I had to Google "Truth to Power" to find the meaning of the Quaker expression (tell-off the boss today, in context).

I had to Google "Taj Mahal" in London to find it's an Indian restaurant.

However, I am at a loss to figure out "BC" today. Is that a chronological series of pictures on the wall? Fishing, rock-collecting, hunting, and dancing with a dinosaur??? What's the humor in this one?