time span simulated ( fig. S6 and table S8 ). These results, combined with the lack of resolution within superclades of the metazoan tree, argue against models of metazoan radiation in which the temporal window of diversification is much larger (48). 39. of-fit test using parametric bootstrapping (15) showed that even the best-fit model of sequence evolution does not adequately describe the evolution of the sequence data from these 32 fungal and metazoan taxa ( fig. S8 ).