Thomasson, an architect of the sound that produced the 1970s rock anthems “There Goes Another Love Song” and “Green Grass and High Tides,” died Sunday of an apparent heart attack at his home in Brooksville, north of Tampa. His death was reported on the band’s Web site Tuesday.

Thomasson was a teenager when he joined the Tampa-based band in the late 1960s. After a breakup and a couple of lineup changes, the group reformed in the early 1970s and released its debut album, “The Outlaws,” in 1975.

The album spent weeks on the charts and established The Outlaws as one of the pioneers of the Southern rock sound alongside such bands as Lynyrd Skynyrd, The Marshall Tucker Band and The Allman Brothers Band.

The Outlaws recorded more hit albums and toured extensively before disbanding in the 1990s, when Thomasson was offered a spot in the revamped Lynyrd Skynyrd. He left that group in 2005 to reform The Outlaws, which toured regularly in recent years.

Thomasson recently produced a new CD for the band, surviving members said.

All dates on The Outlaws’ current tour have been canceled until further notice.