We use the spatial information of our previously published VLT/FORS2 absorption line spectroscopy to measure mean stellar velocity and velocity dispersion profiles of 25 field early-type galaxies at a median redshift z = 0.97 ( full range 0.6 < z < 1.2 ) .
This provides the first detailed study of early-type galaxy rotation at these redshifts .
From surface brightness profiles from HST imaging we calculate two-integral oblate axisymmetric Jeans equation models for the observed kinematics .
Fits to the data yield for each galaxy the degree of rotational support and the mass-to-light ratio M / L _ { Jeans } .
S0 and Sa galaxies are generally rotationally supported , whereas elliptical galaxies rotate less rapidly or not at all .
Down to M _ { B } = -19.5 ( corrected for luminosity evolution ) , we find no evidence for evolution in the fraction of rotating early-type ( E+S0 ) galaxies between z \sim 1 ( 63 \% \pm 11 \% ) and the present ( 61 \% \pm 5 \% ) .
We interpret this as evidence for little or no change in the field S0 fraction with redshift .
We compare M / L _ { Jeans } with M / L _ { vir } inferred from the virial theorem and globally averaged quantities , and assuming homologous evolution .
There is good agreement for nonrotating ( mostly E ) galaxies .
However , for rotationally supported galaxies ( mostly S0 ) M / L _ { Jeans } is on average \sim 40 \% higher than M / L _ { vir } .
We discuss possible explanations and the implications for the evolution of M / L between z = 1 and the present and its dependence on mass .