STEREOTYPICAL WEBS. “The most species-rich families within Orbiculariae are the linyphiids and the theridiids. Each has independently transformed the orb into different aerial sheets. In both cases, these webs are distinguished from ancestral sheets not only in being aerial but also in the overall stereotypy of their architectures, a characteristic inherited from orb weaving ancestors.”
http://www.pnas.org/content/106/13/5229.full