This is an incredible finding indeed.  The ancient burial site in question was discovered back in 1999 in Sonora, Mexico, but only recently were the 25 skeletal remains unearthed.  Out of the 25 skulls dug up, 13 of them have deformed heads.  The shape of the 13 skulls resemble those of alien heads often depicted in sci-fi films.  

However, don't get your hopes up that further evidence of alien life has been discovered just yet.  According to the Science Channel's Ryan Matthew, the intentional deformation of the skulls began in early childhood.

"When you were a newborn baby, you would be cradle-boarded.  They would put two boards around the head and wrap it very securely. Because the head of a child is very soft, it can be manipulated forward, but the process would take several months."

This may seem like an odd practice to many living in the modern world, but it was actually common practice for various cultures centuries ago.  The skulls discovered date back to between A.D. 940 and 1308.