In Victorian times, dinosaurs were thought to look like this:
This is a Crystal Palace dinosaur, more specifically an Iguanodon. It's scaly, rather recumbent, has horns on its nose (which were later moved to its thumbs) and gives me the impression of being rather like a crocodile or a big lizard. The model was manufactured in the early 1850s for Crystal Palace in London, before the publication of Darwin's 'Origin Of Species'. There are several other such sculptures, notably Megalosaurus, thus:
Another reconstruction of a sauropod dinosaur of the time has splayed limbs like a modern lizard or tortoise, and it was once quipped that it must have lived its whole life in agony, with every joint dislocated. In other words, opinions were changing as to what dinosaurs were "really" like.
Later on, dinosaurs started to accelerate a bit. Many were stood up on their back legs, they started to bite chunks out of each other in pictures and it was decided that they were living in hot and often steamy conditions, meaning that they were able to move a lot faster than was previously assumed. Unfortunately I can't show you pictures of any more dinosaurs because unlike the ones above, these dinosaurs are copyright owing to the fact that the people who drew them haven't been extinct for very long, if at all. However, any future nerd who grew up in the '60s and '70s worth their salt will remember what dinosaurs were supposed to look like at the time, often because they'd read the 'Giant Golden Book Of Dinosaurs', probably the ultimate dinosaur book for Baby Boomers and Gen-Xers. There's an excellent page on it here, with illustrations:
Later still, they started to find fossils which were clearly very speedy indeed, notably Deinonychus, and realised that the structure of their bones was more like that of an animal which generated its own heat from within than a reptile (whatever that is - don't get me started!). It was also noticed that their footprints were not accompanied by traces of a dragging tail, and they lost another point of contact with the ground with raised tails. These are the dinosaurs of 'Hot-Blooded Dinosaurs' (http://www.amazon.com/Hot-Blooded-Dinosaurs-Adrian-Desmond/dp/0385270631) and 'The Dinosaur Heresies' (http://www.amazon.com/Dinosaur-Heresies-Robert-Bakker-Ph-D/dp/0806522607/ref=sr_1_1?s=books&ie=UTF8&qid=1350136306&sr=1-1&keywords=the+dinosaur+heresies), where all dinosaurs were seen as hot, in a parallel to the way "cool" became "hot" during that decade before returning to "cool" more recently. Reality had changed again.
Time marched on. It was decided that dinosaurs were not all warm-blooded and that it was more like the big ones being like giant compost heaps from which the heat generated by their metabolism was unable to escape due to their low surface area. Their tails stayed up though, and some of the sauropods developed whip-like abilities, making them the first animals to break the sound barrier, over a hundred million years before humans invented the bullwhip and Concorde. By the turn of this century, dinosaurs were like this:
Note the curly, whip-like tails. Incidentally, watch the dinosaur at 2:30 - it lifts its forelimbs off the salt flat. Even these dinosaurs are more bipedal than they used to be.
The Diplodocus in the Natural History Museum also had its tail raised by then.
Then it was decided that many of the dinosaurs were feathered. At first, this was just those closely related to birds. However, it turned out that the other dinosaurs also sometimes had feathers, so it seemed, and the image of dinosaurs changed again.
The upshot of all this is: what makes today's dinosaurs any more real than yesterday's? How do we know that our culture and history doesn't decide what dinosaurs are? I'm not saying they never existed at all, but it seems that truth is genuinely a very slippery concept, and science in particular is not accurate. This is not news, but it is disturbing and makes me feel like the rug is constantly being pulled out from under me. Here's an older video of mine:
The second point i'm trying to make is this. Dinosaurs are not these ancient, outmoded lizardy things which were superceded by mammals. They dominated us for over 100 million years, except that that's not true either - there were some large mammals at the time and one of them probably even ate dinosaurs. After the mammals started to diversify, i.e. after the dinosaurs' unfortunate tinkering with the asteroid which wiped them all out, dinosaurs came back as dirty great carnivorous birds which ate horses. Even after these died out, there were giant reptiles which could easily have been mistaken for dinosaurs. In Australia, one of these, Megalania, even survived until people got there, the biggest crocodile ever lived in the "Age of Mammals" and there were gigantic tortoises on islands into the Middle Ages. Therefore, the image of the dinosaur as a pathetic antediluvian beast whose time has gone is false and unfair, and we would do well to remember that our time is fleeting and we're just lucky to be here, as well as being comparable to the dinosaurs ourselves.
Then there's the issue of the Neanderthals, but that's another story.
Here's the vid: