The Meg

Often an object has a much wider story to tell than what can be seen at face value, as interesting as that can initially appear.  Part of the fun in researching it is uncovering the wider back story which helps to build up a bigger picture of where we stand at the present.

So with that in mind, how did a tooth from a megalodon end up in the riverbed near Whanganui?

2. Megalodon size

The Megalodon at the top, compared to a Great White Shark and a Human. Image sourced through Creative Commons.

The largest known shark, the Carcharodon megalodon lived from 16-2.5 million years ago. The megalodon was related to the Great White Shark of today but was huge. Fossil remains show the megalodon was an average size of 10.5 metres long but could grow up to 18 metres. An adult human could easily sand up in its jaws which measured over two metres wide.

The particular tooth in the Museum collection measures 13.5 centimetres high and 11.5 centimetres wide. It was found near Pīpīriki in a bank of sandstone estimated to be four to five million years old. Because of its marine past, Whanganui is a great place to find marine fossils, in particular fossilised shark teeth.

1. Megalodon tooth

The Megalodon tooth found near Pipiriki. WRM Ref: 1800.175

About 540 million years ago, New Zealand was being formed on the eastern edge of the supercontinent Gondwana. This continent included what we know today as Australia, Antarctica, India, Africa and South America.

Around 100 million years ago, hot rock began to accumulate underneath Gondwana and move towards the edges of the land, pulling it apart. This slowly made a giant rift which allowed the sea to flood in, and separated it from the mainland, thus creating the continent of Zealandia. After breaking away from Australia around 85 million years ago, Zealandia largely sank beneath the Pacific Ocean. What remains visible today is essentially the highlands of the continent, and the rift is now the Tasman Sea.

Zealandia sits across the edge of the Australian and Pacific tectonic plates and is slowly being broken up as they continue to move. The last 1.8 million years have shaped the land with tectonic movements, glaciers and volcanoes, altering the landscape. Whanganui, being on the coast of New Zealand and consisting of lifted sea beds, is more likely to reveal marine fossils.

The hinterland areas are fertile with volcanic ash at the core. The mountains in the north and west help to shelter the township and have created a wonderful climate, much warmer and drier compared to other coastal towns.

Before human settlement, this land was covered with forest: tōtara, matai, rimu, tawa and beech trees covered the landscape. The soft rock near the coast was easily worn down by water, and helped to create the Whanganui River, the longest navigable waterway in New Zealand, measuring 290 kilometres from its source at Mount Tongariro.

All this adds up to a beautiful place with fertile lands, fresh water, ocean access and a temperate climate, which made it perfect for settlement when Māori arrived.


Sandi Black is the archivist at Whanganui Regional Museum.

Fossil Giant Crab

In 1990, a local Whanganui resident captured a giant crab in the Ahu Ahu Valley, inland from Whanganui. That’s a curious creature to find so many kilometres from the coast. It was, however, not a potential family feast. It was a large fossil embedded in a spherical boulder, known in geological terms as a concretion. A concretion is a hard rock that forms around an object such as a fossil, protecting it from damage. Concretions can often be found weathering out of soft mudstone. If a concretion is cut open very carefully, it may reveal an interesting fossil, well preserved within the boulder. Because mudstone is very soft, it can be generally be cleaned off the fossil using water and a stiff brush.


Tumidocarcinus giganteus, giant fossil crab. WRM ref: 2003.42.1

This particular fossil crab was alive approximately 15 million years ago, during the middle of the Miocene period, when the Ahu Ahu Valley, along with the rest of the Whanganui region, was under the sea. It is an example of the extinct species Tumidocarcinus giganteus, a deep-water crab that lived along the seabed in warmer waters than we enjoy today, on the Whanganui coast. During the middle of the Miocene period, which lasted from 24 million years ago to 5 million years ago, temperatures are estimated to have been four to five degrees warmer over most of the planet than they are today, and the sea level was correspondingly much higher.

Large numbers of Tumidocarcinus giganteus fossils have been recovered from the soft papa rock that is characteristic of the hills between Taranaki and Whanganui. Papa is formed from thick muddy sediments accumulating in the ocean around the western coast of the North Island. The numbers of these crabs found indicates that they were a reasonably common species in New Zealand seas during the Miocene. An interesting feature of the Tumidocarcinus giganteus is that the right pincer is usually much larger than the left. On males, the right claw could grow up to twice the size of the left claw. It was probably used for fighting and perhaps for attracting female crabs, as well as feeding.

By discovering fossils, such as this giant crab a very long way from the ocean, we can get a much clearer picture of what the land-masses we now inhabit might be like if the earth’s climate became similar to the middle Miocene again. It is challenging for us to imagine what the planet might be like if temperatures throughout the world continue to rise at the current rate. It is clear, however, that seas will be significantly higher, and much of the New Zealand land mass, especially coastal regions, will probably be under water.

The Whanganui region probably won’t be so great for humans, but giant crabs and other enormous sea creatures might be plentiful again.

Margie Beautrais is the Educator at Whanganui Regional Museum

King Penguin: a Royal Line in Trouble

New Zealand was once home to a gigantic species of penguin, as tall as an adult male human. Like many megafauna species of the planet, this species is now extinct and exists only as fossil remains held in museums.

Two other very large penguins, the Emperor penguin and the King penguin, live in huge colonies around the southern seas. They were so numerous that it appeared there was no risk of them following New Zealand’s fossil Giant penguin into extinction. This, however, may no longer be true of the King penguin. The once numerous bird may be already be an endangered species. The end of the current century, according to scientific research, might signal the end of this royal branch of penguins through the effects of climate change on ocean currents and sub-Antarctic habitats.

1. King penguin with egg

Taxidermied King penguin with egg. Ref: 1802.1688

King penguins live and breed between latitudes of 45 and 55 degrees south, on sub-Antarctic islands and northern parts of Antarctica. The most numerous colony, with about half of the global population of King penguins, has historically been the Crozet Islands in the Southern Indian Ocean. In 1982 the King penguin population of these islands was estimated, through aerial survey, to be around two million individuals. Recent analysis of satellite images taken over the last thirty-five years indicates that the population has plummeted by 90% to around 200,000 birds, with just 60,000 breeding pairs. While this is still a very large number, such a rapid decline is concerning. So what has changed?

Researchers suggest the causes may be overcrowding and the resultant competition for resources; disease such as avian cholera; or the possible arrival of invasive pest species. A non-migratory species, such as the King penguin, relies on the continued health of its sub-Antarctic habitat for survival. King penguins leave their young and swim south to forage for fish and squid along the polar front, where cold, deep water meets more temperate sea.

2. King penguin egg

King penguin egg. Ref: 1802.5822

The research team suspects that climate change could be contributing to the decline, as it has with colonies of penguins in parts of Antarctica. In 1997, a strong El Niño weather event warmed the southern Indian Ocean and temporarily pushed fish and squid, normally eaten by King penguins, further south, beyond their foraging range. The result was population decline for all King penguin colonies in that region. Although El Niño events are cyclical, they can be amplified by global warming. The researchers have concluded that based on current climate change predictions the Crozet Islands, once home to half the world’s population of King penguins will become uninhabitable for these penguins by the mid-century.

With nowhere else to go, the Crozet Islands population of King penguins will be in serious trouble. It would be such a shame if one of the world’s most iconic and loved penguins exists only as taxidermied specimens in natural history museums.


Margie Beautrais is the Educator at Whanganui Regional Museum.

Stories from bird bones



Most of us associate kea with holidays in the Southern Alps. When you stop the car at Arthur’s Pass a few of these parrots will normally arrive to fearlessly beg for food. Cars and food are so strongly associated in their minds that they’ll tear the rubber trim off your vehicle in the hope that snacks might be found somewhere inside. Kea are remarkable birds, intelligent and inquisitive, and are famous among ornithologists for being the world’s only alpine parrot.

To a palaeontologist, though, kea aren’t alpine parrots at all. Fossil kea bones, many just a few hundred years old, have been found in lowland sites thoughout Canterbury and Otago right down to the coastline, showing the birds were living in coastal forest before humans arrive. Even today, kea live year-round in forest in parts of the West Coast. And new research has identified kea bones from swamps and sand dunes in Hawkes Bay and the Wairarapa, so it seems likely that were living in North Island forests as well.

Kea, Kākā, and Chatham Kākā  skulls

Kea, Kākā, and Chatham Kākā skulls

So where did all the kea go? They were probably wiped out by the first human settlers and the rats that accompanied them around 700 years ago, disappearing from the North Island and most of the South Island. The only reason kea aren’t extinct is that the Southern Alps are inhospitable to both rats and humans. But the upside is that kea could likely be reintroduced to North Island forests where there’s sufficient predator control—good news for mainland islands like Zealandia and Bushy Park.



Kea are not the only case where fossil bones tell us where a species used to live. Huia at the time of European settlement were restricted to the south-eastern North Island, mostly in the Tararua, Ruahine, and Rimutaka ranges. But their bones have been found right up to Northland, and they were probably found throughout the island before human hunting made them rare (and, by about the 1920s, made them extinct).

Takahē were once found throughout the South Island. Thought to be extinct by the 20th century, they were famously rediscovered in an Fiordland valley in 1948. Their northern cousin, the moho or mohoau, is known only from fossil bones from all over the North Island, although a single live bird was caught in the Tararuas in 1894. Both takahē and moho were the giant flightless descendants of pukeko, and both were driven almost to extinction in pre-European times; it’s just a fluke that the South Island takahē managed to survive while their relatives went extinct. Like the kea, takahē persisted in an inhospitable environment, but they much prefer living in lowland forests, given how well they do on offshore islands and mainland sanctuaries.

Chatham Kākā

Chatham Kākā

Fossils not only shed light on living species; they sometimes reveal brand new ones. For years, palaeontologists had been turning up bones of kākā in the Chatham Islands, except these kākā had unusually long beaks; almost as long as a kea’s. After comparing bones, they realised the Chatham kākā was a completely separate species: a ground-dwelling version of the mainland kākā, wiped out soon after humans arrived in the Chathams. The Chatham Islands turn out to been like mainland New Zealand in miniature, full of species found nowhere else. The islands had their own species of pigeon, robin, fernbird, penguin, bellbird, swan, coot, and other flightless rails; most of these are now extinct or endangered, a few, like the Black Robin, were rescued in the nick of time.



It’s remarkable that we’re still making discoveries about some of our most well-known native birds, from such inconspicuous things as tiny fossils. Only a handful of scientists are doing this work, and it’s not well-supported—some of our palaeontologists have had to move to Australia to get funding. It’s taken years for conservation workers to incorporate fossil evidence into decisions about which species should be translocated where. But it’s important that institutions like museums keep doing it: a large part of the prehistory of New Zealand is a story told by little bones.


Dr Mike Dickison is the Curator of Natural History at the Whanganui Regional Museum.

Time Travel…

Tooth of the Carcharodon megolodon, a giant shark, over 1 million years. Found near Pipiriki

Tooth of the Carcharodon megolodon, a giant shark, over 1 million years. Found near Pipiriki

An assignment with the geology collection in the Whanganui Regional Museum has given local teacher Keith Beautrais a walk through time that goes back even beyond the formation of our planet.

The Mokoia Meteorite, dated at over 4.5 billion years

The Mokoia Meteorite, dated at over 4.5 billion years

Ichthyosaur teeth from the Mesozoic period 252-66 million years

Ichthyosaur teeth from the Mesozoic period 252-66 million years

“This has already been a mind-expanding experience; to work with an amazing collection, and with scientists engaged in cutting-edge research”, Keith commented.



As part of a science-teacher fellowship run by the Royal Society of New Zealand the Wanganui Intermediate specialist has been sorting through the Museum’s collection of rocks and fossils, discovering just how much material there is.

Three lumbar vertebrae of a Dolphin, likely over 3.5 million years

Three lumbar vertebrae of a Dolphin, likely over 3.5 million years

Ammonite, relative of the Nautilus

Ammonite, relative of the Nautilus

Some of the specimens are 100-year-old rock samples acquired as teaching tools. Others are local fossils collected by palaeontologists or amateur rock hounds. Some have data on where and when they were collected, and most importantly, which rock stratum they came from; others have no label at all and will take some detective work to identify. Keith will be helping to register, photograph and rehouse the very best of our specimens in archival boxes while he is at the Musuem and will, no doubt, uncover some overlooked treasures too.

Phialopecten triphooki, ancestor of the scallop, 3 million years

Phialopecten triphooki, ancestor of the scallop, 3 million years

Because the Museum was without a curator of natural history for many decades, it has relied on sharp-eyed members of the public for specimens. If someone finds an interesting fossil, it is important to note down not just the time and place, but its exact location, even getting the latitude and longitude from Google Maps, including where exactly on the cliff face or stream bed it was found. A photo or sketch can also help. In 50 years’ time, after all, someone might want to find the exact spot and look for more. The all-important label needs to go in a plastic bag with the fossil; if they become separated, the specimen loses all its data and most of its value to researchers.

Teeth of a Pilot Whale, from Kakatahi

Teeth of a Pilot Whale, from Kakatahi

Well over a century of collection and donation has amassed a geology collection that can help young and old appreciate the deep time in evidence around us. Geologists call most of our local fossils “young” because three million years is only 5% of the time since dinosaurs died out. One thing these silent witnesses to our turbulent past remind us of is that, from the perspective of a million years ago, our daily priorities seem very short-term.

Dolphin skull from the Pliocene 5-2.5 million years, collected near Hawera

Dolphin skull from the Pliocene 5-2.5 million years, collected near Hawera

Mike Dickison, Curator of Natural History

With help from Keith Beautrais