Geological tales
Australia has its classical animal icons – kangaroo, crocodile, the barrier reef. New Zealand has its famous species – kiwi, kakapo, no land mammals. To understand how these two lands came to be, and are similar in both having fun very unique fauna, compared to say Africa or the Americas, we need to go back in time, geological journey. The answer truly lies in the rocks.
Tectonics
It begins with Gondwana – both what was to become Australia, and was to be known as New Zealand, in the same corner.
Australia breaks away from Antarctica, some 180 years ago, moves and grows from west to east, then much later huge forces on its far eastern side pull and stretch to become the Australian Alps
About 80 million years ago, a spreading ridge (in red above) caused what was to become Tasman Sea and the future New Zealand formed. Note that the lower part of future NZ is parallel to Antarctica. Finally, the Southern Alps in NZ’s South Island happened 5 million ago, as Australian and Pacific plates collided (note neither is called NZ plate ).
Resulting unique creatures
So, the above journey of the land explains why so many of Australia fauna – some 83% of mammals, 89% of reptiles, 90% of fish and insects and 93% of amphibians – are ‘endemic’ to Australia – they are found nowhere else. The continent’s long geographic isolation, tectonic stability, and the effects of an unusual pattern of climate change on the soil and flora over geological time – parts of Australia were covered by ice for years.
Another result is – the scarcity of native placental mammals, means marsupials – a group of mammals that raise their young in a pouch, including the macropods, possums and dasyuromorphs – here occupy many of the ecological niches placental animals occupy elsewhere in the world. Australia is home to two of the five known extant species of monotremes and has numerous venomous species, which include the platypus, spiders, scorpions, octopus, jellyfish, molluscs, stonefish, and stingrays. Uniquely, Australia has more venomous than non-venomous species of snakes. (Source – Wikipedia ) . The crocodiles in Australia- thats another post.
New Zealand fauna is , like Australia, also has creatures that arrived in unique ways. The animals of New Zealand, part of its biota, have a particularly interesting history because, before the arrival of humans, less than 900 years ago, these islands had only fauna that could swim there – seals, sea lions, and, whales, or fly there – bats and many birds.
This meant that all the ecological niches occupied by mammals elsewhere were occupied by either insects or birds, leading to an unusually large number of flightless birds, including the kiwi, the weka, the moa (now extinct), and the kakapo. ( source – Wikipedia)
The reality of being a New Zealand bird, then mammals arriving and becoming threatened… Read “wildlife rescues by Department of Conservation in an upcoming chapter”
The floras have some similarities in plants that blew across ….. thats for another chapter.
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