If thrash severed heavy metal’s roots in hard rock, groove metal succeeded in stitching them back together. Exhorder, Sepultura and Machine Head all played critical roles in the music’s early development, but Pantera deserve the biggest shout-out. When the Texans’ landmark fifth album, Cowboys From Hell, landed in 1990, it represented a startlingly fresh sound, one marrying thrash’s vile aggression with hard rock’s thick, midtempo rhythms. Key to the album’s success was Dimebag Darrell, whose pugnacious riffs and taut solos connected the dots between Metallica, ZZ Top and Van Halen. Groove metal’s impact certainly has been vast. Its heavy emphasis on rhythm informed both nu-metal’s start/stop syncopation and metalcore’s roiling breakdowns. Another crucial path for its influence has come via Lamb of God, who in the 21st century unleashed a throttling attack that helped build bridges between groove metal, death metal and hardcore punk.