Fossil hunters scouring the streams of one of this country’s palaeontology hotspots have found rare evidence of an ancient marine mammal. The find, most likely a vertebra from a small whale, is somewhere between 16 and 19 million years old and experts from GNS Science say it adds to the picture of New Zealand’s past biodiversity.
The vertebra fossil was found in Mangahouanga Stream in the Maungataniwha Native Forest in northern Hawkes Bay. It was discovered by Wellington-based Brent Beaven, a senior manager with the Department of Conservation, who was on a hunting trip with businessman and conservationist Ed Chignell and Pete Shaw, forest manager of the Forest Lifeforce Restoration Trust.
Mr Shaw is an experienced fossil hunter. In 2019 he was awarded the Harold Wellman Prize by the Geoscience Society of New Zealand for his work on fossils in the Maungataniwha Native Forest. But it was only the second time Mr Beaven had looked for fossils.
Mr Beaven found the fossil in a section of the Mangahouanga that has yielded finds in the past. The team had reached a tight gorge and were just about to wrap up their search.
“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 upon 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 palaeontology 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.