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'.

Example Input: Lange was born in Cloquet, Minnesota, on April 20, 1949
Example Output: April 20, 1949

Example Input: Hoffman was born on July 23, 1967, in the Rochester suburb of Fairport, New York
Example Output: July 23, 1967

Example Input: Page was born on February 21, 1987, in Halifax, Nova Scotia, to Martha Philpotts, a teacher, and Dennis Page, a graphic designer
Example Output:
February 21, 1987