A miniscule optimized visual system in the Lower Cambrian

摘要

Simultaneously with the development of animal body plans, probably before the Precambrian, there was an explosive diversification of visual systems. Competition of performance in these visual systems was a critical factor in the evolution of life systems. Here we analyse the visual system in the lobopod Miraluolishania haikouensis (Liu et al., 2004) from the Lower Cambrian Chengjiang Lagerstatte, Kunming, China. It consists of a very small eye with a miniscule lens. A physical problem lies in the fact that due to the usual refractive conditions of such a lens, it hardly represents an improvement of the visual quality over the basal pit- or pinhole camera eyes. To develop such a lavish visual system, however, would not have been of any value, if it achieved no more than an equal level or represented even a retrograde step in evolutionary progress. We show how this system may have allowed pattern recognition even under poor light conditions. Optimization of such a tiny eye is costly but is not 'a wasted effort' in evolution. In M. haikouensis (Liu et al., 2004), an excellently adapted miniscule visual system has become possible.