The origin and history of New Zealand’s terrestrial vertebrates

Since the 1980s, morphological and molecular research has resulted in significant advances in understanding the relationships and origins of the recent terrestrial vertebrate fauna in the New Zealand biogeographic region. This research has led to many taxonomic changes, with a significant increase in the number of bird and reptile species recognised. It has also resulted in the recognition of several more Holocene (<10 000 years ago) bird species extinctions. The conclusion that Holocene extinctions were primarily caused by humanhunting and predation by other introduced mammals (particularly rats and cats) has been supported by new data. Despite many local eradications of introduced pests, the number of introduced species has increased, with the establishment of five more foreign birds and (on Norfolk Island) the house gecko (Hemidactylus frenatus). Many new, significant New Zealand vertebrate fossils have been reported, including more dinosaurs from the Cretaceous, and the first Tertiary records of frogs, rhynchocephalids, lizards, crocodylians, bats and a terrestrial “Mesozoic ghost” mammal from the Early Miocene near St Bathans. For birds, the earliest known penguins in the world have been discovered, and there are intriguing Late Cretaceous – Early Paleocene remains still awaiting detailed description. Other significant Tertiary bird fossils reported include a rich avifauna from the Early Miocene St Bathans sites and a small terrestrial fauna from the Early Pleistocene near Marton. In line with the traditional theory, new research has supported the vicariant Gondwanan origin of some distinctive New Zealand terrestrial vertebrates, such as leiopelmatid frogs, tuatara and moa, and the immigration of many others, including New Zealand wattlebirds and piopio, during the Cenozoic. Extinctions caused by an asteroid impact and climate fluctuations probably explain the absence of many groups, such as crocodylians, dinosaurs, monotremes, palaelodids and swiftlets, from the modern fauna.