“One of the key things that triggered our interest in the fossil when we first saw it was the difference in texture between it and our usual finds,” Mr Shaw said.
“We photographed it and left it on the side of the creek above the flood shear zone. It took all three of us to move it as it was in a large rock that weighed about 70kg.”
Mr Shaw sent the photos to John Simes, emeritus curator at GNS Science and his colleague, National Paleontological Collection manager Marianna Terezow.
“They saw immediately that this was something that needed closer inspection, so back to the site I went with a large battery-powered grinder,” Mr Shaw said.
“I cut the fossil out of the rock and lugged it up the hill so we could crate it up and get it down to John and Marianna in Lower Hutt.”
Mr Simes and Ms Terezow, along with GNS Science colleagues Dr Kyle Bland and Henry Gard, studied the physical characteristics of the rock and the texture and shape of the bone. This gave them its most likely age and source as a fossil vertebra from an early Miocene (between the Otaian and the Altonian stages) cetacean.
This is just the second find of a Cenozoic (“recent” life) cetacean fossil in the Mangahouanga Stream area.
In 2010 Mr Simes collected a small piece of rock with several longitudinal bones which turned out be a series of partial bones from a five million-year-old dolphin skull.
These cetacean fossils are now part of the National Paleontological Collection, housed at GNS Science's Avalon site, and are available for research on request.
Ms Terezow says the fossil record is a valuable part of the whakapapa of Aotearoa's biodiversity and is integral for understanding the state of our past, current and future biodiversity.
“Both these Cenozoic finds bring interesting new layers and value to the story of the Mangahouanga Valley, adding to its already-rich paleontological history,” she said. The Forest Lifeforce Restoration Trust's property at Maungataniwha is of national importance geologically as the site where renowned New Zealand palaeontologist Joan Wiffen first discovered evidence of dinosaur fossils in New Zealand. These fossil remains were extracted from cretaceous rock taken from the Mangahouanga Stream, which joins the Te Hoe River and has the bulk of its catchment within this forest. The Mangahouanga Valley is famous among New Zealand geologists for its extensive late Cretaceous sandstone unit, yielding Aotearoa's plethora of fossil marine reptiles and dinosaurs.
“If any one place is the epicentre of New Zealand paleontology Maungataniwha, and particularly the Mangahouanga Stream, is probably it,” Mr Shaw said. GNS Science has a long-standing relationship with the Forest Lifeforce Restoration Trust. Over the past decade its palaeontologists have worked closely with the trust and Mr Shaw, who leads several conservation initiatives in the area on behalf of the trust.
GNS advice for any intrepid sleuths wanting to head off to the forest to hunt for fossils:
Take with you
■ Suitable outdoor clothing and footwear, e.g. wet-weather jacket, hat, sunnies and suncream.
■ Map, compass (or GPS), notebook and pencil, for recording locations of your finds.
■ Newspaper, plastic bags and labels will allow you to pack your fossil finds and record your collecting locations.
■ A camera. Include an object such as a coin, lens cap or hammer to show the scale in your photos.
■ If you take a hammer and chisel, or a proper geologist's hammer, also take protective glasses.
Safety first
Even the best fossil discoveries are not worth the risk to personal safety! Use common sense to avoid accidents.
Will someone know where you are going, or how long you will be there?
Unstable cliffs and steep ground: Be aware of others around or below you. The rock may give way, especially after rainfall.
Beware of tides and river crossings — water level can change quickly, sometimes resulting in flash floods. Also, check the weather forecast before going and be aware of changeable weather conditions.
Take it or leave it?
The general rule of fossil collecting is don't take it; but if you must take a fossil with you, try collecting from loose boulders where possible. It might be best to leave fragile fossils behind, if removing them might damage them. Take a photo instead.
Keep fossil collecting to a minimum — leave something for others to find.
Before removing any fossils from a site, always check that you have permission from the landowner to do so. Some fossil sites fall on protected land, such as reserves. Collecting from these areas is forbidden, but this should not deter you from enjoying these places and taking many photographs of the treasures you come across.
A significant find?
Many fossils of scientific importance have been discovered by amateurs.
If you think you have found a potentially significant specimen, such as a fossil bone, tooth or other well preserved plant or animal material, contact GNS Science, your local university geology department, or museum to have an expert check it out.
You will particularly impress the scientists if you have written down the exact location of your find! Sending an email with a photo of your specimen is a good way to make initial contact.
