What is a noticeable difference between both eras? the paleozoic era, not the mesozoic era, had the first dinosaurs. the first mammals emerged in the paleozoic era, not the mesozoic era. the mesozoic era, not the paleozoic era, had the first animals with shells. the first flowering plants appeared in the mesozoic era, not the paleozoic era.

Transposon can cause mutations in genes at or near the site of transposon insertion. it is possible for these elements to transpose away from their original site, causing a reversion of the mutant phenotype. in some cases, however, even more severe phenotypes appear when these elements excise from this site, due to events at or near the mutant allele. what might be happening to the transposon or the nearby gene to create more severe mutations?