What would today's world be like if dinosaurs had somehow survived? To give you a better grasp, if human society had grown up among dinosaurs what might be the effects on our scientific and religious customs as well as our technological development assuming all known major dinosaur species still somehow walked the earth?
closed as too broad by Aify, L.Dutch♦, Hohmannfan, Mołot, Vincent Mar 25 '17 at 18:35
Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.
If dinosaurs were still around today, I suspect they would look far different than what our current image of them is. The atmosphere has changed heavily and it's no longer possible to get quite the level of giantism that more classical forms of dinosaurs eventually reached. I suspect they'd be considerably smaller, and probably much more agile.
Other note here is that the dinosaurs wouldn't have had to overcome a single extinction event...that would have had to overcome several and each one of these events would shape their evolution. The Pleistocene era had several ice age related extinctions that saw several large mammalian species go extinct (repeat occurences, most recent may have only been 10k years ago). There are also several volcanic events such as the toba catastrophe 70k years ago that almost finished off humanity and brought the Earth into a 1000 year cooling period. There is very little chance of a large dinosaur surviving this event. 640k years ago, the yellowstone super volcano would have impacted them as well
This likely means the classical dino that we know would never have made it to current day even if the asteroid impact that claimed them never occured. Most likely we would see a similiar trend with dino's as we saw with mammals as smaller more versatile creatures become more dominant as the large ones die off. This is probably a good time to point out birds are exactly this...an evolution of the dinosaurai clade.
Humans are quite likely responsible for a few extinctions early in our history...the Cave bear and the sort found themselves in direct competition for caves and other natural shelters, and we won that battle. Any large dinosaur that saw itself in competition with humans would have died off pretty early in our human history.
With all that said..."scientific and religious customs as well as our technological development" is the question, and I think the answer is no more than the wooly mammoth did. The old tribes that depended on them would have them at the core of our beleifs, but as they died off we'd forget them to history.
Theropods are still with us. You just don't recognise them as being related to T-Rex because we grew up with reconstructions that look like lizards and walk like godzilla. A T-Rex hatchling actually looks like a chicken. Had the similarity been known up front, you'd say that the world was filled with huge scary birds.
The period of gigantism resulted from the needs of herbavoirs grazing on low-quality food, predators growing to match, and a resulting arms race. They were over-specialized and the iconic dinosaurs were in decline due to habitat change, and obsolecence due to the continued evolution of plants. Today we have cows that graze on grass because grass is available, and eating pine trees is just unnecessary work. They would be out-competed by new waves of smaller beasts.
The K-T impact event cleared things out to allow adaptive radiation to fill the niches with new more advanced species. All birds today are decended from a small population of wading shore birds. If that didn't happen, replacement would be more gradual with less extreme changes over a short time. We would still have more kinds of birds, but decended from those that were wiped out in the K-T impact, instead of huge differences newly minted from recent ancestors: I'm thinking of "opposite birds" and other deeper skellital differences, more kinds of lung anatomy, flightless birds with teeth, etc. more different from having longer separate history, less different from having to repopulate all niches with the first-arrived having free reign to establish the niche rather than compete with what's already there.
What about Saurapods? Obsolete metabolism in light of new plants, so they might still be around as wood-eating fermenting vats since they have a food source the new guys ignore. They might evolve into the kind of digestive system used by cows, and take that niche with no opening for mammals which need more changing to get there.
I expect that sauropods and therapods would fill the niches that mammals do today. Today we have lions and gazelle having a common ancestor 65 million years back, and are very similar with differences bolted on to a common plan. In the alternate history, preditor and prey would be rather different kinds of animals, that diverged hundreds of millions of years ago and before establishing separarely the underlying plans; e.g. warm-bloodedness would work differently in each, the skin coverings (feathers vs ??) different, the way joints are arranged could be more different than among all mammals.
The sauropods, turning into cows and goats, would become a type not known to us, just as birds are different from mammals. They may evolve away from their herbavouious ancesstory to become widely varied; after all little shrews became all mammal varieties in our timeline. However in becoming more compact and warm blooded they would evolve a different skin covering just as feathers are different from hair. What might that be, that can serve initially as insulation and protection and (like down turning into rigid light structures) turn into something we never imagined for uses we never dreamed about.
Look at how "weird" the population of Australia's ecological niches are. Mammals that are different from dominant placentals, but still mammels and not that different. Think anout forms that are really more different, converging on the same ideas to fill a niche but vastly different in detail as penguins are from dolphins.
Even without an impact event clearing the slate, there was agency for diversity to appear as contenants pulled apart. In the heyday of dinos, all land was one place, and mostly desert in the interior. Like Australia is different due to isolated development, the raising of barriers to separate the contenents was already starting to cause differences to appear between newly separated land masses.
The oft-repeated idea of a lizard-man (in place of homonids) is wrong. They would be bird-men, not green-skinned bare-skinned lizards. Or, the new liniage that came from sauropods might take that form, and instead of hair or feathers it would be something. (Aside: bird-men would not necessarily come from what we thknk of birds today, with forelimbs modified into wings that have prooven dead-ends for returning to grasping and reaching. Therapods that did not become modern birds would have more variety and a different line, with velociraptor arms, could continue as well).
Considering that he complete evolution of feathers is seen in therapods before the available light rigid planks were used for wings, we might see such structural feathers used for other things, and evolve further in other directions that are not stressing lightness.
I hope that's food for thought. I'd love to see what undreamedof forms might be thought up by modern writers.
Not much different from today. During prehistory, mankind has exterminated or almost exterminated many threatening species -- mammoth and plenty of predators. If there was a T-Rex around in 50,000 B.C., mankind would have done something about it by 5,000 B.C.
The only alternative is that those dinos managed to exterminate the early primates. On the long run, tools and language beat sharp teeth and tiny brains.
I would say that the dinosaurs would be ruling the planet. They were becoming more intelligent near the end and another 63 million years, would have given them one heck of a head start on intelligent mammals.
I suspect that mammals would be pets of intelligent space faring dinosaurs, though with that much time, they could have left the Earth and we could have evolved after that...