40 million years ago
They started appearing in the Cenozoic period.
Small mammals first appeared in the fossil record during the late Triassic period, around 200 million years ago. These early mammals were generally small, nocturnal creatures that evolved from therapsid ancestors. Fossils from this time indicate that they were primarily insectivorous, adapted to a life in the shadows of larger dinosaurs. Over millions of years, small mammals diversified significantly, eventually leading to the wide variety of species we see today.
Mammals first appear in the fossil record of the Mesozoic Era.
The first primitive mammals appeared in the fossil record during the Late Triassic period, approximately 225 million years ago. These early mammals were small, shrew-like creatures that lived alongside dinosaurs. The emergence of mammals marked a significant evolutionary development, leading to the diverse range of species we see today.
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
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.
Small mammals first appeared in the fossil record during the late Triassic period, around 200 million years ago. These early mammals were generally small, nocturnal creatures that evolved from therapsid ancestors. Fossils from this time indicate that they were primarily insectivorous, adapted to a life in the shadows of larger dinosaurs. Over millions of years, small mammals diversified significantly, eventually leading to the wide variety of species we see today.
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
The first primitive mammals appeared in the fossil record during the Late Triassic period, approximately 225 million years ago. These early mammals were small, shrew-like creatures that lived alongside dinosaurs. The emergence of mammals marked a significant evolutionary development, leading to the diverse range of species we see today.
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