Top panel: comparison of the M 48 CPD (circles, red online) with that of M 34 (250 Myr old; pentagons, dark blue online). We see that the M 48 sequence is clearly above that of M 34, indicating that M 48 is older. Another indicator of M 48’s older age is it’s lack of fast-rotating stars,which form a sparsely populated sequence in M 34 (with P ~ 1 d and 0.6 < (B − V)₀< 1). Middle panel: comparison of the M 48 CPD with that of the Hyades cluster (triangles, gray online). While the rotation periods of similar-mass stars are comparable between the two clusters, indicating that their ages are roughly comparable, the average solar-type M 48 star (see text) is 0.99 d below that for the 625 Myr-old Hyades, indicating that M 48 is somewhat younger. Bottom panel: comparison of the M 48 CPD with that of the 590 Myr-old Praesepe cluster (diamonds, green online), confirming that M 48 is again younger. The average solar-type M 48 star (see text) is closer (0.44 d), consonant with Praesepe’s age being slightly lower than that of the Hyades.