"Basilosaurus would be reptiles even though they are whales (mammals)"
Basilosaurus, with its elongated body, was believed to be a reptile when it was first identified, hence the name.
It was only realized years later they WERE - not are, whales.
You don't know this?
Still Homo is still the genus human still, and neanderthals were not too long ago considered a subspecies or variant of sapiens.