German researcher Dr Michael Rappenglueck, of the University of Munich, has suggested that drawing on the wall of the Lascaux caves in France could be a graphical representation of the Pleiades open cluster of stars. This is dated from 33,000 to 10,000 years ago. He also suggested a panel in the same caves depicting a charging bison, a man with a bird's head and the head of a bird on top of a piece of wood, together may depict the Summer Triangle, which at the time was a circumpolar formation. Rappenglueck also discovered a drawing of the Northern Crown constellation in the cave of El Castillo (North of Spain), made in the same period as the Lascaux chart.