We all think that we know what dinosaurs look like, but no human has actually seen one. But recent palaeontological breakthroughs mean that scientists are now able to create the most accurate reproductions ever seen.
A full Tyrannosaurus rex skeleton has never been found, so how do we know what they looked like?
In 1854, the world's first dinosaur exhibition opened in Crystal Palace, South London. But by the end of the 19th Century the show had lost credibility, as scientific discoveries superseded these early impressions of dinosaurs.
Now the world's leading dinosaur scientists are working on a groundbreaking exhibition in Los Angeles, California, which aims to be the most scientifically accurate representation of dinosaurs so far.
Luis Chiappe, director of LA's Museum of Natural History, says they aim to show how "we translate the evidence that we find in the field into scientific knowledge".
The centrepiece of the exhibit will be a "growth series" of three T. rex skeletons, and it will also feature a model of a baby T. rex.
To get both models and skeletons exactly right, a huge amount of science goes into each exhibit.
The palaeontologists' starting point remains the fossilised bones uncovered on digs around the world, but it's not always fresh excavations that yield new information.
Darren Naish, a palaeontologist at the Natural History Museum in Oxford, looks for new dinosaurs in the back rooms of museums.
"You don't necessarily have to go out in the field and look for dinosaurs, you can just rummage through museum drawers and you will find something new," he says.
He and a colleague only recently found a new species tucked away in storage, and he says there are a huge number of specimens which could become new discoveries.
"We're in a golden age of dinosaur discovery, there's about 50 new species of dinosaurs named every year," he says, adding that "about 90% of all named dinosaurs have been named since about 1990".
The next step is to work out exactly what the unearthed fossils are. It can take years to clean off sediment from an entire skeleton.
Once the skeleton is ready, it needs to be pieced together and hung true to life.
Paul Zawisha is in charge of creating a custom-made steel frame for the T. rex, which needs to be strong enough to support the enormous weight of the fossils.
He says: "Most of the bones are real which makes them extremely heavy.
"We might change the toes just a little bit to give this thing a sneaking feeling, or a pausing feeling. But it's very, very subtle," says Paul.
"You might move one toe just one inch in one direction, and that changes how you visualise this whole thing," he says.
Most experts now believe that although many dinosaurs died out 65 million years ago, a few survived and evolved into modern birds.
"What it means is that because dinosaurs have living descendents, dinosaurs are not extinct, they did not become extinct at the end of the Mesozoic era," explains Luis.
"You know you have 10,000 living species of birds that are providing you an enormous amount of information that you can use to understand the biology." 
9/21/11
How do you build a dinosaur?
9:25 AM
deinalove
