Day: July 10, 2019

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.