New approaches to old collections

Ask someone to imagine a museum’s natural history collection and they will likely think of dark Edwardian halls. Inside these long shaded corridors are endless cupboards stuffed with a vast menagerie of natural treasures from the past, locked away for safe-keeping.

In a very small part, this description depiction is true; natural history collections are dimly lit to protect valuable specimens from light damage and they are vast libraries of the natural world, enabling us to make sense of biodiversity.

However, there is one major misconception to this concept: these collections are most definitely not locked away in the past. Auckland Museum’s valuable libraries of past life are regularly brought out by researchers to answer a diverse range of future-faced research questions. They are effectively walking into the future facing backwards - “ka mua, ka muri”.

In our rapidly-changing world, new technologies are increasingly being deployed to draw meaning from “old” collections, be it thanks to the revolution of molecular and cellular techniques such as radio carbon dating, stable isotope analyses or ancient DNA, or the use of new software that allow data to be collected from specimens in ways we could have only dreamed about a decade ago.

As Curator of Land Vertebrates at Auckland Museum it is my privilege, along with our Collection Manager, Ruby Moore, to support a range of talented researchers in accessing our collections with toolkits of scanners, probes and multi-spectrum cameras. I thought what better exercise in lockdown than to harass the most recent cohort to tell you about the work they have been doing amongst the collection’s 23,000 specimens.

 

_{Background image: Matt helping staff to identify feathers in cloaks at a workshop in 2018. Photo by Jenn Carol.}

A new approach to bone ID

As part of her Master of Science (supervised by Dr Daniel Thomas) at Massey University, Emma Holvast sought to find a new way to identify bones. She used three-dimensional scanning technology and bird bones from the land vertebrate collection.

Have you ever happened upon a bone while at the beach and wondered what animal it might be from? My Master of Science research explored a method to answer questions like this.

Using three-dimensional (3D) scanning technology, my research aimed to provide taxonomists, scientists who specialise in describing species, with a new way of collecting a multitude of different measurements from bones. In particular, I focused on a diverse group of seabirds called tubenoses. This group includes albatrosses, petrels, shearwaters, prions and tiny storm petrels - whose bones are incredibly hard to measure by hand. These seabirds are a great study system for this research as New Zealand is the global centre of seabird diversity. As a result, local museums, and especially Auckland Museum, contain an abundance of their bones.

To carry out my study, I created a library of 3D digital models from different seabird bones in the Museum’s collections. My library grew to contain over 400 digitised bones over the course of my project. Building this collection involved 3D scanning bones with a handheld 3D laser surface scanner, a tool I brought with me to the Museum. I then used 3D shape information from the digitised bones to develop a statistical classification method which allowed me to accurately identify the family that a bird belongs to.

Working with Auckland Museum has been a fantastic opportunity to meet the Natural Sciences team and undertake collections-based research, which I am passionate about. One thing in particular that struck me while working in the seabird collections was the sheer size of the bones of some of the larger tubenosed bird species. While I was aware of the large wingspans of the albatrosses, viewing the wing bones of these birds up close and handling the specimens, such as those belonging to New Zealand endemic toroa, was truly astonishing.

I was also fortunate to be able to borrow specimens belonging to species within the southern storm petrel family Oceanitidae for micro-CT imaging as these bones were too small to be digitised effectively using our surface scanning equipment. Multiple small bones were imaged at once using a specially designed specimen holder placed inside a micro-CT instrument. This meant that I could cover the full-size range of tubenosed bird specimens and produce a more inclusive dataset for my study.

I am very grateful to Auckland Museum for the privilege of working in the land vertebrate collections and the use of their seabird specimens for my research.

 

_{Background image: Halobaena caerulea (Blue Petrel); LB261 © Auckland Museum CC BY}

Unlocking the secret of bird flight

For their final-year mechanical engineering project (supervised by Dr Michael MacDonald), University of Auckland students Richard Norris and Ben Peterson aimed to better understand how gliding birds soar to assist in designing unmanned aerial vehicles.

They used bird wings from the land vertebrates collection alongside three-dimensional scanning technology and advanced computational fluid dynamics software.

Gliding birds, such as petrels and albatrosses, are common around New Zealand’s coastlines and seas. Over millions of years, these birds have developed amazing aerodynamic abilities; with little effort, gliding birds can travel thousands of kilometres across open oceans. The ability of these birds to soar and remain in the air for long periods of time, without flapping their wings, has fascinated humans for centuries drove the development of our own winged vehicles in pursuit of flight.

For our final-year mechanical engineering project, we sought to use birds’ wings held in the land vertebrates collections at Auckland Museum to improve the design efficiency of fixed-wing unmanned aerial vehicles (UAVs). Although developed originally for military purposes, there has been an explosion in the design of smaller prototype UAVs for a variety of uses, including search and rescue and delivering medicine to remote areas.

We conducted high resolution 3D scans of the extended wings from Northern giant petrel (Macronectes halli) and Salvin’s mollymawk (Thalassarche salvini), to obtain a precise model of the wing shape. Model wings were then 3D printed and tested in a specialised wind tunnel, and simulated using advanced computational fluid dynamics (CFD) software. This enables someone to see in exceptional detail how the air flows around the wings and therefore analyse the aerodynamic performance.

The aerodynamic performance of bird wings is useful to engineers designing fixed-wing UAVs. These UAVs are increasingly being used for tasks like medicine delivery to remote areas and in search and rescue operations. Much of our engineering aerodynamic knowledge is based on relatively large and fast aircraft designed to carry humans. This knowledge does not necessarily apply to smaller fixed-wing UAVs. It is hoped that the insights from bird flight could inspire the future design of efficient UAVs, which would burn less fuel and stay airborne for longer.

Understanding the aerodynamic behaviour is also useful for zoologists and conservationists to predict energy expenditure for these often endangered birds. This could help with predicting their migratory flight paths and range, as well as giving insights into their metabolism.

 

_{Background image: Thalassarche salvini (Salvin’s Albatross); LB1892 © Auckland Museum CC BY}

Uncovering hidden diversity in New Zealand’s large geckos

As part of his University of Otago Master of Science (supervised by Dr Nic Rawlence), Lachlan Scarsbrook used micro-CT scanning and gecko bones to offer insight into whether Aotearoa has undiscovered species of extinct large geckos.

While we often hear about our birds, Aotearoa New Zealand is also home to the most diverse group of lizards of temperate regions in the world, comprising over 104 species of geckos and skinks. These two groups have radiated into almost every available role in the New Zealand ecosystem; from the intertidal foraging Suter’s skink to the alpine-adapted orange-spotted geckos, our lizards have evolved some very interesting quirks indeed. Duvaucel’s gecko is no exception, being both viviparous (gives birth to live young) and living to over 50 years old. This giant among geckos is most famous for being New Zealand’s largest living lizard, reaching up to 30cm in length!

Paleontologists have previously used the large size of Duvaucel’s gecko bones to identify prehistoric subfossil gecko bones, most of which have been found across the country in rockshelter roosts of the extinct laughing owl, which loved to eat lizards. While this use of size can be informative, Aotearoa’s lizard fauna has been poorly studied, so there has likely been cryptic extinctions; where the loss of species that are morphologically near-identical is invisible in the fossil and archaeological record. To further add to the problem, the modern distribution of Duvaucel’s gecko is restricted to a small number of offshore islands, where they have survived the ravages of introduced predators that wiped out their kin on the mainland. This means that scientists may have oversimplified the diversity of large, Duvaucel-sized, geckos in New Zealand prior to human arrival by lumping multiple distinct species together. To discover whether we’ve missed anything, I’m tackling this problem with the 21st Century science of micro-CT scanning (a scaled down version of a common hospital CT scanner, but for small things) and ancient DNA.

Gecko skulls are made up of a number of small, unfused bones, which unsurprisingly fall apart and become fragmented after passing through a laughing owl’s digestive system, making complete prehistoric skulls almost rare as hens’ teeth. As a result, my micro-CT scanning focused on one, common cranial element found in museum collections around Aotearoa: the maxilla or upper jaw bone. I also used representatives from most living New Zealand geckos to determine whether the prehistoric subfossils most closely resembled surviving species or were in fact something different, something new.

Each maxilla was micro-CT scanned to generate a 3-dimensional model for comparing how their shape differed across different gecko species. Using statistical models, I was then able to decipher what these miniature Rosetta Stones were trying to tell me. Some prehistoric subfossil maxilla grouped with living species like Duvaucel’s gecko (as we expected some of them would); Amazingly, other maxilla showed no strong association to any living New Zealand gecko. These morphologically unique jaw bones, previously thought to belong to Duvaucel’s gecko, likely represent an undiscovered species of extinct large geckos that once called Aotearoa home.

However, before we can seal the deal on a new species of gecko, we need to do some genetic time travel and extract ancient DNA from these precious prehistoric subfossils to reconstruct their whakapapa. Good things take time, so stay tuned.

 

_{Background image: Micro-CT scanned surface model of Duvaucel’s gecko skull showing a range of views and locations of measurements for taxonomic characteristics. Image supplied by Lachlan Scarsbrook.}