Look at this page in English (English)

How many dinosaurs were there?

In fact, no one knows the answer. The estimates are very different. We met figures from 250 to 550 and even more (one study counted as 500,000 species). The numbers will hesitate. Many of thesedinosaurs" simply received different names on the basis of very scarce minerals, sometimes only one tooth or vertebrae. The excavations and collection of dinosaurs are often expensive. Therefore, museums and paleontologists actually received relatively few remains.

We did not meet any modern assessments, but by the end of 1981 (according to the article in the journal " Science American " ), there were only about 5,000 fragments of dinosaur skeletons.

New openings of fossils and new study of occamenalities previously classified may increase or decrease the number of known species. With a better comparison of skeletons, we sometimes find that animals previously classified as two or three different species are in fact one species. Differences in skeletal details may be caused by sexual differences (semi-dimorphysis), age, disease or other natural variations between individual individuals.