In comparison to several mammalian species, reptiles and birds have very small brains, in many cases even in relation to their body mass.

How many brains does a reptile have?

Our Three Brains - The Reptilian Brain.

Do reptiles have small brains?

Brain-body data for approximately 60 reptilian taxa indicate that the relative brain size for a given body weight varies some six-fold among reptiles, with some turtles and lizards having relatively large brains and other turtles and lizards having relatively small brains.