Britannica Sources used in this answer

Which animal families are absent from New Guinea despite being common in other tropical rainforests?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

World map using color coding to show the distribution of major floral kingdoms, subkingdoms, and regions. Key floral kingdoms include Boreal (green), Neotropical (pink), Paleotropical (yellow), South African or Capensic (purple), Australian (orange), and Antarctic (blue). Boundaries for subkingdoms, regions, and divisions are marked with different colored lines, and major regions such as Indoafrican, North American, and Malesian are labeled across continents. — biogeographic region Floral kingdoms, subkingdoms, and major regions of the world.

In the context of biogeographic regions, New Guinea is notable for the absence of several animal families that are common in other tropical rainforests worldwide. This distinction is largely defined by the Wallace Line, a boundary that separates the Oriental and Australian faunal regions.12

While monkeys are typical of tropical rainforests in both the New and Old World, they are entirely absent from New Guinea and areas to its east and south. Furthermore, the island is almost devoid of large mammals that are characteristic of other tropical regions, such as deer, cats, elephants, and rhinoceroses.23

These differences stem from the long-term geologic isolation of New Guinea, which has allowed its fauna to evolve independently of the Asian continent. Consequently, the island's rainforests are dominated by marsupials—such as tree kangaroos and cuscuses—rather than the placental mammal groups found in Southeast Asian rainforests. Only a few groups, such as bats and rodents, have successfully migrated across the divide to become common in both areas.423