Assertion: nervous system's type | /r/CapableOf | lack central nerve cord
Facets:
Source sentences:
text: On one hand, the presence of a shared set of genetic markers, as well as a tripartite brain structure shared by widely separated species (Hirth, 2010), suggest common derivation; on the other hand, the fact that some modern types of bilaterians (such as echinoderms) lack a central nerve cord, while many lack recognizably tripartite brains, suggest that this might have been the primitive state (Northcutt, 2012).