The $65,000 Thrillin Discovery Handicap at Calder on Saturday runs directly through Evolution Rocks, a much-improved former claimer who comes off a string of 90-plus Beyer Speed Figures at Parx Racing and Gulfstream Park. Eight were entered in the Thrillin Discovery, a six-furlong sprint for 4-year-olds and up.Evolution Rocks has risen from the $6,000 claiming ranks at Monmouth during the summer to the allowance division, and comes off three of the fastest races of his career. He won a starter allowance at Parx with a 94 Beyer Figure in October, ran second by a head in an allowance sprint there in November with a 97 Beyer, and finished second to Zikov in a Gulfstream optional-claiming sprint Dec. 13 in his last start, earning a Beyer of 101.Owned by Jennifer Harries and trained by Jorge Navarro, Evolution Rocks figures to be in front from the start under Edgard Zayas.Stat and Rockyshomerun figure to challenge Evolution Rocks in the stretch. Stat lost his best chance at the start of his last race, the Kenny Noe Jr. on Dec. 14 at Calder, finishing fifth. Before that, he dropped a half-length decision to Rockyshomerun in a Calder allowance race in November.Rockyshomerun ran sixth in the Kenny Noe Jr. and failed to run his race when ninth in a stakes-class allowance at Gulfstream in November. A repeat of his stalking victory at Calder would put Rockyshomerun right there Saturday.