Life After Death
Even in extinction, the Tasmanian tiger moves in mysterious ways – hiding in plain sight, duping students and experts, revealing its true nature in slow motion, writes Ivy Shih.
We know more about how the thylacine died than how it lived. The Tasmanian Tiger seems to haunt the periphery of our collective consciousness. It lives on, ironically, as an icon of extinction. The story of its extinction is a tragic tapestry of forces beyond the animal’s control – a combination of a changing climate, shrinking habitats and human competition.
The thylacine (thylacinus cynocephalus) is the largest carnivorous marsupial to exist into modern times. Around 3000 years ago, thylacines disappeared from the Australian mainland, leaving a small population in the island state of Tasmania. It was a strange-looking animal with an elongated dog-like snout, long-legged gait, striped lower back and backward-facing pouch. It was known by many different names to Indigenous peoples, including corinna and kanunnah, and English-speakers gave it various names too, over the years, including ‘marsupial wolf’, ‘pouched wolf’ and, of course, ‘Tasmanian tiger’. But the moniker bestowed by Tasmanian graziers, ‘sheep-killer’, became the catalyst for its extinction. In the late 1800s, the Tasmanian Government introduced a bounty on thylacines to help protect livestock. The bounty is believed to have accelerated the demise of the species. Records show that bounties were collected from the Tasmanian Government on 2184 animals between 1888 and 1909, though it’s believed private landowners offered bounties and paid them, too.
When the last known animal in captivity, ‘Benjamin’, died in Hobart’s Beaumaris Zoo on 7 September, 1936, the ecological gravity of its passing was largely ignored. Today, the creature is famous for being extinct. The anniversary of Benjamin’s death is now National Threatened Species Day in Australia.
What we know of the thylacine’s life cycle and behaviour is patchy. Thylacines were never systematically studied in the wild by naturalists, save for photographs and jerky footage of animals in captivity. There are conflicting witness accounts of how they moved and what they ate. For tangible information on the thylacine, we have to look to historical artefacts. The thylacine’s likeness has been drawn in scientific illustrations and their bodies have been quartered for trophies and specimens.
The combination of old specimens and new technologies has cleared the thylacine’s name as a livestock-killer.
These specimens are spread across the globe. What remains, at least officially, of the thylacine are about 800 wet and dry thylacine specimens that now rest in 116 museums and public institutions in 23 countries, with 137 specimens in Tasmania alone. The International Thylacine Specimen Database is a living document that lists all publicly known thylacine specimens.
Catalogued items include pelts, scattered bones, complete skeletons and the carcasses of thylacine adults and pouch alike – either preserved by taxidermy or suspended in preservative fluid. Perhaps the most striking items in the database are the 98 internal thylacine organs, one of which is a dried thylacine stomach in Cambridge, resembling brittle grey plastic.
Marsupial in wolf’s clothing
Credible new thylacine sightings are still happening, but they’re happening within the archives of museums and laboratories. For conservators and zoologists, these findings can generate almost as much excitement as if they were sightings of living thylacines in the wilds of Tasmania or Queensland. Melbourne-based zoologist Rohan Long had one such sighting in September last year, chancing upon a stray specimen at the University of Melbourne’s biology department. At the time, Long was collections manager at the university’s zoological Tiegs Museum, meaning he kept constant company with specimens dating back to the 19th Century.
On an ordinary day, while walking through the biology labs in a separate part of the campus, Long spotted a cluster of bones that caught his eye. The bones were laid out on a tray, and from the layout, Rohan could see the bones were on standby to be used in an upcoming practical class. The bones were dog mandibles – also known as jawbones and skulls – ready for first-year students to inspect in a lesson about the difference between herbivore and carnivore teeth.
But one particular specimen caught Rohan’s eye and he decided to look into the matter a bit further. Some of the specimens had rows of numbers inked along their sides, a common cataloguing practice among curators to ensure skull and jawbone pairs are not separated. Rohan took a few photos on his phone, made some notes and moved on.
‘I thought, “Why not write those numbers down and run them through the catalogue to see if they were specimens taken from the zoology museum,’” he says. The Tiegs Museum is Australia’s oldest university museum of zoology. During its 120-year lifespan of collecting, it was inevitable that specimens stray into other departments.
During his search, Long found that canine jaw number 1564 had a surprising origin.
He checked, double-checked and triple-checked the numbers. ‘Oh god,’ he recalls thinking. ‘1564 is a thylacine skull.’
Number 1564 was the missing part of a thylacine skull that had entered the museum’s collection in the 1920s. Though the thylacine’s snout is thinner than a dog’s, Long explains, it is difficult at a glance to see the difference between dog and thylacine skulls.
It lives on, ironically, as an icon of extinction.
It’s unknown how the cranium and mandible of 1564 were separated, but staff in the university’s biology department believe the specimen had been mixed up with dog bones for at least 20 years. For decades, students had been unaware that the ‘dog jawbone’ in their hands was the jaw of the national symbol of extinction. Back at the Tiegs Museum, Long placed the mandible with the corresponding cranium, which was on public display.
‘The two pieces fit perfectly together,’ Long says. ‘There was no doubt.’
Skull and jaw united, Long’s next move was to contact the International Thylacine Specimen Database, to add his rediscovery to the catalogue.
‘For anyone in a natural history or zoology profession, [thylacines] have such an iconic presence and occupy a really precious space for people,’ says Long. ‘In terms of the collection, you’re not going to be adding more thylacine material. Everyone is conscious of that fact.’
Secrets of evolution
Thylacine specimens are especially valuable, too, because scientists believe the species might hold the answers to questions we’re still asking about evolution. Locked within thylacines’ bodies are valuable historical archives of scientific value. New technology means we can learn even more from preserved specimens.
The thylacine is viewed as one of the best examples of convergent evolution in mammals. This is the process by which two species, despite not being closely related, evolve to look very similar by adapting to similar environments or ecological niches. Despite having dog-like features like the dingo, the Tasmanian tiger last shared a common ancestor with the canids (dogs and wolves) around 160 million years ago.
The combination of old specimens and new technologies has cleared the thylacine’s name as a livestock-killer, too. Digital 3D models created using computed tomography (CT) scans of thylacine skulls allowed scientists in 2011 to test whether it was possible for thylacines to kill certain types of prey. University of New South Wales scientists tested the thylacine’s capacity to perform common killing behaviours such as shaking, pulling and biting down using simulations. Thylacines were found to have weak jaws, unable to produce the force needed to take down large animals. Instead they were more suited to catching small-sized prey, such as bandicoots and possums.
Locked within thylacines’ bodies are valuable historical archives of scientific value.
For Christy Hipsley, a vertebrate palaeontologist from Museum Victoria, the thylacine is a species that continues to astound.
‘Humans lived with it … not just for a short time, but for thousands of years, yet we know so little about how it lived,’ she says.
Hipsley has had two close encounters with the animal. She was part of the research team last year that sequenced the genome of a one-month old thylacine pup, which means we now have an entire thylacine DNA blueprint.
In a more recent project, the team used the International Thylacine Specimen Database to track down every known preserved thylacine pouch young. There were 13 specimens in total, all preserved in ethanol – from less than two weeks old to 12 weeks old. Using CT scans, they created digital models, enabling them to gain a clearer picture of the development of thylacine joeys.
The CT scans of the specimens revealed another example of misclassification of this elusive species. Two specimens from the database were found not to be thylacine young at all, but rather quolls or Tasmanian devils. This was uncovered based on the number of vertebrae, and the presence of large epipubic bones (specialised bones that support the pouch in modern marsupials) found.
Meanwhile, the digital scans of the real thylacines show in incredible detail how they started life as joeys looking very much like any other marsupial, with robust forearms so they could climb into their mothers’ pouches. But by the time joeys left the pouch at around 12 weeks to start independent life, they looked more like dogs or wolves – with longer hind limbs than forelimbs, and a predator’s jaw.
‘What we are doing is to take this old material which is static – and we expose those old specimens to new technologies to reconstruct how the animal lived,’ Hipsley says.
Strays, skulls, sightings
The emotional connection between museum curators and the collections under their care is palpable, especially in an era when new technologies are increasing the value of older specimens.
For decades, students had been unaware that the ‘dog jawbone’ in their hands was the jaw of the national symbol of extinction.
‘I felt a real responsibility as … caretaker of this collection,’ Long says. ‘This ancient, hundred-year old collection that doesn’t receive as much love as it once did … The value of natural history collections is that the museum and its staff catalogue, host, and curate to keep our history safe and [to ensure] we have information available for the future.’
Long now works as curator at the Harry Brookes Allen Museum of Anatomy and Pathology in Melbourne. These days, he’s looking after items from a very different branch of the phylogenetic tree; the museum holds specimens of human tissue and historical anatomical human models.
But when he first began working there in March 2018, one of the first things he noticed was a museum display that stood out from the rest of the specimens. Among preserved examples of human diseases and detailed models of anatomy fashioned from wax and plaster, there was one display with animal remains dating back to the 1930s.
The display took the form of a wooden board with various animal skulls attached. Its purpose was to show examples of convergent evolution for anatomists to study when comparing human and animal anatomy. One of the skulls was that of a dog. Next to it was a skull of a thylacine. For the second time in six months, Long contacted the International Thylacine Specimen Database to tell them that a new entry needed to be made.
How many other thylacines parts are lurking, unclassified, in the vast natural history collections of our museums and institutions, or hiding in plain sight, or masquerading as other species? Officially extinct for more than 30 years, the thylacine continues to play tricks on all of us – even those who work with the species at close quarters.
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