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Dinosaur evolution

  1. Mar 19, 2003 #1
    Fossil records reveal that dinosaurs thrived on this planet for millions of years, millions of years ago. If they existed for so long why didn't they evolve into much more intelligent creatures? Aren't a few million years long enough to make that evolutionary leap to, say, developing a language, a form of writing, building of towns and cities, development of spiritual concepts...perhaps you see where I am going with this. Is evolution a blanket concept or is it focused on specific species? Doesn't everything in existence "evolve"? I would like to hear some points of view on this, please.
  2. jcsd
  3. Mar 24, 2003 #2
    Yes, every living thing can evolve, but it doesn't have to. Evolution occurs as a result of mutations in the gene, so if a species doesn't mutate too drastically, and isn't hit with any really bizarre/unnatural circumstances, it doesn't necessarily (emaphsis on "necessarily") evolve.
  4. Mar 25, 2003 #3


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    Dinosaurs had many flaws that put them in a bad limb of the evolutionary tree for evolving intelligence.

    Another example of an old animal that hasn't evolved intelligence is the shark - its older than the dinosaurs. It is very good at what it does but is unlikely to develop intelligence.
  5. Mar 25, 2003 #4
    Although dinosaurs were not so stupid as is usually supposed, they did not evolve to a civilization. Why other species evolved (we), that is precisely the question that antropology tries to solve. Of course thee are phyical factors, since a tiny organism will probably survive better bad times than a tank of fourty tons. But why did insects, which are, with no doubt, the organisms best adapted to almost any kind of adverse atmospherical conditions, not evolve to the leading group?

    P.S: the crime statistics' in any big city show that human beings stopped to evolve many centuries ago.
  6. Mar 25, 2003 #5


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    It is indeed a puzzlment. One possible answer is that each species has it's own natural weapons, and we just happen to be the first to specialise in intelligence. Hardly suprising when one considers what an unlikely sort of weapon the brain is, a big, squishy grey organ that remains inside the skull and can never be taken out and used directly.

    The dinosaurs had there own survival tools, and these were very succesful. Larger size, greater speed, stronger muscles or tougher armor all have far more immediate benifits than superior inteligence. So it is possible the dinosaurs never developed inteligence for the same redason the ellectric eel never devloped venom (if you see what I mean).
  7. Mar 25, 2003 #6
    Focussing would meant that somebody is pursuing an aim. There are no objectives in nature. It is just there. So evolution is mainly a series of unbelieveable coincidences that may or may not lead to intelligent life.
  8. Mar 25, 2003 #7

    Another God

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    Everything is Evolving all of the time. Its just that Evolution isn't a directed thing, so you can't really expect much of it. It does what it does. There are certain guidelines which make sure it stays on the straight and narrow : Selective pressures, facts about life, and sexual selective pressures....but essentially, anything which can happen within those guidelines 'can' happen...but probably won't.

    Why didn't Dinosaurs develop Intelligence over the millions of years they were alive? Because it didn't happen is the most simple answer. There is no rule in the laws of evolution that says Intelligence is a good thing. There is no obvious selective pressure pushing towards an increase in intelligence.

    As has already been said: they were good enough at what they did to keep alive, they kept doing it as they were, and they kept staying alive.

    Perhaps species like the Raptors were starting down an evolutionary path towards intelligence. Working as a team to hunt prey implies a level of intelligence. But even so, it still only requires a particualr level, and no more. Once again, there is a pressure pushing for a certain level of intelligence to achieve a desirable goal, and then past that, there is no obvious pressure, so for it to conmtinue evolving down that path is sheer luck (or bad luck as is most often the case)

    The fact is, in terms of this sort of question, the more reasonable thing to be asked (and the question which is more often then not the one which is asked) is not why they didn't..but rather...why did we?

    We are the freaks here. Not them. Intelligence is incredibly stupid in so many ways...It has completely stuffed up evolution in the traditional sense. but thats another story...
  9. Mar 25, 2003 #8


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    Welcome to Physics Forums! Just to add to what has been said...

    Some did become more intelligent. Some of the latter dino species are believed to have been more intelligent than some of the earlier versions. (Not homonid-level intelligence, of course.)

    It is a misunderstanding to equate evolution with progress alone (in particular, progress along the same path we humans took). That is incorrect. Evolution is change, pure and simple. There is no definitive direction toward high intelligence. That happened to be the path our lineage took, but it is not a requirement for evolution. Bacteria have been evolving for billions of years with zero intelligence and in some respects (e.g., population, diversity, longevity), they are the most successful lifeform in evolutionary history. Intelligence has been a key evolutionary feature for homonids, but other traits are key features for other species....like the ability to photosynthesize in green plants, or the ability to retain water in camels, or the ability to swim for fish, etc. (Not that one feature defines a species...evolution occurs on many levels...food gathering, reproduction, immune system, locomotion, etc.)

    All populations of life forms evolve. Gene pools change slightly from generation to generation...for better or worse. Evolution doesn't mean improvement...although natural selection (one aspect of evolution) tends to favor better-adapted forms (for a particular environment) over other competing forms...which is a kind of progress, but then the environment changes which makes some "progress" moot or even a detriment. Similarly, other traits which are not of high significance during current conditions can suddenly become very significant with new environments.

    In short, intelligence is not a destination of evolution, it's a possibility.
  10. Mar 26, 2003 #9
    A bit of an aside, but does anyone know if it is possible from fossil records of dinosaurs to tell whether any were mammalian. I was thinking recently about egg laying mammals we have here like the Echidna and the Platypus and wondering if there was any chance at all that dinosaurs might have also been egg laying mammals. In the large species one would imaging that it would have been much easier to put on weight through suckling, especially for the large herbivores. I'm not sure if it makes sense that you could get enough protein out of leaves and grass to get that big. Anyone think this is possible?????

    Raavin [?]
    Last edited: Mar 26, 2003
  11. Mar 26, 2003 #10


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    Possible, certainly. Especially with the air-breathing aquatic species like the Ictheosaur or the plesiasaurs.

    BTW, a little nit-picky perhaps, but I don't believe the platipus is considered a "mammal". Way I heard it, the Platipus, the Echidna, and the Pangalyn(sp?) make up their own genus (or is it phylum; I never could keep those two strait), called the "Monitremes".
  12. Mar 26, 2003 #11
    You're right about the monotreme bit. They are still mammals though, defined by the fact that they have mammary glands which produce milk. The Echidna and platypus are the only monotremes, I have no idea what a Pangalyn is.

    I'm really making the suggestion that all of the large dinosaurs might have been egg laying mammals. Apparently the bones of the platypus have some reptilian qualities. This could cause some confusion when assessing fossils. If dinosaurs were exothermic, wouldn't it have caused problems for large dinosaurs who lived outdoors if it got cold for too long. How would a T-rex hunt if its body temperature dropped and how would it stand??? How long would it take and at what temperature, for an exothermic animal to lose enough to be unable to move about???

  13. Mar 27, 2003 #12

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    I'm 98% certain that they know what they are talking about. The science/artform behind evaluating fossils and bones etc is very well understood. They have been able to accurately predict many many facts about animals from a single major bone for hundreds of years.

    Anyway, there is more to the Reptilian classification of Dinosaurs than just not having mammary glans etc. Theire skeletal structure is actually what gives it away. Besides, mammals only came into any sort of large numbers towards the end of the reign of the Dinosaurs, so the concept of Dinosaurs being mammals doesn't really make immediate sense. Mammals weren't developed to the stage where they could take on the form of dinosaurs. Reptiles had been around for....well, a long time, and so they had plenty of time to adapt to such large niches.

    Anyway, I shouldn't try to sound so confident. I don't know enough about this really, but I am fairly confident that they know what they are talking about when they make the classifications....
  14. Mar 27, 2003 #13


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    I thought that the current thinking in palientology was that most dinosaurs were endotherms?
  15. Mar 27, 2003 #14
    I had a look around about the endotherm stuff. It would seem that the smithsonian sees the idea of endothermic dinosaurs as not substantiated. Some of the ideas are based around the fact that most (all???) modern reptiles lie flat, unlike dinosaurs, dinos have bird like skeletons and birds are endothermic etc. but they have other reasons why these conclusions are not necessarily valid. Like physics, I think they go for the 'well this explains this so unless we get more evidence or the idea predicts more accurately other observations we are not willing to go there'

    I have no illusions that I know more than them. That would be stupid. The thing about the prehistoric mammals though is an iteresting one. Doing a short search, it would seem that identified carnivorous mammals are all about the size of a domestic cat. I assume though that these are placental mammals. Perhaps these were just the first placental mammals.

    Sharks are interesting. They have different gestation methods from memory. Some just lay eggs, but others lay their eggs internally then they hatch and latch on to the inside wall of the mother and take nutrition from the bloodstream. There are in betweens of these methods too.

    cop this, "The most complex form of shark reproduction, PLACENTAL VlVIPARITY, is employed by the requiem and hammerhead sharks. These advanced families have developed a maternal nutrient system very similar to one found in mammals. After a short period of embryonic dependence on the yolk sac, the empty, flaccid yolk sac interdigitates with the maternal uterine wall to form a yolk sac placenta. The embryo is supported at the end of an umbilical cord which enters its body between the pectoral fins. The placenta transports resources from the mother's bloodstream, including nutrients and oxygen supply, and provides elimination of waste products.

    In some viviparous sharks, such as the sharpnose and some of the hammerheads, additional structures are present. The umbilical cord becomes festooned with "appendicula," leaf-like structures that increase the umbilical cord's surface area for exchange of nutrients, gases, and waste products with the uterine fluid. "Uterine milk," secreted by special cells in the walls of the uterus of these sharks may be absorbed through the extended gill filaments of many species of elasmobranchs, as well as the appendicula and the skin and mouths of the embryos."

    This is a fish. I think that this is a perfect forum to have open discussion on the subject without the constraints of having to worry about little things like facts :wink:.

    from this site http://na.nefsc.noaa.gov/sharks/repro/reprointro.html [Broken]

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