Museum of Natural History Subway Tiles

I was standing on the platform waiting for the C train to take me downtown at the NYC Museum of Natural History stop, and I looked down and saw these tiles.  There were 1 per section between the large iron beams holding the roof up.  I have no idea what they mean or what they are (or who the artist is), but they are interesting and hopefully I'll find out more about them at some point.  They look vaguely like either ancient cave paintings or possibly inuit art, I'm not sure.  There is also wall mosaic art, and a link about it here.