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New Zealand evolutionary evidence from the Cambrian
Period: During the Cambrian, evolution was rapid and within
a few million years the Earth was populated with many animal groups.
Fossils found elsewhere indicate that the marine ancestors of New
Zealand's ancient land dwelling caterpillar-like Peripatus
were alive at that time. Cambrian deposits in the Cobb Valley, in
north-west Nelson of the South Island are the oldest accurately
dated geological formations in New Zealand. Some associated sequences
occur in small areas in the southwest of Fiordland. The fauna typically
consist of Trilobites, Brachiopods, Sponges and Ostracods. Be aware
that the rocks in the Cobb Valley are protected and specimen cannot
be removed.
New Zealand fossils from the Ordovician
Period: During the Ordovician New Zealand was situated about
20° north of the equator. All life on Earth was still in the sea.
The sediments that were to become New Zealand formed a shallow sea
shelf off the coast of Gondwana. Well defined Ordovician rocks,
characterised by Graptolite
faunas
can be found in the Nelson region and the south west of Fiordland.
New Zealand fossils from the Silurian Period:
By Silurian
times Gondwana had brought New Zealand into the southern Hemisphere.
As marine creatures began to adapt to changing temperatures and
salinity, they were preparing themselves for life on land. At Hailes
Knob, to the west of Motueka a few Silurian fossils, shellfish and
trilobites have been found. There is a boulder by the roadside before
the entrance to the Takaka Gorge, in the Cobb Valley, Nelson, which
shows folds of marble and sandstone. It is possible to see a few
tiny shellfish and crinoid stems in this rock.
New Zealand fossils from the Devonian Period:
Today there
are only two small areas of Devonian rocks to be found in New Zealand,
the Baton formation, north-west of Nelson and the Reefton Mudstones
and Limestone in the South Island. Devonian corals in the region
indicate that the seas were warm. Approximately 6.5 kilometres southeast
of Reefton and 1.4 kilometres from Lankey Creek, the main road
to Lewis Pass cuts through a dark limestone bluff beside the Inangahua
River, where corals can be seen in the limestone. Some Devonian
fish have been found in rocks of the Waitahu Valley, near Reefton.
New Zealand fossils from the Carboniferous
Period: The Carboniferous period of Gondwana produced immense
coalfields in Australia. New Zealand was back then still submarine
and continued a movement to the south. The seas around New Zealand
were very cold, forcing the sea life to adapt or die. The New Zealand
seascape, lying off the south eastern coast of Gondwana included
a chain of volcanic islands that were very active late in the period.
This volcanic activity probably obscured any deposits of sediments
of that time, explaining the absence of Carboniferous rocks in New
Zealand.
New Zealand fossils from the Permian
Period: Permian rocks are widely distributed in New Zealand's
South Island and also occur in the Northland region of the North
Island, where they are the oldest known rocks. In some places the
deep sedimentary marine series that was laid down is up to 20 kilometres
thick and one of the most complete Permian sequences preserved anywhere
in the world. The biggest build up of volcanic rocks made the Takitimu
Mountains near Redcliff, Waiau Valley, where the pile of tuff layers
is 14 kilometres thick. Unfortunately Permian fossil outcrops are
hard to find, but at Arthurton, near Gore, complete shells of Atomodesma,
a bivalve, can be found. And of course a whole leaf of the Glossopteris
plant has been found at Productus Creek.
New Zealand fossils from the Triassic
Period: New Zealand was still mainly a marine environment, but
parts began to rise out of the sea, while volcanic activity continued.
Some of the ancient forms of kauri, rimu, totara and kahikatea trees
colonised the land. In the rocky shore platform at Kiritehere Beach
on the Waikato west coast, beds of a scallop-like bivalve, Monotis
and prehistoric mussels can be found. No terrestrial vertebrates
were preserved in the sediments, but Ichthyosaurus a marine
reptile has been found in the Mt Potts region in the South Island.
And at Nothosaur Stream, Mt Harper, Canterbury, a
Nothosaur,
a primitive amphibious sea lizard has been found.
New Zealand fossils from the Jurassic
Period: In the Jurassic sediments that had accumulated
offshore between the east of Antarctica and the west of Australia
were squeezed together by several tectonic plates. They were
consolidated and pressured into huge folds and uplifted and
formed a New Zealand microcontinent called Tasmantis. It is
likely that plants and animals travelled freely across the
land and the subsequent isolation of New Zealand suggests
that the archaic frogs, large land snails,
tuatara
and peripatus are all living fossils that stem back from those
times. An ancestor to the New Zealand
Weta
has been found in late Jurassic rocks at Port Waikato. The
first late Jurassic dinosaur was found in the Huriwai Plant
Beds. The bone that is similar in shape and size to that of
a Compsognathus is very rare but indicates that dinosaurs
were living around New Zealand.
New Zealand fossils from the Cretaceous
Period: About 120 million years ago waterways developed between
the edge of Gondwana and the new uplifted Tasmantis including the
piece that became New Zealand. Because of the increasing distance
that separated ancestral New Zealand from Antarctica the biota it
took was purely Cretaceous which subsequently experienced an evolution-in-isolation.
Some of the Cretaceous concretions contain bones of marine reptiles.
In inland Hawkes Bay enough bones have been collected to identify
a new species of
mosasaur.
Also a single vertebra was found to be that of an upright carnivorous
land dinosaur. At Oaro, south of Kaikoura, the sea is eroding late
Cretaceous rocks just north of Amuri (or Haumuri) Bluff. They contain
layers of belemnites, bones and shark teeth. Examples for K-T boundary
can be seen in the rocks of the Te Uri Stream in Hawkes Bay and
in Waipara, North Canterbury as well as south of Chancet Rocks at
Woodside Creek. However in all those three locations the passage
of time is shown by microscopic fossils, mostly Foraminifera which
are intercepted by a layer of clay that contains Iridium.
New Zealand fossils from the Paleocene
Epoch: During the early Palaeocene the seafloor spreading in
the Tasman Sea had stopped. Much of the New Zealand landscape eroded
away and sank. This happened probably because New Zealand's now
separated crust was thinner (about 26 km) than that of the Gondwana
landmass (about 37 km). New Zealand fossils from the Palaeocene
include the marker fossil Conchorthyra, an ancestor of
the ostrich foot shell which survived throughout the K-T events.
Another survivor of the K-T boundary were turtles which lineage
goes back 230 million years. Fossil turtles bones have been found
in New Zealand from Cretaceous up until Miocene rocks.
New Zealand fossils from the Eocene
Epoch: At the beginning of the Eocene, New Zealand and New Caledonia
were remotely connected by a series of islands, sharing plant and
animal life from their joint Gondwana heritage. New Zealand continued
to erode and sink while drifting into a warmer climate. This is
the time when the coalfield of Huntley and the natural gas and oil
fields of southern Taranaki were formed. Leaves of pohutukawa and
rata, manuka, kanuka and eucalyptus have been found in Eocene coal
deposits as well as fossil pollen of Seaforthia the ancestor
of the nikau palm tree. New Zealand's ancient whales such as Basilosaurus
were long slender giants whose vertebrae and teeth are occasionally
found in Eocene limestones of South Canterbury.
New Zealand fossils from the Oligocene
Epoch: Two thirds of modern day New Zealand were submerged during
the Oligocene, the movement of the tectonic plates in the north
of New Zealand caused big areas of oceanic crust to be subducted,
pushed into as well as over the northern and western parts of the
North Island. The little land that was left during the Oligocene
was home to a decreasing number of species. Many died but some snails,
peripatus, frogs, tuatara and ratites survived. A similar scenario
happened to the plants on land, and here the warmth loving beech
trees became dominant. Large sea urchins, giant oysters, crayfish,
molluscs and giant sharks (up to 13 metres) thrived in the shallow
seas. The fossilised shells of giant oysters can be found in limestones
on the Coromandel Peninsula at Waitete Bay in the shore platform
at low tide.
New Zealand fossils from the Miocene
Epoch: Around the mid-latitudes of the Southern Hemisphere prevailing
westerly winds established during the Miocene. These winds, and
the associated ocean currents, aided the transfer of Australian
plants and animals across the Tasman Sea, and have been very important
in bringing South American taxa to Australasia e.g. kowhai (Sophora)
has salt-resistant seeds and colonized New Zealand from Chile. The
long-tailed bat reached New Zealand from Australia in the Miocene,
as did the geckos and the ancestor of the takahe, which later evolved
both gigantism and flightlessness as adaptations to island life.
In the seas, the giant crab Tumidocarcinus giganteus, five
times the size than the modern purple rock crab, flourished. Fossilised
crabs have been found near Taumaranui in the North Island and Motunau
and Glenafric in the South Island.
New Zealand fossils from the Pliocene
Epoch: New Zealand's geography changed rapidly during the Pliocene.
There was widespread volcanic activity, particularly in the North
Island (although Banks Peninsula and Port Chambers, both volcanic
calderas, formed at this time), and both the Southern Alps and the
Kaikoura Ranges began to form. This was important in the evolution
of New Zealand's plants and animals as it split the South Island
longitudinally into a wetter western side and a drier, flatter eastern
side. The late Pliocene was also a period of rather high sea levels,
so that NZ was divided into a series of islands. The consequent
isolation of species populations that could then diverge into separate
species or subspecies accounts for some of the biodiversity and
also many of the distribution patterns of our modern biota. The
Hebe family made its first appearance during the Pliocene while
many warmth loving plants were extinct. Fossils of giant spider
crabs have been found in the Wanganui River, Cape Kidnappers and
in rocks of inland central Hawke's Bay. Theses animals preferred
deep, cold water and are an indication that New Zealand's climate
was moving towards an Ice Age.
New Zealand fossils from the Pleistocene
Epoch: Throughout the Pleistocene there were about twenty cycles
of cold glacial (Ice Age) and warm interglacial periods at intervals
of about 100,000 years. During the Ice Ages glaciers dominated the
landscape, snow and ice extended into the lowlands, transporting
huge quantities of rock with them. During these periods the South
Island was extensively glaciated, and there were small glaciers
on the Tararua Ranges and Central Plateau. Because a lot of water
was locked up in ice, the sea levels dropped during the glacials
(up to 135m lower than at present). Extensive land bridges joined
the main and many offshore islands, allowing the migration of plants
and animals. During the warmer periods large areas became submerged
again under water. These repeated episodes of environmental fragmentation
drove rapid adaptive radiation in many NZ species, especially (but
not exclusively) the alpine plants.
Coastal areas such as Hawke's Bay, Bay of Plenty, Wairarapa, Wanganui, Marlborough and North Canterbury have only been pushed up to become land in the last 50,000 years. Rich deposits of beautifully preserved Pleistocene sea shell fossils can be found from Te Piki (East Cape), Te Mata Peak, Cape Kidnappers and Castlecliff (Hawke's Bay), Castlepoint (Wairarapa Coast), Hawera and Wanganui, Motunau Beach (Marlborough) and at Titarangi, (Chatham Islands). They are evidence for shallow, sandy bottom seas. The cliffs of the Rangitikei River represent layers of Plio- and Pleistocene rocks, uplifted sea floors that have been eroded by the river exposing many shell and mollusc fossils.
New Zealand fossils from the Holocene
Epoch: The Holocene period represents the last 8,000 years,
a very short time for fossils to form. Holocene fossils are often
modern species that have fallen down holes into underground caves
and been preserved. Extinct species like the Moa, the giant eagle,
a native goose, reptiles, frogs and bats have all been found in
Holocene limestone caves. Fossil bones of the king shag, Leucocarbo
carunculatus, are reported from the late Holocene dune deposits
of Tokerau Beach, Doubtless Bay, Northland.
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