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.
The iris is a flat and ring-shaped membrane behind the cornea of the eye with an adjustable circular opening in the center called a pupil. This is the structure that provides an individual with eye color. Together with the pupil, the iris is responsible for regulating the amount of light that gets into the eye.oo much or too little light can hamper vision. The muscular iris moves to shrink the pupil if there is too much light and widen it if there is not enough. This is an involuntary function, controlled by the brain. The iris is made almost entirely of connective tissue and smooth muscle fibers.