Comparison in a HR diagram between the [N/C] data (squares) and the predictions (circles) of solar-metallicity evolutionary models for various initial rotation rates and two cluster ages: log(t) = 7.2 (left panels) and 7.4 (right panels). The model predictions are taken from Georgy et al. (2013). The stars selected in each panel fulfil the condition |ω − ω_init| < 0.1. The observational error bars are smaller than the square symbols. The [N/C] abundance ratio is colour coded. The stars V380 Car – and to a lesser extent V405 Car – whose observations are at odds with the model predictions are indicated.