International scientists look for two-million-year-old fossils in Whanganui

The team of international scientists at Castlecliff Beach. Photo / Bevan Conley

A team of international scientists are in Whanganui this week to unearth unique fossils along the coastline.

Since 2014, the group has travelled to Whanganui four times to collect samples of bryozoa - tiny animals growing on shells - to send overseas for further examination in laboratories.

University of Oslo Natural History Museum evolutionary biologist/palaeontologist Lee Hsiang Liow said the cliffs between Castlecliff Beach and Kai Iwi contained a fantastic fossil record.

“An analogy is that if you’re looking at records somewhere else, it’s like you’re reading the first page and last page then trying to work out what’s happened in between - but here you’ve got the whole book.”

An example of bryozoa as seen under a microscope.

Liow said the fossils revealed evolutionary processes.

“We have these little critters fighting each other for space, and we actually can see that as fossilised activity.”

New Zealand palaeontologist Seabourne Rust said they had found new species of different animals in the cliffs, and some were known only from this area: “That’s pretty exciting.”

A lot of the shell fossils being collected can fit in the palm of a person’s hand.

Rust said layers of ash from volcanoes in the central North Island, such as Taranaki and Taupō, covered this area at a number of key points in time, which made it easier to date the fossils.

National Institute of Water and Atmospheric Research (Niwa) bryozoologist Dennis Gordon said people most commonly encountered bryozoa fouling on the bottom of vessels, but some of these fossils were more than two million years old.

The fact they lived in a colony, like coral, was very important, he said.

“The fact that they’re colonial and modular means you get combinations of different characters that can be measured more than you can in a single organism like a snail.”

He said bryozoa could be found everywhere in New Zealand, in places such as the Waitomo Caves and the Chatham Islands.

Liow said because the cliffs were made up of fossils that would break off and fall into the ocean, the information would just disappear unless it was recorded.

“It’s tiring to travel across the world to do this, but because it’s so great, we just have to come back here all the time.”

Rust said they had observed sea level changes that corresponded to glaciation throughout the last three million years.

Some of their research could be used to examine the impact of sea level changes over time and to explore what animals might disappear or move into areas as a result.

“The past is really key to the future, in a way.”

Oslo Natural History Museum’s Meghan Balk said people admiring the beach might not have realised that they could see fossils when looking back at the cliffs.

“You’re looking through time as you look at the cliffs.”

To collect the fossils, the group uses brushes, pen knives and occasionally hammers and chisels to excavate the soft rock of the cliffs.

Rust said the cliffs were very steep and dangerous and members of the public should be careful when looking for fossils.

It was also important to record exactly where a fossil was found, either by marking down its co-ordinates on a map or taking a photograph.

Eva de Jong is a reporter for the Whanganui Chronicle covering health stories and general news. She began as a reporter in 2023.