Question: When was the  American director, producer, and screenwriter born who co-founded Amblin Entertainment?

Context paragraphs:
Kathleen Kennedy (producer): Kathleen Kandice Kennedy (born June 5, 1953) is an American film producer.  In 1981, she co-founded Amblin Entertainment with Steven Spielberg and husband Frank Marshall.  She was a producer on the 1982 film "E.T. the Extra-Terrestrial" and the "Jurassic Park" franchise, the first two of which became two of the top ten highest-grossing films of the 1990s.  Kennedy is third only to Spielberg and Stan Lee in domestic box office receipts, with over $6 billion as of December 2015.

W. Bruce Cameron: William Bruce Cameron (born 1960 in Petoskey, Michigan) is an American author, columnist, and humorist.  Cameron is most famous for his novel "A Dog's Purpose", which spent 52 weeks on the "New York Times" bestseller list and is the first book in a two book series that concludes with "A Dog's Journey".  The book is the basis for the movie version starring Dennis Quaid, Britt Robertson, Peggy Lipton, K.J. Apa, Juliet Rylance, Luke Kirby, John Ortiz and Pooch Hall, an Amblin Entertainment/Reliance Entertainment/Walden Media release in theaters January 27, 2017.

Amblin Entertainment: Amblin Entertainment is an American film and television production company founded by director and producer Steven Spielberg and film producers Kathleen Kennedy and Frank Marshall in 1981.  The company's headquarters are located on the backlot of Universal Studios in Universal City, California.

Elena Engel: Elena F. Engel is a producer/director of film, video, radio and audio for The Walt Disney Company, Amblin Entertainment, Simon & Schuster Films, UNICEF (United Nations), Western Publishing Company, National Public Radio, Warner Brothers Inc., Sesame Street, and The Disney Channel.

Frank Marshall (producer): Frank Wilton Marshall (born September 13, 1946) is an American film producer and director, often working in collaboration with his wife, Kathleen Kennedy.  With Kennedy and Steven Spielberg, he was one of the founders of Amblin Entertainment.  In 1991, he founded, with Kennedy, The Kennedy/Marshall Company, a film production company which has a contract with DreamWorks.  Since May 2012, with Kennedy taking on the role of President of Lucasfilm, Marshall has been Kennedy/Marshall's sole principal.  Marshall has consistently collaborated with directors Steven Spielberg, Paul Greengrass and Peter Bogdanovich.

The Land Before Time (TV series): The Land Before Time is an American animated television series, based on "The Land Before Time" film series created by Judy Freudberg and Tony Geiss.  It was developed for television by Ford Riley for Universal Animation Studios and Amblin Television (Amblin Entertainment produced the first film), and premiered on YTV in Canada for a test on January 5, 2007.

The Bridges of Madison County (film): The Bridges of Madison County is a 1995 American romantic drama film based on the best-selling novel of the same name by Robert James Waller.  It was produced by Amblin Entertainment and Malpaso Productions, and distributed by Warner Bros.  Entertainment.  The film was produced and directed by Clint Eastwood with Kathleen Kennedy as co-producer and the screenplay was adapted by Richard LaGravenese.  The film is about an Italian war bride, Francesca (Meryl Streep), who lives with her husband and two children on a farm in Iowa.  In 1965, she meets a "National Geographic" photographer named Robert (Eastwood) and has a four-day extramarital affair with him that changes both their lives forever.  The film earned $182 million worldwide and was well received by critics.  Streep received an Academy Award for Best Actress nomination in 1996 for her performance in the film.

Douglas Wood (writer): Douglas Wood is a writer, creative executive, director and producer.  He has been a VP of Animation Development and Production for Steven Spielberg at Amblin Entertainment, Turner Pictures, Warner Bros. and Universal.

Steven Spielberg: Steven Allan Spielberg, {'1': ", '2': ", '3': 'KBE', '4': "} , {'1': ", '2': ", '3': 'OMRI', '4': "} (born December 18, 1946) is an American director, producer, and screenwriter.  He is considered one of the founding pioneers of the New Hollywood era, as well as being viewed as one of the most popular directors and producers in film history.  He is also one of the co-founders of DreamWorks Studios.

DreamWorks Animation: DreamWorks Animation SKG, Inc. (more commonly known as DreamWorks Animation, or simply DreamWorks) is an American animation studio that is a subsidiary of Universal Studios, a division of NBCUniversal, itself a division of Comcast.  It is based in Glendale, California and produces animated feature films, television programs and online virtual games.  The studio has currently released a total of 35 feature films, including the franchises "Shrek", "Madagascar", "Kung Fu Panda" and "How to Train Your Dragon".  Originally formed under the banner of its main DreamWorks studio in 1997 by some of Amblin Entertainment's former animation branch Amblimation alumni, it was spun off into a separate public company in 2004.  DreamWorks Animation currently maintains its Glendale campus, as well as satellite studios in India and China.  On August 22, 2016, NBCUniversal acquired DreamWorks Animation for $3.8 billion, making it a division of the Universal Filmed Entertainment Group.

Supporting paragraphs: Kathleen Kennedy (producer) Steven Spielberg
Answer: December 18, 1946