Fossils of isolated land plant spores (Heckman et al, 2001) suggest land plants may have been around as long as 475 million years ago; Fossils of land plant spores within plant fragments (Wellman et al., 2003) date back to 425 million years ago ( these were found in Oman and appear to be liverwort-like, although elaters are noticeably absent!)
The noun PUPILLARY REFLEX has 1 sense: 1. reflex contraction of the sphincter muscle of the iris in response to a bright light (or certain drugs) causing the pupil to become smaller. Familiarity information: PUPILLARY REFLEX used as a noun is very rare. Dictionary entry details.
Video Camera Iris. The iris is an adjustable opening (aperture), which controls the amount of light coming through the lens (i.e. the exposure). The video camera iris works in basically the same way as a still camera iris -- as you open the iris, more light comes in and the picture appears brighter. The difference is that with video cameras, the picture in the viewfinder changes brightness as the iris is adjusted.