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We present the analysis of a large sample of early‐type galaxies (ETGs) at 0 &lt;  z  &lt; 3 aimed at tracing the cosmic evolution of their size and compare it with a model of pure dissipationless ( dry ) merging in the Λ cold dark matter (ΛCDM) framework. The effective radius   R  e   depends on stellar mass  as  with α∼ 0.5 at all redshifts. The redshift evolution of the mass‐ or SDSS‐normalized size can be reproduced as ∝(1 + z ) β  with β∼−1, with the most massive ETGs possibly showing the fastest evolutionary rate (β∼−1.4). This size evolution slows down significantly to β∼−0.6 if the ETGs at  z  &gt; 2 are removed from the sample, suggesting an accelerated increase of the typical sizes at  z  &gt; 2, especially for the ETGs with the largest masses. A pure  dry  merging ΛCDM model is marginally consistent with the average size evolution at 0 &lt;  z  &lt; 1.7, but predicts descendants too compact for  z  &gt; 2 progenitor ETGs. This opens the crucial question on what physical mechanism can explain the accelerated evolution at  z  &gt; 2, or whether an unclear observational bias is partly responsible for that.

Fast evolving size of early‐type galaxies at z > 2 and the role of dissipationless ( dry ) merging