AUSTIN, Texas -- Harley Clark, the former Texas cheerleader credited with introducing the "Hook'em Horns" hand signal used by tens of thousands of Longhorns faithful over the past six decades, died Thursday at his farm outside of Austin, school officials said. He was 78.

The school didn't release details or a cause of death for Clark, who watched his hand sign become one of the most recognizable and familiar signs of support in college athletics.

Clark introduced the hand sign -- the index and pinky fingers extended and the two middle fingers tucked under the thumb -- at a 1955 pep rally. It quickly caught on and became a universal symbol for the school and its athletic teams.

Clark later became a lawyer and was appointed a state district judge in 1977. He issued a landmark decision in 1987 that declared the state's public school finance system unconstitutional because of disparities between wealthy and poor school districts, a ruling that was upheld by the Texas Supreme Court.

Clark "embodied the spirit of our beloved university," said former U.S. Sen. Kay Bailey Hutchison, a former Texas cheerleader and current president of the Texas Exes alumni group. She called the hand sign a "symbol of Longhorn pride that is recognized and shared around the globe. His love and dedication to UT-Austin will never be forgotten."

In a 2006 interview, Clark said he had wanted some kind of hand signal similar to that used by the Longhorns' rivals at Texas A&M, where the "Gig `Em" sign dating to the 1930s is a closed fist with the thumb pointing straight up. Friend Henry Pitts showed him the Longhorn sign, which Pitts made up while shadow casting.

Clark shopped it around before a pep rally as Texas prepared to play TCU, and got mixed reactions. Undaunted, he was convinced it would catch on and it did.

"It's perfect," Clark said in 2006. "It just says Texas."

It also got him in some trouble. The dean of student life lectured Clark that the signal was considered a vulgarity in Sicily and might be misinterpreted in Texas. But it was too late to stop it.

Texas fans show it during the signing of the "Eyes of Texas" before and after games, and there's seldom a touchdown where a player doesn't flash it for the cameras. Longhorns opponents liked to use it just as often, turning the signal upside down in a mocking gesture.

The sign even reached the White House. It caused a Scandinavian scandal in 2005 when President George W. Bush and his daughter Jenna, a Texas graduate, flashed the sign during Bush's inauguration parade. A Norwegian newspaper interpreted it as a sign saluting Satan.

Clark is survived by his wife Patti, and four children. Funeral services were pending Thursday.