I actually went and read the article they linked. Apparently it's a Chinese blogger making the claim... someone named Zhao. Basically, they found a painting of the Xenomorphs in a flea market and seems to think it's the art of one Qi Baishi, an artist who died in 1957.
I don't think there's proof, nor has the painting even been taken to a specialist to be analyzed... I don't think the picture is even signed by Qi Bashi. However, I don't know anything about Qi Bashi, or this Zhao person. Is Zhao someone with an art doctorate and a way to test the age of the paint? Is this the kind of art of which Qi Bashi has other examples?
It's very clearly a picture of Xenomorphs... suspiciously just like them. That, honestly, makes me a bit skeptical about their authenticity. But as I said, I don't know enough.
...
>.>
IT'S A FAKE! THPPPPPT!
Also, I have never watched Aliens.