40 million years ago
They started appearing in the Cenozoic period.
Mammals first appear in the fossil record of the Mesozoic Era.
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.
because it hiding in the records of the rock
Fossil records of ancient elephant species, such as Mammoths and Mastodons, show the evolution of elephants over millions of years. These records demonstrate changes in size, tusk shape, and habitat preferences, reflecting the process of adaptation and evolution. Comparing these fossils to modern elephants helps scientists understand how elephants have evolved over time.
The fossil records have eroded due to lack of proper preservation.
During the KT extinction event the majority of life on earth became extinct. Small mammals, however, were able to survive this mass extinction.
Fossil records are not complete. By some estimates, less than 1% of organisms that have lived appear in the fossil record.
Fossil records suggest that dolphins evolved around 10-15 million years ago during the Miocene epoch. They are believed to have evolved from land-dwelling mammals that returned to the sea.
According to the fossil records, the modern humans did appear on earth more than 130,000 years ago.
Mammals first appear in the fossil record of the Mesozoic Era.
resembled dogs and cats
No, mammals lived alongside dinosaurs and their earliest known fossils of about 200 million years old are almost contemporary with the early dinosaur fossils.
Mietje Germonpre has written: 'The Belgian quaternary mammals' -- subject(s): Bibliography, Fossil Mammals, Mammals, Fossil, Paleontology
William Wise has written: 'Nanette the hungry pelican' 'The world of giant mammals' -- subject(s): Fossil Mammals, Mammals, Fossil 'The cowboy surprise' 'The terrible trumpet'
Jin Meng has written: 'The osteology of Rhombomylus (Mammalia, Glires)' -- subject(s): Fossil Mammals, Mammals, Fossil, Paleontology
Many mammals appear on planet earth. Here are some of them:oxhumanpigmonkeycatdogfoxwolfantelopeelephantpolar bearhorse
Theodore Elmer White has written: 'The endocrine glands and evolution, no. 3: os cementum, hypsodonty, and diet' -- subject(s): Diet, Fossil Mammals, Mammals, Mammals, Fossil, Teeth 'Additions to the Miocene fauna of north Florida' -- subject(s): Paleontology 'The lower Miocene mammal fauna of Florida' -- subject(s): Fossil Mammals, Geology, Stratigraphic, Mammals, Fossil, Paleontology, Stratigraphic Geology