Why were dinosaurs not discovered earlier?

Dinosaurs were unearthed by humans over the centuries but they were not recognised for what they were. It is almost certain that the Chinese discovered dinosaur remains over 3000 years ago, judged by reports of 'dragon's teeth' which were collected for medicinal reasons in parts of china now known to be quite rich in dinosaur bones. However there were various barriers that had to be overcome before fossils, and especially dinosaurs could be recognised. One of the biggest barriers was religious teaching, and it was not until scientists began to challenge religious teaching about the history of the Earth that this could be over-come. Also until certain skills such as comparative anatomy had developed, and scientists had become sufficiently familiar with the range of animals living today, it was impossible to appreciate the meaning of fossils. Once fossils began to be recognised as the remains of once living creatures, which was only at the beginning of the 19th century (less that 200 years ago), then the recognition of special sorts of fossils such as dinosaurs became a possibility.