Question

during which period did mammals first appear?
a. pleistocene
b. carboniferous
c. cretaceous
d. jurassic
please select the best answer from the choices provided
a
b
c
d

Explanation:

Mammals first appeared during the Jurassic period. The Pleistocene is much later (part of the Quaternary, associated with ice ages and modern - like mammals). The Carboniferous is known for amphibians and early reptiles. The Cretaceous had many reptiles (including dinosaurs), but mammals had already originated in the Jurassic.

Answer:

D. Jurassic