  We obtained a total of 20 near-infrared K-band spectro-interferometric
snapshot observations of the Mira variables o Cet, R Leo, R Aqr, X Hya, W Vel,
and R Cnc with a spectral resolution of about 1500. We compared observed flux
and visibility spectra with predictions by CODEX 1D dynamic model atmospheres
and with azimuthally averaged intensities based on CO5BOLD 3D dynamic model
atmospheres including convection. Our visibility data confirm the presence of
spatially extended molecular atmospheres located above the continuum radii with
large-scale inhomogeneities or clumps that contribute a few percent of the
total flux. The detailed structure of the inhomogeneities or clumps show a
variability on time scales of 3 months and above. Both modeling attempts
provided satisfactory fits to our data. In particular, they are both consistent
with the observed decrease in the visibility function at molecular bands of
water vapor and CO, indicating a spatially extended molecular atmosphere.
Observational variability phases are mostly consistent with those of the
best-fit CODEX models, except for near-maximum phases, where data are better
described by near-minimum models. Rosseland angular diameters derived from the
model fits are broadly consistent between those based on the 1D and the 3D
models and with earlier observations. We derived fundamental parameters
including absolute radii, effective temperatures, and luminosities for our
sources. Our results provide a first observational support for theoretical
results that shocks induced by convection and pulsation in the 3D CO5BOLD
models of AGB stars are roughly spherically expanding and of similar nature to
those of self-excited pulsations in 1D CODEX models. Unlike for red
supergiants, the pulsation- and shock-induced dynamics can levitate the
molecular atmospheres of Mira variables to extensions that are consistent with
observations.
