I have been reading bout chimeras ...What if we put an extinct animal's stem cell into a common animal so...

Question

Since they said u can even create humans from mouse parents since it is possible for the mouse to produce human sperm cells and egg if they actually create them...

Answer 1

A few problems:

[1] where would we get an extinct animal's stem cells from?

[2] the creation of a human embryo from an enucleated mouse egg cell has never been demonstrated beyond the blastocyst stage. It is entirely unknown whether it would continue to develop normally  beyond this point. So the same would be true for other animals.

[3] we would then need the uterus of the extinct animal to implant the embryo into (that of any other species would almost certainly fail to carry the foetus to term) - and we don't have that either.