Styles of behavioral complexity recorded by selected trace fossils

At least four styles of complex behavior are recorded in trace fossils: (1) Intricate, programmed behavior that is recorded in complex trace fossils, such as Spirophyton and Zoophycos. (2) Behavior that is complex in consisting of multiple simple behaviors performed by a single organism, as indicated by one trace fossil merging into another (compound trace fossils). (3) Behavior in which an animal constructs both complex and simple structures, as demonstrated by direct connection between the two structures. (4) Two scales of complex behavior reflected in multiple specimens of one trace fossil arranged in a pattern to produce a distinctive, larger-scale structure. Until recently complex trace fossils (e.g. Zoophycos) alone have served as proxies for complex behavior. Recognition and reconstruction of diverse modes of behavioral complexity allow more biological information to be gleaned from the trace fossil record.