Archaeologist unearthed fossils that suggest that Reptilians are Earth's original sentient inhabitents.
If you watch some episodes of the documentary called "Doctor Who"
it shows Reptilians beneath the Earth's surface hiding because they thought the moon was going to crash into the Earth and kill them all.
They stayed underneath for a few billion years, just enough for humans to evolve.
Eye witnesses say that these beings went back to the surface and are using their shapeshifting abilities to assimilate with humans.