It can't be antelope's skull. Antelope's don't have sharp teeth.It
looked more like a carnaver's skull

Scar picked up some antelope's scull that he probably most likley ate.

The jaw bit was long but the head looks too small to be a
lionns, it looks like a lion c-u-b-s.

it was just a random skull, if he hated mufassa, why would
he have his skull????

I think The Skull was just leftover from whatever Scar had
eaten a long time ago

Well i watched it again and he says,''some as big as your
head''.

...Maybe you could also like watch that part again and
listen to Scar's singing, I'd be interested to see if you
can hear Mufasa's name being mentioned, I think he says,
"But none are as big as Mufasa's head" (Roughly!)

I think Mufasa's skull, because I recall Scar singing
something about Mufasa while he was looking at the skull,
but you can't really hear it properly over Zazu's
complaining!

Well it look's like a lion's skull, so maybe it's mufasa's.

A antelopes.