The answer is Cenozoic in the beginning of this era there were few mammals and birds but longer down the road more animals appeared as the era continued.
And so my answer would be Cenozoic but i am not completely sure.:(
ANSWER ABOVE IS INCORRECT
Mesozoic is the correct answer small mammals evolved during the Mesozoic era, with reptiles, as did birds. The full potential and releasing of mammals came in the Cenozoic, when the mass extinction of 20% of the Mesozoic's species happened.
Mammals and birds appeared in the Mesozoic era.
The prehistoric era,just kidding look it up some whair els ok this site sucks
The Mesozoic Era.
Mesozoic(:
Mammals proliferated during the Cenozoic (recent age--since the end of the Cretaceous 65 million years ago). There were mammals before the Cenozoic, but dinosaurs were the most abundant fauna of that era. Reptiles, birds, fish, and turtles continue to exist. There are over 8000 species of birds, but fewer than 6000 species of mammals.
Birds are now classed as dinosaurs, but most dinosaurs were not birds. Neither dinosaurs nor birds are mammals.
Of course not ...no birds are mammals !!!!!!!!!!!No, they are birds.
Mammals are not covered with feathers. Mammals grow hair, but do not have to be covered with hair. Birds are covered with feathers.
No. Hawks are birds, not mammals. Although birds are warm-blooded, they do not nurse their young, and most have lighter bone structures than mammals.
Mammals have fur, while birds have feathersMammals give birth to live babies, birds lay eggsMammals feed their babies milk, birds find the babies food
No, they are birds.
No. Birds are not mammals.
Birds, mammals, fish, amphibians, reptiles, and all sorts of invertebrates.
Yes, all mammals are warmblooded vertebrates.Yes, all mammals are warm blooded vertebrates. So are birds. The difference between birds and mammals is that birds have feathers and lay eggs, while most mammals give birth to live young, and all mammals have hair and produce milk for their young.
No. They are birds. Birds and mammals are separate classes of animal.