Most New Zealand species are not very different from their close relatives in other countries. But some are primitive animals that have died out or are restricted elsewhere. Some have been in New Zealand for at least 85 million years. Others arrived after New Zealand split from Gondwana.
The speed with which introduced rats, mice, stoats and other mammalian predators have recently wiped out many native species gives a clue as to why primitive species endured for millions of years. On other land masses, more sophisticated competitors and predators evolved – primitive species became extinct as a result. These competitors and predators were absent in New Zealand, so primitive life flourished.
There are a number of primitive animals in New Zealand:
- The tuatara (Sphenodon) is the only surviving member of a reptile group that existed before the dinosaurs and was once common everywhere.
- New Zealand wrens (Acanthisitta) are the earliest passerine (perching) birds.
- Ancient frogs (Leiopelmids) and insect-like creatures, such as the Heterojapyx species, are nearly unchanged since the Jurassic period (200–145 million years ago).
- The short-tailed bat (Mystacina) belongs in a group by itself, and was unknown elsewhere until discovered as a fossil in Australia.
Few plants can be categorised as primitive survivors, although many are from old groups. Some of New Zealand’s primitive plants, such as the flowering plant hutu (Ascarina lucida), arrived recently (in the last 10 million years). Hutu is endemic – only found in New Zealand. Other primitive groups, such as podocarps, are widely distributed elsewhere.
Some features are shared by many New Zealand species, making the group distinctive. Examples are flightlessness in birds, gigantism in some animal groups, and white-flowered plants.
New Zealand, in common with other isolated archipelagos such as Hawaii, has a large number of radiations. This is when one species rapidly evolves into many species. These may be adapted to various environments, or have highly distinctive forms, behaviours or habitats.