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 color of the iris gives the eye its color. In optical terms, the pupil is the eye's aperture and the iris is the diaphragm that serves as the aperture stop.he iris develops from the anterior two layers of an embryonic neuroectoderm structure called the optic cup. The optic cup also produces the iris sphincter and dilator muscles.