Question

which mammal have nucleus in their RBCs

Answer 1

Nucleated RBCs are found in birds, reptiles, and other lower forms of vertebrates.

And from an evolutionary point of view, it could be concluded that many life forms that contain red blood cells will have a nucleated RBCs until evolution takes them into the next level, such as mammals.

However, nucleated RBCs are also found in the human fetus and newborn babies. And if they appear in adults, this can be a sign of anemia or some sort of stress upon the bone marrow resulting in a rapid production and extrusion of red blood cells into circulation. Hemorrhage being a prime example.

Also there are other conditions such as bone marrow cancer and other types of pathology resulting in nucleated RBCs in humans, and it is not a good sign.

In general, a lack of nucleated RBCs is a sign of a more advanced evolutionary species.

Answer 2

Mammal have nucleus in their RBCs.
Answer is. Camal and lama animal