story emerges. Horse body size is incredibly variable, ranging from smaller than poneys to larger then the guys pulling the Budweiser wagon, all living at the same time. Some horses lost toes, but other lines GAINED toes--one even had claws (the evil horse-like things from the Belgariad actually existed once). There's no "story of horse evolution"; there's dozens, all being written at the same time. The reason we can pretend there's "the story" is because most horses died out at the end of the Pleistocene, witih only a handful of lineages surviving.

Humans are the same way. When you look at the types of human species we've found, starting from the earliest and working your way forward, it becomes obvious that we were not inevitable--in fact, we almost didn't make it.

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I can see predators and social needs affecting intelligence but I'm having a hard time picturing what would naturally select less intelligence as a rule.

Lots of things. Greater intelligence often comes at a metabolic cost. Our brains weigh something like a few pounds, yet contitute either 20% or 40% (I forget which) of our metabolism. If greater intelligence didn't help you find a mate, it wouldn't be worth it in areas where food was scarce. Or, it could be that one sex prefers stupid mates, for whatever reason. Sexual selection can do incredibly weird things to a species. Or it could be random chance. Evolution is an emergent property of population genetics, and since no species is ever at Hardy/Weinburg Equilibrium random genetic drift always plays a roll. There are numerous ways that something like intelligence can be selected against. Remember, evolution doesn't make organisms better--it just makes them good enough to survive their local environment, for now.

And it's interersting to note that all of your examples or chordates. You haven't included any arthropods in your assessment, despite arthropods being the dominant animal group on Earth (in terms of numbers, gross tonnage, etc). Molluscs could easily evolve intelligence--octopi can outsmart humans already, for example. Bryozoans are forming an entirely novel mode of life right now; it's entirely plausible at this point to assume that alien life will be a collonial organism, with each "animal" being the equivalent to our cells (bryozoans have collonies that are mobile and in which the members are specialized in ways very much like cellular specialization in multicellular life--including specialized polyps for movement and reproduction).

And all of THAT assumes that life in the Phanerozoic is life as such. Which is false. The Ediacaran Period included a number of animals that are so weird we still don't know what they are. We don't know how they reproduced, we're not sure how they ATE, and for many of them we're not all that certain how they lived. It's entirely plausible that life on an alien world would consist of leathery sacks of tissue absorbing nutrients from algal matts on the sea bed.

Originally Posted by Roboramma

I find it relatively plausible that somewhere there is alien life that is similar to animal life: that it uses the energy captured by photosynthetic lifeforms to live and reproduce, that it thus needs a digestive system, and some means of locomotion (in order to facilitate that collection), and that competition has spurred an arms race in that locomotive facility, so it's quite advanced.

This, I'll more or less agree with. Photo- or chemosynthetic organisms are required for life to exist, so yeah, we'll see those. Eating those organisms is an obvious evolutionary step, and relatively easy to make at the level of plankton, so we'll probably see animals. I'm not sure whether the animals will be the ones to move; a huge number of animals on Earth don't. And I'm not sure there will be the hard line separating plants and animals that we see on Earth--I think that our dichotomy is the result of chance, rather than biological necessity. And it's not really that hard of a line, come to think of it--a number of plants eat animals, and we ourselves utilize solar radiation to generate nutrients.

Quote:

It's possible that some of these alien "animals" are similar to reptiles in some respects, but they wouldn't be reptiles, and I'd bet quite a bit that a competent scientist could tell the difference.

Gimme one of their skulls and I'll tell you in a few seconds. It's actually not as flippant a remark as you probably think--I constantly gripe that mammology is all skulls and teeth, which is hell for a field like mine where we find isolated longbones (ribs, radii, femurs, etc).

[GlennB]

I suppose it would depend somewhat on whether we visited them or vice-versa. Being 'intelligent' and being able to build complex structures or machines aren't synonymous. Perhaps they live in water and yet could out-philosophise puny human brains with one tentacle tied behind their backs?

[Soapy Sam]

If we meet one, then either we went to meet it, or it came to meet us.
Given our current technology, we must suppose the latter.

If it got here across interstellar distances then, either it has FTL tech or a very long lifespan and some way of staying sane for very long periods of boredom.

It must also be able to protect itself and it's reproductive capacity from the hazards of outer space- and it must be able to acquire energy and matter from the interstellar medium.

In short, it's a machine.

It may well be a matt black cuboidal monolith.

[theprestige]

I think we'll be surprised and not-surprised, in equal measure.

A lot of things about the aliens will probably make little or no sense at first. Once we learn more about their origin and evolution, things that previously didn't make sense will make more sense. A giraffe's neck doesn't make a lot of sense, until you see its habitat and diet. Then it's not very surprising at all.

But there will also be some things that are very surprising, even when we know the aliens' background. Novel evolutionary solutions, maybe, or adaptations to environments we hadn't considered. Or even--perhaps especially--conscious cultural and biological choices that diverge substantially from our own paradigms.

[Dinwar]

Originally Posted by Soapy Sam

In short, it's a machine.

Not necessarily. A collonial organism with a hard, mineralized skeleton could concievably withstand the dangers of space--radiation, for example, wouldn't be as much of a concern.

And boredom is only a human problem. I'd say it's likely only a MODERN human problem. People sailing on wooden ships weren't concerned about boredom, despite being on those ships for months at a time. But even if we assume that they take many years to reach us, there's no proof that they'll be bored. When was the last time you saw a bord lobster? Or a bored sheep? I get that those aren't the smartest critters in the world, but my point is that boredom isn't a universal trait on our planet, so we cannot assume that it will be present on another planet.

[GlennB]

Originally Posted by Dinwar

And boredom is only a human problem. I'd say it's likely only a MODERN human problem. People sailing on wooden ships weren't concerned about boredom, despite being on those ships for months at a time. But even if we assume that they take many years to reach us, there's no proof that they'll be bored. When was the last time you saw a bored lobster?

Not so many years ago I worked in the residential care and education of Asperger's teenagers. One of them said that if we ever needed people to man a 10-year space flight then pick high-achieving Aspies and give them a bunch of their favourite video games.

I mean this with no disrespect to the kids I worked with. But 'boredom' is different strokes for different folks.

[Skeptic Ginger]

Originally Posted by rjh01

OK, let me re-phrase what I said. Maybe they lay eggs rather than give birth to live babies. Maybe the mothers do not produce milk. They may not have any hair.

Wouldn't that be weird, humanoid creatures that lay eggs?

[ben m]

I for one volunteer to be surprised by anything whatsoever. Humanoid? Surprised. Amoeboid, with an endoskeleton? Surprised. Exoskeleton? Also surprised. Floating blue-ish energy ball? Still surprised. Etc.

[Correa Neto]

I don't think being humanoid and egg-layig are incompatible.

Egg-laying would remove a factor that limits the size of our brains: female's hip bones. Egg-laying could account for a small gray-type (real) alien, with a huge head and small narrow body.

If dinosaurs or birds (or birdosaurs, if you preffer) evolved to a sentient species, quite possiblly it would be an egg-laying species. Heck, why restrict it to reptiles and birds? Maybe in some alternate Earth, the sentient platypus rule...

[Skeptic Ginger]

When you look at the history of evolution on Earth, it seems to me there are some general principles that might apply. Take the Cambrian Explosion, for example. You have a lifeless planet, then you get life forms, and there is a vast amount of environment that is essentially unclaimed. Once multi-celled organism take off, you get a massive explosion of life forms, many many mutations are successful because there is no competition.

Then the sorting begins. Competition and the environment seem to lead to the same outcomes even if the organisms get there through different means.

There are only a few kinds of locomotion, for example. And it would seem that hopping, 4 legs and 2 legs won the large life-form, land locomotion contest. Insect forms seem to have had a size limitation as do birds.

Plants, OTOH, don't need locomotion. But we have no evidence that without locomotion intelligence as in conscious thought evolves. In all the plants in all the world not one evolved a central nervous system.

There are 2 kinds of eyes. Perhaps a third kind could have evolved and the 2 that did are coincidental but it could also be that the purpose both eyes serve their owners limits the successful options. One thing that is certain is creatures need some means of detecting their environment.

There might be logical reasons 'large' as in dinosaurs only last until life fills up a certain proportion of the surface. The dinosaurs were dying out before the Chicxulub event.

While maybe these hypotheses will be impossible to test until we find ET life, I do think there are reasonable principles we can deduce from the 3.5 billion+ year history of life on Earth.

[Skeptic Ginger]

Originally Posted by Correa Neto

I don't think being humanoid and egg-layig are incompatible.

I didn't mean my question that way. I meant, wow, that's weird to think about.

Originally Posted by Correa Neto

Egg-laying would remove a factor that limits the size of our brains: female's hip bones. Egg-laying could account for a small gray-type (real) alien, with a huge head and small narrow body.

Couldn't just having a shorter gestation, being born earlier or just having brains grow more in infancy also result in bigger brains?

Now that you mention it, however, I'm guessing the maternal heart and lungs provides certain things a yolk cannot. Maybe a large brain really needs more oxygen while growing?

[quarky]

I would expect to be very surprised, which isn't surprising, and in fact, would reduce some of the surprise, but:

Its getting hard to find a niche on Earth that isn't exploited by some sort of organism.
The extremophiles seem to work the niche of no competition.
Then there's the deep sea vent beasties, working a whole new angle, as well as near endless species adapted to total darkness; steady temps; mind-crushing pressures, etc.

Conglomerate organisms and superorganisms (as in ant colonies) give some credence to ultra-bizarre possibilities.
adding to that, we know have gene splicing and new organisms that are brought about through other organisms efforts.
Even something as mundane as horses...people now breed miniature horses. Look at all we've done with dogs. And of course, artificial intelligence is a hot topic, with many assuming its inevitability.
As someone pointed out (sorry, i forget who) a neural network might suffice as a large brain, requiring no particular head, much less 2 eyes and other various anthropomorphic tendencies.

I wouldn't be surprised to be very surprised. In fact, it might be that we simply wouldn't notice or register that we were in contact with a new life form of grand intelligence.

Look at how long its taken us to open up to all the new species we uncover, almost daily.
look at the surprises that octopuses and ravens have provided, long after we thought we knew all about them.

Opposable thumbs is likely to have very little value in alien niches.
Whereas, selection for exotic radiation tolerance; fantastic pressure; boiling sulfuric acid, and so forth...that might be where its at. after all, there are animals that live in boiling hot springs and extremely salty lakes.

It would be surprising to me if there wasn't all manner of life "out there".

Bigfoot, maybe not so much.

[dasmiller]

Originally Posted by Skeptic Ginger

What about birds. Are crows later on the evolutionary branch than chickens? Or does something else besides later on the tree select more and less intelligence?

I'm not sure what you mean by "later," but bear in mind that contemporary crows, chickens, cows, grasshoppers, amoebae, etc, have exactly the same amount of evolutionary time behind them.

ETA: my eukaryotic bias is showing. Of course, the evolutionary time applies for our contemporary prokaryotic and archaeon friends.

My bias is slightly ironic since the vast majority of cells in my body are not, in fact, eukaryotic.

[GlennB]

Originally Posted by quarky

Opposable thumbs is likely to have very little value in alien niches.

In terms of their survival, very possibly.

In terms of our species meeting in an interplanetary bar-diner then I'd say that this whole 'thumb' business might, very conceivably, be a serious issue.

Damn it. I've spent a lot of the day working a crowbar, pincers, centre-punches, hammers and rotary sanders while trying to visualise how a land-octopus might work these tools ....

[Dinwar]

Originally Posted by Skeptic Ginger

There are only a few kinds of locomotion, for example. And it would seem that hopping, 4 legs and 2 legs won the large life-form, land locomotion contest.

This is an example of historic contingency. The reason we have four limbs is because the lobe-finned fish we evolved from had four limbs. If it'd had six, or eight, or three, we'd have six, or eight, or three. And it was entirely possible for us to do so--all it would have taken was a different fish coming onto land.

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There might be logical reasons 'large' as in dinosaurs only last until life fills up a certain proportion of the surface. The dinosaurs were dying out before the Chicxulub event.

I've seen a number of studies refuting this. First and foremonst, dinosaurs didn't go extinct--they're still with us. Secondly, in my opinion the apparent demise of dinosaurs prior to the K/Pg impact event is due to the Signore-Lipps Effect. Studies where extremely detailed sampling have been done up to the K/Pg boundary have shown dinosaurs to be alive and well up to that boundary. Diversity and ecology are always a pain to assess, though.

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Plants, OTOH, don't need locomotion.

I wonder....Plants DO move, both to follow the sun and in response to other stimuli. And venus fly traps are proof that "plant" doesn't equal "autotroph", necessarily. It would be interesting to see what happens to a venus fly trap over a few million years. It's not unreasonable to speculate that they'd develop locomotion, even crude hunting behaviors. If a planet had something like insects (even frogs, which scares the CRAP out of me--PLANTS are eating CHORDATES on our planet, right now!), and something like venus fly traps, I could see those fly traps evolving into primative insectovores not unlike our own shrews and voles (only a completely different bauplan and physiology).

Mammals started out more or less eating bugs in the Triassic. Look how far we've come. Imagine what an insectivorous and mobile plant could do!

[quarky]

Originally Posted by GlennB

In terms of their survival, very possibly.

In terms of our species meeting in an interplanetary bar-diner then I'd say that this whole 'thumb' business might, very conceivably, be a serious issue.

Damn it. I've spent a lot of the day working a crowbar, pincers, centre-punches, hammers and rotary sanders while trying to visualise how a land-octopus might work these tools ....

We've barely begun to manipulate our own species, which could add to the strange potential. My favorite futuristic human is the Siamese octuplet, with the single central brain, and 32 appendages, in a radial symmetry configuration.
It would work the niche of shallow tropical beaches, eating shellfish and rolling along, partially submerged. If alien intelligent beings had a 1000 year head start on this, with less ethical squeemishness, well, the possibilities are extraordinary.