No, mammals lived alongside dinosaurs and their earliest known fossils of about 200 million years old are almost contemporary with the early dinosaur fossils.
The Equus genus first appeared in the fossil record around 4 million years ago during the Pliocene epoch.
Mammals first appear in the fossil record of the Mesozoic Era.
The fossil record shows that mammals and the great dinosaurs shared the same times. It also shows that mammals made a major surge in population when the dinosaurs died out.
Tiny, shrew or mouse-like creatures.
The earliest record of mammals comes from sedimentary rock. Sedimentary rocks are deposited in layers. They are an important source of natural resources, such as coal, fossil fuel, and ore.
Fossil records are not complete. By some estimates, less than 1% of organisms that have lived appear in the fossil record.
The answer is the fossil record :D
2.5 billion years ago
The first key hominid trait to appear in the fossil record is bipedalism, which refers to the ability to walk upright on two feet. This adaptation is characteristic of early hominids and distinguishes them from their primate ancestors.
Because the layer dinosaur fossils are located are from time period and the fact there were no mammals (cat like) on that time, makes it impossible for cats to be found on that layer. Actually the first mammals appear in the fossil record about the same time as the first dinosaurs, but until at the time the dinosaurs died out (65 million years ago) no mammal was quite as large as the modern cat (most were the size of rats or smaller). The first cats (and "dogs") did not appear until about 50 million years ago.
The earliest primate identifiable from the fossil record is believed to be a group of creatures called Plesiadapiforms. These small mammals lived around 65 million years ago and are thought to be ancestral to modern primates.