Thanks for the lively posting. And personally I know more about the Chauvet cave paintings than the ones at Lascaux.
The Chauvet cave paintings have been dated as 31,000 years old, thereby upending the field of art history. The orthodox timeline has been strained again!
This is because the Chauvet paintings are “disturbingly” modern with evidence of great artistic skill in shading, line fluidity, and perspective. The art is sophisticated—and anything but primitive.
Finally, thank goodness that the dictionary link you sent had an audio button. Otherwise, I would have been clueless about how to pronounce "chthonic". Will now plan on using it in the company of several friends with lisps who are quite accepting of weird-sounding words.