The world encyclopedia of dinosaurs and prehistoric creatures / Всемирная энциклопедия динозавров и доисторических существ

The science of palaeontology (the study of fossil animals) is developing at an exciting speed. New discoveries are being made so quickly, that before this book is on the bookshelves there will have been an overwhelming number of new finds and developments in the understanding of the subject. Each week there is something new to report, whether it be a skeleton that constitutes an entirely new branch of the evolutionary tree, or some indication of life gleaned through new finds of footprints or feeding traces. Microscopic analysis of fossilized dung provides ancient information about diet eaten by prehistoric creatures. Footprints tell us about the lifestyles of extinct animals.
By far the greatest number of fossils that have been found are those of invertebrate animals that lived in the sea. It is easy to understand why. Fossils are found in sedimentary rocks. Most sedimentary rocks are formed from deposits laid down on the sea bed, and so animals that lived on the sea bed would have a better chance of being buried there. There are also far more invertebrates than vertebrate species. The bodies of animals that live and die on land tend to be broken up and scavenged before they have a chance to be buried.
Our knowledge of land animals is weighted towards those that we know existed close to rivers, or in deserts, or on the banks of lakes or lagoons -places where dead bodies are likely to have been buried quickly and fossilized. We do not have direct evidence yet of the animals that lived on mountains or highland forests, or other places that were far from quick burial sites. <...>