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We use high-resolution K-band VLT/HAWK-I imaging over 0.25 square degrees tostudy the structural evolution of massive early-type galaxies since z~1.Mass-selected samples, complete down to log(M/M_sun)~10.7 such that `typical'L* galaxies are included at all redshifts, are drawn from pre-existingphotometric redshift surveys. We then separated the samples into differentredshift slices and classify them as late- or early-type galaxies on the basisof their specific star-formation rate. Axis-ratio measurements for the ~400early-type galaxies in the redshift range 0.6<z<1.8 are accurate to 0.1 orbetter. The projected axis-ratio distributions are then compared with lowerredshift samples. We find strong evidence for evolution of the populationproperties: early-type galaxies at z>1 are, on average, flatter than at z<1 andthe median projected axis ratio at a fixed mass decreases with redshift.However, we also find that at all epochs z<~2 the very most massive early-typegalaxies (log(M/M_sun)>11.3) are the roundest, with a pronounced lack amongthem of galaxies that are flat in projection. Merging is a plausible mechanismthat can explain both results: at all epochs merging is required for early-typegalaxies to grow beyond log(M/M_sun)~11.3, and all early types over timegradually and partially loose their disk-like characteristics.

Shape Evolution of Massive Early-Type Galaxies: Confirmation of Increased Disk Prevalence at z>1