Bellard died at a care facility in Georgetown in central Texas, said Cathy Capps, director of the Texas A&M Lettermen's Assn. He had amyotrophic lateral sclerosis, a motor neuron disease also known as Lou Gehrig's disease.
Bellard was on Coach Darrell Royal's staff at Texas in 1968 when the Longhorns developed a formation with three running backs that came to be known as the wishbone.
Born Dec. 27, 1927, in Luling, Texas, Bellard coached at Texas high schools for more than two decades at the beginning and end of his career, winning three state titles from 1958 to 1966. His success landed him on the staff at Texas.
His idea was to put a third running back a yard behind the quarterback, flanked by two more running backs a few yards behind to form what looked like a Y. The quarterback had three options — hand off to the fullback, keep the ball or pitch to one of the other running backs.
The wishbone was similar to the two-back veer, which Houston was using to become a threat in the Southwest Conference. The Longhorns rode Bellard's modification to a national championship in 1969. Oklahoma made the offense nearly unstoppable in the 1980s.
"I hated him for coming up with the wishbone," former Arkansas football Coach Frank Broyles told the Austin American-Statesman in November. "We had a terrible time trying to stop it. I think it took at least four years for us to kind of slow it down. His theory was genius, and it revolutionized the game at a time when football needed it."
Former Texas A&M Coach R.C. Slocum, who was hired as an assistant by Bellard in 1972, also credited him with being among the first college football coaches in Texas to recruit black players.
"I don't think he ever got the full credit for what he really did," Slocum said.
Bellard had a 48-27 record as head coach at Texas A&M from 1972 until midway through the 1978 season, when he resigned. He led A&M to three straight bowl games, including a victory in the 1977 Sun Bowl. His record at Mississippi State from 1979 to 1985 was 37-42, with a win in the 1981 Hall of Fame Classic bowl game.
Survivors include his wife, Susan, and his son, Bob, who coaches high school football in Texas.