February 10, 1947: Lawrence "Butch" Morris
Also February 10, 1939: Barbara Kolb who performed at NMA 1980 Minneapolis
Lawrence “Butch” Morris
1947 Long Beach, California
https://en.wikipedia.org/wiki/Butch_Morris
His first appearance at the NMAs was at Washington D.C. in 1983, when he was already deep in the exploration of his group improvisation method called Conduction: