How does parallel evolution explain similarities between Australian marsupials and placental mammals?

Parallel evolution describes the independent development of similar traits in geographically separated groups that occupy comparable ecological niches. In the context of morphology, this process explains why Australian marsupials and placental mammals elsewhere exhibit striking physical resemblances despite their distinct evolutionary lineages.123

Because these mammals evolved in similar environments, they faced comparable selective pressures, leading them to adapt in ways that resulted in analogous body structures and behaviors. This is so pronounced that many marsupials are named after their placental counterparts, such as the marsupial "mole," "mouse," or "cat". While these resemblances are often categorized under convergent evolution—the broader tendency for unrelated organisms to adapt similarly to identical habitats—they serve as a primary example of how independent lineages can arrive at remarkably similar forms when filling the same ecological roles.342