Given a short bio of a person, find the minimal text span containing the date of birth of the person. The output must be the minimal text span that contains the birth date, month and year as long as they are present. For instance, given a bio like 'I was born on 27th of Decemeber 1990, and graduated high school on 23rd October 2008.' the output should be '27th of December 1990'.
Q: Philip Anthony Hopkins was born in the Margam suburb of Port Talbot on 31 December 1937, the son of Annie Muriel (née Yeates) and baker Richard Arthur Hopkins
A: 
31 December 1937