Research website of Dr Gilbert Price

Tall Poppy Awards

One of the things that I really enjoy about my work is telling people about it! I mean, who doesn’t love a good yarn about an Ice Age cold case featuring some of the coolest, biggest and meanest beasts that ever walked the planet! It’s an easy sell too- most people know a little about dinosaurs, but when you tell them that there were giant wombats, massive kangaroos, and marsupial lions living alongside Australia’s earliest peoples… well, their jaws just drop!

I was recently invited to attend the awards ceremony of the Queensland Young Tall Poppies. The awards are an initiative of the Australian Institute of Policy and Science, or AIPS. Each year, AIPS celebrates and recognises the achievements of young scientists across Australia as part of their Tall Poppy Campaign. Their ultimate aim is to strive towards the building of more engaged scientific leadership across Australia, and that by necessity, means scientific communication, not just between scientists, but with the general public alike.

Tall Poppy Awards

Discussing my research at the 2013 Queensland Tall Poppy Awards (it’s not often that you’ll find me this clean and wearing a suit!)

The awards are made on a state-by-state basis and recognise the achievements of outstanding young researchers across a huge variety of scientific fields including medical research, technology, engineering and mathematics. I’m pleased to say that my name was among the list of 11 awardees for the 2013 Queensland Young Tall Poppies. It was a real thrill and surprise for me. The award ceremony was held at the Queensland University of Technology’s Science and Engineering Centre in mid-November (a really impressive place that you should check out next time you are in Brisbane City!), hosted by Queensland’s Chief Scientist, Dr Geoff Garrett, with the individual awards presented by the Queensland Minister for Science, Information Technology, Innovation and the Arts, Mr Ian Walker.

Out of the 11 awardees, one was chosen to become the Young Queensland Tall Poppy of the Year. The 2013 candidates are an incredible bunch of young scientists and include researchers working in a variety of different areas from molecular biology, public health, neuropharmacology, tissue engineering and more. I was really blown away to hear about their research- they’re doing some massively impressive things. But what surprised, and humbled me more than anything, was when I heard my name read out for the top prize! I really couldn’t believe it!

My boss, Professor Gregg Webb, was in the audience- he was super pumped, perhaps even more than I was! It’s a great opportunity, not just for me, but for my research group to really start showing off some of the cool palaeo-type things that we do. Although I tend to talk up my megafauna research much more than anything, the real crux of what I do really goes far beyond those Ice Age megabeasts. Yep, it would be awesome if we could figure out why diprotodon and co suffered extinction, but wouldn’t it be brilliant to know how the species that we still have around us today staved off extinction? How did they respond to the massive climatic changes and anthropogenic impacts that have gripped Australia since the last Ice Age? How were they able to adapt at a time when a huge variety of different creatures were dropping off the evolutionary family tree?

Receiving the 2013 Tall Poppy Award

Receiving the 2013 Tall Poppy Award from the Honorable Mr Ian Walker

So that is the ultimate research question- how have modern floras, faunas and ecosystems responded to past episodes of climate change and environmental peturbation? And critically, what can we do with that knowledge? The past is what informs that present, and it can also help us understand where we might be heading in the future. That’s an insight that can only be provided by the fossil record and is especially important at this time of widespread apprehension over the potentially devastating impacts of future anthropogenic climate change. There are a lot of lessons that we can learn about the past, with great potential for applying that to modern conservation approaches and ecosystem management.

I’m looking forward to the opportunities that the Young Tall Poppy award will bring me over 2014. It’ll be a great chance to spread the fossil-word to one and all, and hopefully attract a bit more community support for the palaeo-sciences, not just in Queensland, but across Australia more broadly.

Keeping your hands clean in the field

Euryzygoma premaxilla fossil from Chinchilla showing three incisor teeth

Euryzygoma premaxilla fossil from Chinchilla showing three incisor teeth

The life of a palaeontologist isn’t all that glamorous. Most of my time is spent in the office in front of a computer writing reports and grant proposals. One of the things that I really look forward to is getting out in the field and getting my hands dirty. There is nothing quite like being outside in the fresh air and digging up fossils.

I recently ventured out to Chinchilla, southeast Queensland, in search of Pliocene megafauna. I’ve written previously about Chinchilla’s fossil record; in a nutshell, the fossil faunas date to around 3.5 million years and include all the ancient ancestors of the animals of the Quaternary (the time period that we are currently in). Significant amongst the Chinchilla fossil species is a mega-marsupial, the wombat-like Euryzygoma. Not only was it the biggest marsupial of its time, but it probably ranks as number 2 or 3 of all time! Euryzygoma is a real special guy- not only is it the direct ancestor of the Pleistocene Diprotodon, but it is unique in that it is one of the only mammals known on the entire planet that had a skull that it is wider than it is long! This is made possible by it possessing these incredible cheek flanges that are directed outwardly perpendicular to the rest of the skull.

Students protecting the Euryzygoma fossil with wet newspaper

Students protecting the Euryzygoma fossil with wet newspaper

During our time in Chinchilla, I stumbled across a pretty interesting looking Euryzygoma specimen eroding from an ancient river channel. The fossil, although broken, included the front part of the premaxilla (‘snout’) and contained three incisor teeth. It’s definitely a specimen that will contribute significantly to understanding more about how Euryzygoma operated in life.

We were lucky to have several guests join us during our trip- grade 10 students from the Samford Valley Steiner School. They were worked alongside us, not so much on the palaeontology side of things, but were focussed on surveying the region and drafting topographic maps. The maps will be just so important and will allow us to plot in exactly where the fossils come from.

Students cutting up the hessian in anticipation for plastering the fossil

Students cutting up the hessian in anticipation for plastering the fossil

Even though this is one of my favourite bits of doing fieldwork, I spoke to my other colleagues on the trip and we all agreed that it would be a great chance for the students to get their hands dirty and help excavate the new fossil… and they did a tremendous job! Because it is such a delicate specimen, it was necessary that we just didn’t dig the fossil out and throw it in a bag, but rather, we needed to plaster the fossil in a similar way as if you broke your leg. The first step was to dig around the fossil, making sure that we knew where the extremities of the specimen were (only a little part of it was actually exposed), and to ensure that there was enough area for the plastering work. The students then soaked sheets of newspaper and wrapped them around the fossil. There are a couple of reasons for doing this- firstly it will cushion the specimen once the jacket is finally removed; and secondly, it protects the specimen from the plaster (plaster is notoriously sticky stuff and could actually wreck the specimen if it is applied to it directly).

Steiner School students plastering the Euryzygoma fossil

Steiner School students plastering the Euryzygoma fossil

While some of the students did this part, others busily cut up strips of hessian and mixed the plaster. Then it was time to get messy! The students soaked the hessian strips in the plaster and then wrapped them around the specimen. The idea is that the hessian reinforces the plaster much like steel reinforces concrete. When the plaster eventually dried, we had a super strong cast around the specimen. We left it for a few hours to harden and then we dug under it, rolled it over, and it was ready to go. Because the students undertook the entire task, I didn’t have to get my hands dirty at all! I think that they got a lot out of it- I mean, it’s not every day that one gets to make a plaster jacket for a fossil of an extinct mega-marsupial!

The specimen travelled back with us to The University of Queensland and is now ready for additional preparation work. Although, I was thinking about it the other day- this might be another great opportunity for kids to do the prep job at an upcoming Open Day at UQ. At this rate, I might not have to clean out dirt from under my fingernails ever again!

Ice Age Queensland

In late 2011, I was invited to write a chapter for an upcoming book on the Quaternary geology of Queensland. Not being a geologist, I was initially hesitant to take on the job. I thought about it for a bit though- I work in the Quaternary (i.e, the last 2.6 million years of Earth’s history) and in Queensland, so I eventually thought to myself, “why not?!” It turns out that it was one of the most challenging things that I have ever done, but also one of the best moves that I could have made.

Ice Age Queensland

Quaternary chapter for ‘Geology of Queensland’ (2013; ed. Dr Peter Jell)

Over the course of a month or so, I read a huge number of papers. I already knew the palaeontology side of Queensland’s Quaternary pretty well so that was not a big problem, but I also had to had to get stuck into loads of papers on palaeoclimates, fluvial and aeolian deposits, speleogenesis, soil formation and weathering, and volcanism- the sorts of things that aren’t normally on my reading list. But I learnt so much.

What really struck me was that although Queensland doesn’t have too much going in the way of Quaternary economic geology, most research had a strong palaeoclimate / palaeoenvironmental theme. And what really stood out was the role of geochronology (dating) in tying all of these seemingly disparate records of Queensland’s Quaternary together. Back in the early 1960’s, the time of the first modern review of Queensland geology, there were very few methods with which to date the important deposits. However, since then numerous geochronological approaches have been developed that allow for the development of a reliable temporal framework critical for understanding how climate change has impacted upon and shaped Queensland over the past 2.6 million years.

The modern Channel Country of western Queensland in flood (photo: G. Nanson)

The modern Channel Country of western Queensland in flood (photo: G. Nanson)

By combining all of the results of the different studies, it immediately became clear that there have been some massive climate-driven environmental changes in Queensland, and more broadly through Australia, over the course of the Quaternary. The first part of the Quaternary was relatively warm and humid, and less seasonal than it is today. Up until around 300 thousand years ago, conditions were so good that extensive rainforests grew much of the way along the eastern coast. The arid interior was not even that arid at that time. In fact, it was fairly well-watered, possibly with semi-permanent La Niña conditions in place for several thousands of years (incidentally, the La Niña climate systen is what caused the terrible flooding of 2011-13 in eastern Australia; but it was even wetter 300 thousand years ago!).

After around 300 thousand years ago, long before the first humans traipsed onto Australia’s shores, the climate started to shift, so much so that the rainforests of the east started to contract northwards; the arid inland rivers began to dry up; and numerous species started disappearing from their formally well-watered environments.

Late Quaternary stalagmite that grew from 20-7.8 thousand years ago

Late Quaternary stalagmite that grew from 20-7.8 thousand years ago

The results showed that long-term shifts in climate oscillation, in line with orbital forcing, saw Queensland descend into an intense last glacial cycle or ‘Ice Age’. The late Pleistocene (beginning around 130 thousand years ago) started with a massive marine transgression of the Gulf of Carpentaria, which coincided with incredible fluvial activity both in north Queensland and the western Channel Country (flowing into Lake Eyre in central Australia). The warm, wet conditions persisted through 120-90 thousand years ago. Temperatures then plummeted, causing sea levels to fall so low that the Gulf of Carpentaria became a lake! The change is also associated with a major vegetational reorganisation in the tropics, with other records suggesting reduced monsoonal activity at that time. Through this period, you can see a progressive decline in megafaunal diversity in southeastern Queensland.

After around 47 thousand years ago, fluvial activity basically ceased in the Channel Country, and dune building became the dominant sedimentological process. This coincided with the time that saw the final ever filling of the Lake Eyre megalakes (the connection of Lake Eyre to other central Australian lakes). There is also the last direct, dated evidence for megafauna at that time (the youngest assemblage that we know about – Neds Gully – had only two or three large-bodied megaherbivores, rather than the 65+ species that are commonly regarded as having being extant at that time). The earliest record of humans in the State is around 40 ka. The intense climatic / biological events were clearly in-train before that.

One of the youngest Diprotodon skulls known (this specimen is from Neds Gully, Darling Downs)

One of the youngest Diprotodon skulls known (this specimen is from Neds Gully, Darling Downs)

The vegetation shifts after 45 ka and up to the Last Glacial Maximum (around 20 ka) were similar to previous changes from earlier glacial maxima in some ways, but was markedly more intense in terms of its aridity. The sedimentological record of Lake Carpentaria from the early penultimate last glacial maximum (just before 130 ka) saw vast rivers flowing across the lake, whereas as the period leading into the Last Glacial Maximum saw the lake transition through phases where there was almost total desiccation. The period around the Last Glacial Maximum also saw significant landscape instability (in part, a function of a change in vegetation cover from forest to open habitat). Post-Ice Age warming meant a return of the monsoon, leading to Lake Carpentaria expand to capacity size and all-time lows in salinity, then full marine transgression by around 10 thousand years ago. Speleothem (e.g., stalagmites) records suggest an enhanced monsoon after that time as well. This is of course all associated with another vegetation shift where forests returned and swallowed up the open areas.

The implications of this synopsis are massive when it comes to trying to understand the causes of megafaunal extinctions. Although it is regularly argued that climate change was not significant in the last glacial cycle and that there was no climate change when the megafauna supposedly went extinct between 40-50 thousand years ago, the data just do not support such an inference. There were incredible changes at that time and were part of a long-term shift towards increasingly arid climates. This doesn’t mean that climate alone caused the final megafaunal extinctions (the earliest humans, arriving around 50 thousand years ago could also have made a contribution), but we can no longer ignore it.

My chapter was published in the book ‘Geology of Queensland’ (edited by Dr Peter Jell) earlier this year. The rest of the book documents all other aspects of what we know about Queensland’s geology, not just the Quaternary. It’s an incredible book- I highly recommend it to one and all. It’s a huge read- over 900 pages, full colour, hardback, and retails at only around $75! Such good value and one of the most important books ever written on any aspect of Australian science. You can order it here.

Summary of major climatic and biological events for the last 350 thousand years in Queensland relative to the oxygen isotope curve

Summary of major climatic and biological events for the last 350 thousand years in Queensland relative to the oxygen isotope curve

Diprotodon’s big day out

The early stages of preparing the Diprotodon skull (photo: I. Sobbe)

The early stages of preparing the Diprotodon skull (photo: I. Sobbe)

I recently wrote about a giant Diprotodon skull that was discovered fossilised in Pleistocene-aged deposits on the Darling Downs. It is a monstrous skull, measuring around 90 cm in length, and discovered by a local simply walking along the creek. With the help of the discoverer, we excavated the skull, then my friend, Ian Sobbe, a local farmer and amateur palaeontologist, set to work preparing the skull.

Ian spent the best part of a year working on the specimen. Simply put, Ian did a cracking job. It’s a wonderfully preserved skull with exquisite detail. Ian used a combination of brushes, dental picks, scrapers, glues and other consolidants to remove the surrounding sediments and ensure that the skull wouldn’t crack and break as it dried out.

The Diprotodon skull nearly finished (photo: I. Sobbe)

The Diprotodon skull nearly finished (photo: I. Sobbe)

With the original discoverer’s blessing, the skull was donated to the Queensland Museum in September 2012. By having the skull in an institution like the Queensland Museum, it ensures that the specimen will be well-looked after and stored in the most appropriate conditions (temperature and humidity controlled storage and so on) to ensure its long-term preservation. The skull will most likely also go on display to the public sometime in the next year or so.

Ian and I have some big plans for the skull. We’d like to eventually write-up a description of the specimen and have it published in a peer-reviewed science journal. We are also working with a PhD student from Monash University, Alana Sharp, who is conducting a study on the nasals of the big guy.

Ian Sobbe and the Diprotodon

Ian Sobbe and the Diprotodon

I have also drilled tiny tooth samples from the skull that will allow me to directly date it using uranium-series methods (currently in preparation). I already have some radiocarbon dates for the skull, and hopefully soon, some optically-stimulated luminescence (OSL) dates by my colleague, Dr Kathryn Fitzsimmons (Max Planck Institute for Evolutionary Anthropology, in Germany). If we can get some really good results- dating, anatomy and biology, it’ll be just so important for learning more about how Diprotodon lived and died.

Digging up Diprotodon

It was around August 2011 that my friend, Ian Sobbe, received a phone call from a local on the Darling Downs: “I’ve found a skull in the dirt- it looks like a Grand Angus bull”, the caller said. Well, Ian, being not only a local farmer from the Downs but also an amateur fossil collector, started to get excited. Knowing a lot about the fossils from the region, Ian checked out the photos that the local had emailed him and immediately called me up. The skull was not a Grand Angus at all, but as Ian correctly identified, it belong to the extinct mega-marsupial, Diprotodon.

The Diprotodon skull was found eroding out of this creek bank

The Diprotodon skull was found eroding out of this creek bank

Diprotodon was a giant among giants- not only the largest marsupial that lived on the Darling Downs during the Pleistocene, but is also the largest marsupial that ever lived… at any time… anywhere on the entire planet! Resembling an oversized long-legged wombat, Diprotodon was truly the king of Ice Age Australia. The cause of its extinction around 40 thousand years ago is heavily debated. The leading hypotheses developed to explain its extinction are centred around climate change associated with the last glacial cycle, or human impacts (such as through overhunting). The debate is one of the most polarised in Australian palaeo-sciences. The difficulty in determining the cause of the extinction of Diprotodon and other megafauna, is in part, due to a lack of reliable data with which to test the leading extinction hypotheses- especially well-dated fossil records. But here, Ian and I saw a great opportunity to travel out to the new fossil site, not only to excavate the new specimen, but to collect some samples critical for dating.

The Diprotodon is over 90cm long!

The Diprotodon is over 90cm long!

Ian and I met with the discoverer and travelled down to the creek where the skull was found eroding out of an ancient deposit. Our jaws dropped when we saw it- it was a monster, measuring around 90 cm in length! With the help of the discoverer, we excavated the skull. During the day, I spent a bit of time documenting the geology of the area, as well as collecting some sediments for optically-stimulated luminescence (OSL) dating. There was also a little bit of charcoal buried in amongst the skull- I also collected it with the plan to date it using radiocarbon methods.

The plaster jacket containing the skull weighed around 170 kg!

The plaster jacket containing the skull weighed around 170 kg!

 

We put a plaster jacket around the skull to protect it, but it was just so enormous that the three of us were not able to carry it. We were able to lift it with some difficulty- Ian and the local on the back-end, me on the front, but we just couldn’t move it out of the deposit- we sunk right down into the mud and couldn’t move. We ended up going back to the vehicles and drove around the neighbourhood looking for help. We came across some electrical tradies and asked them for assistance- thankfully they said ‘yes’! It took five of us to get the skull up out of the gully, carried across the field, and lifted into the back of Ian’s ute. We estimated that the plaster jacket, with the skull and surrounding sediment, weighed around 170 kg!

Ian is currently in the process of preparing the skull. It’s starting to look pretty good too- one of the best preserved skulls that has ever been discovered, not only on the Darling Downs, but across the entire continent. I’ll be sure to post some pics of the skull when it is finally cleaned up!

Excavating the owl’s dinner plate

Undergraduate student volunteer Nick Wiggins (UQ) excavating at Colosseum Chamber

Recently I wrote about an ongoing study at Colosseum Chamber, an extensive fossil deposit located at the Capricorn Caves tourist park, just north of Rockhampton in central eastern Queensland. The chamber occurs within an ancient cavernous limestone, which itself dates back to the Devonian (over 350 million years ago). The Colosseum deposit is around 2 m deep and, to put it simply, is chockfull of the fossilised remains of an ancient feast. The bones are the leftovers – the undigested parts – from the feeding activities of owls over the past several thousand years. The fossils consist of a huge number of teeth, jaws, and post-cranial skeletal elements from a range of small-bodied species such as frogs, skinks, bandicoots, dunnarts, antechinuses, planigales, possums, and rodents.

Having first identified the deposit back in the mid-2000’s, we were lucky enough to obtain some recent research funding from the Ian Potter Foundation, The University of Queensland and Australian Research Council to continue our excavations. In mid-April, we ventured out for a new fieldtrip to the site.

Lower jaw of brushtail possum from the Colosseum Chamber fossil deposit

The trip was led by Dr Julien Louys from UQ with me as second-in-charge, and we were joined by other colleagues from UQ, the Queensland Museum, and volunteers including PhD student Jonathan Cramb (QUT) and undergraduate student Nick Wiggins (UQ). Although these were the folk who did most of the digging, the trip just would not have been possible without the generous support of the Capricorn Caves tourist park who put us up and allowed access to the cave, and local cavers, Noel and Jeanette Sands who also assisted with the excavations (Noel also cooked up an awesome barbie for my last night in town!).

From our preliminary dating study, we know that the deposit accumulated over the last 80 thousand years. This is a particularly exciting time period to be investigating. The last 80 thousand years included an episode of great climatic upheaval, numerous species extinctions, and was also the time that saw humans first set foot on the continent. The goal of our work is to use the Colosseum Chamber

Maxilla of southern brown bandicoot from Colosseum Chamber. The species is extinct from the region today.

fossil record to explore how the local faunas reacted to such prehistoric events. Having a robust understanding of species response(s) to past environmental perturbations is absolutely fundamental in informing modern conservationists and climate scientists about the possible effects of climate change on living populations.

Previously we had excavated the deposit to a depth of around 90 cm from the modern cave floor. This year we were able to extend the dig much deeper, to almost 2 metres deep. The digging got quite difficult the further down we got- both logistically (it’s not particularly comfortable working in such a cramped environment with other sweaty, smelly palaeontologists!), and because we hit a lot of large chunks of limestone, signalling that we were getting close to the bottom of the deposit.

Lower jaw of an extinct rabbit rat, recently discovered by PhD student Jonathan Cramb

Thousands of kilograms of sediment were removed from the cave in buckets and were taken down to the bottom of the ridge for sieving. Digging is fun, but the sieving is where you get to see all the amazing fossils that the deposit contains. Jonathan, our resident rodent expert, recently discovered a new fossil species of Rabbit Rat from Colosseum Chamber (named Conilurus capricornensis– the species name is in honour of the Capricorn Caves tourist park), and was extremely excited to see a whole heap more of his unusual rodent emerge from the sieving!

During the trip we were able to collect new samples for dating including charcoal (radiocarbon dating), straw stalactites (uranium-series dating) and sediment (optically stimulated luminescence dating). Getting those samples dated is now the next major job, not to mention the huge amount of bones that need to be taxonomically identified and sorted into skeletal groups. No doubt we have a mammoth task in front of us, but the information that we can potentially extract from the deposit is just so critical and important for modern conservation that we just can’t ignore it. Updates to come!

Sifting through 80 thousand years of owl spew

Dr Julien Louys at the Colosseum Chamber excavation

This definitely isn’t the most glamorous title that I’ve ever come up with, but it’s certainly one of the most accurate! Situated at the Capricorn Caves tourist park, about 20 minutes north of Rockhampton in central eastern Queensland, lies one of the most important Quaternary-aged cave fossil deposits in Australia. The deposit, situated in Colosseum Chamber, is 2 m deep and contains numerous bones of small-bodied vertebrates such as rodents, dunnarts, antechinuses, bats, frogs and quails. By ‘numerous’, I mean ‘ridiculously abundant’- there are literally hundreds of thousands of bones in the deposit.

So how did they all get there? Well, that’s what the title of this post is all about! Owls, believe it or not, play a major contribution to the formation of fossil deposits. They are typically nocturnal, so conduct most of their feeding activities at night time. Being relatively small-bodied predators, they can only take relatively small-bodied prey. During the daytime, they commonly roost in caves, venturing out at night time to hunt,

Excavating at Colosseum Chamber

but will later return to the caves to consume their feast. In most cases, they will rip their prey apart using their tough beaks and strong claws before they swallow it. The smaller prey chunks will be partly digested in the stomach. The bits that aren’t digested, which normally include things like teeth, bone, fur and feathers, are regurgitated into pellets and drop to the floor of the cave. If you have enough owls out there using caves, hunting, digesting, and regurgitating, overtime they’ll accumulate a huge amount of bones, and if palaeontologists are lucky enough, they’ll often be incorporated into the cave fossil record.

That is exactly what we see in the Colosseum Chamber fossil deposit. So how do we know that the bones got there via owls? Well, most of the bones that we have identified are those from small-sized vertebrates, mostly less than about 500 grams- just the right size to be easily carried by an owl. Most of the fossil bones are relatively intact- we have an incredible amount of well-preserved teeth, jaws, and skeletal elements. Had the chief predator been a toothed mammal, such as a quoll, the bones would typically be all crunched up and we would see tooth marks all over them… but we don’t. Another key sign is that the bones belong to animals that are typically most active at night themselves. So, unfortunately for them, they were in the wrong place at the wrong time to become owl chow… but right place and right time to be incorporated into the fossil record.

PhD student Jonathan Cramb sifting through the sediment in search of fossils

The deposit was originally identified by Dr Scott Hocknull from the Queensland Museum back in the mid-2000s. Working alongside Scott, we conducted preliminary excavations and realised the potential for the site. Our initial dating study, supported in part by the Australian Research Council, as well as the Australian Institute of Nuclear Science and Engineering, has shown that the deposit spans roughly the last 80 thousand years.

Most recently, the project was passed onto my colleague Dr Julien Louys from The University of Queensland. Julien, Scott and I were successful last year in obtaining some generous funding from the Ian Potter Foundation to conduct a more extensive study on the Colosseum Chamber deposit. Julien was also awarded a post-doctoral fellowship from The University of Queensland which will not only support Julien’s salary, but also help towards costs for fieldtrips and laboratory analyses. We have a fieldtrip coming up in mid-April, so I will be sure to provide an update to the new work soon!

Fieldwork at Chinchilla

Dr Julien Louys collecting dating samples

An incredible Pliocene vertebrate fossil site occurs at Chinchilla, about four hours drive west of Brisbane, Australia. Fossils have been known from the area since the 1800’s with numerous species identified to date. The fossil fauna includes animals as diverse as diprotodontoids (the same family of mega-marsupials as Diprotodon), short- and long-faced kangaroos, wombats, koalas, and lizards. Despite the richness of the assemblage, plus fact that Chinchilla represents one of few fossil deposits of its age in Australia, relatively little research has been directed towards understanding the significance of the site.

Part of my new work, in collaboration with Dr Julien Louys (also from The University of Queensland) and Joanne Wilkinson (QueenslandMuseum), aims to address this knowledge gap. Julien is presently writing a review on the fauna, but without firm geochronological control on the deposits, we are unsure exactly how old the site actually is. By comparing the types of fossils found at Chinchilla to those from other deposits acrossAustralia, we are confident that the site is Pliocene (between 2.6-5 million years old), but where in the Pliocene is unclear.

Joanne Wilkinson surveying the site

The goal of our recent fieldtrip to the site (late February 2012) was to collect new samples for dating. The samples predominantly included sediment that is associated with the fossils. In late March, the samples will be passed on to our colleague, Dr Andy Herries from the LaTrobe University in Victoria, who is a specialist in palaeomagnetic dating. If the dating is successful, they will be the first analytical dates ever produced for Chinchilla.

Dating is notoriously difficult, time consuming and expensive, but absolutely critical for placing the Chinchilla fossil site into a reliable temporal framework for understanding its significance on a continental scale. Fingers crossed that we can get some new dates very soon!

Redating the Neds Gully megafauna deposit

Debate over the timing and causes of extinction of Australia’s Pleistocene megafauna has become polarised in part due to a paucity of reliable geochronological information for the extinct forms. Thus, it is difficult to accurately test leading extinction hypotheses in relation to human continental colonisation and climate change events.

The Neds Gully megafauna site on the Darling Downs, southeastern Queensland, has a central role in the extinction debate. Although it is commonly regarded as the continent’s youngest megafauna-bearing deposit (possibly dating to around 40-50 thousand years ago), the provenance of existing dates to the fossils and general stratigraphy of the site has never been formally demonstrated. Thus, the significance of the deposit with respect to the broader extinction debate remains unclear.

So there remains the question: Is Neds Gully really the youngest megafauna fossil site in Australia? Providing the answer to this important question has been the focus of some of my recent work on the Darling Downs.

The Neds Gully fossil deposit was excavated in the 1990’s, long before I was even interested in studying palaeontology. Numerous specimens were collected and accessioned into theQueenslandMuseum. Unfortunately, a comprehensive description of the site was never published. Over the past couple of years, I’ve been revisiting the site to try to determine exactly where the fossils and dating samples were collected from. Fortunately, I have had the help of my friend and colleague, Ian Sobbe. Ian wears a couple of different caps- one as a local farmer, and the other as an amateur palaeontologist. Ian was one of the original excavators of Neds Gully, so finding the site again was no problem.

We reopened the site, bringing in some earth moving equipment to clear overgrowth and sediments that built up over the deposit. We were able to identify the stratigraphic horizon that produces the fossils and even found some new specimens in the process. Armed with some aluminum tubes and a sledge hammer, Ian and I took some new sediment samples for dating. The samples were sent to my colleague, Dr Andrew Murray atAarhusUniversityinDenmark. Andrew is a specialist in optically stimulated luminescence (OSL) dating and was able to produce some new dates for us.

In additional to the OSL dates, I also produced new uranium-thorium (U/Th) dates directly on the fossils using the thermal ionization mass spectrometer (TIMS) at the Radiogenic Isotope Facility (The University of Queensland). The new dates are particularly exciting for us and match perfectly with the OSL dates.

Without giving too much away, the results broadly support the idea that Neds Gully is one of the youngest megafauna deposits inAustralia. However, we have not found evidence for a mass extinction event as commonly as been suggested. I’m currently in the process of writing this work up, with a view to submit it to a scientific journal very soon, so watch this space!

Palaeoecology during the Ice Ages in northeastern Australia

Main study sites in northeastern Australia

One of the challenges of working in academia is the constant need and pressure to secure research project funding. The main research funding body in the country is the Australian Research Council (ARC). They offer a number of schemes for supporting research, all of which are incredibly competitive.

In 2011, I applied for funding under a new ARC scheme called the Discovery Early Career Research Award (DECRA). The DECRA’s are intended for junior researchers, generally with less than five years post-PhD research experience. There was an incredible number of applicants in the round – over 3180 – for just 277 awards (success rate of less than 9%). The outcomes were announced in mid-November, and to my surprise and delight, my application was successful! My funding will secure my research program for the next three years.

My study will focus on developing a baseline understanding of faunal responses to climate change and environmental perturbations through the Quaternary in northeasternQueensland. The region is unique for the concentration of a vast array of well-documented Quaternary palaeoclimatic archives (e.g., deep marine pollen cores, records in lacustrine sediments, rainfall archives from speleothems, offshore ostracod and foraminifer geochemical records). Such records extend back several hundred thousand years, through numerous glacial-interglacial cycles, and document how the region’s climate and environments have evolved through to the present. Strikingly, they provide key information on the timing and duration of prehistoric dry intervals, and document a long-term trend in the weakening of the Australian Monsoon: patterns of climate change that mirror those that are predicted to continue into the future.

Diprotodon skeleton at Floraville

Although there is an increasingly robust model of Quaternary climate change for the region, a lack of well-documented faunal records hampers efforts to understand prehistoric biological responses to the climate perturbations. However, that is not through want of appropriate fossil sites, but rather, lack of investigation. Areas such as Chillagoe are renowned for their unique Pleistocene faunas and contain animals such as the enigmatic Quinkana fortirostrum (extinct terrestrial crocodile) and Propleopus chillagoensis (giant carnivorous rat-kangaroo), two species that are known from nowhere else on the continent. Yet, we have little or no knowledge of their palaeoecology, palaeobiology and extinction simply owing to a lack of significant investigation in the region (the last major studies in the area ceased in the 1970’s). Other areas such as Floraville contain remarkably diverse Plio-Pleistocene faunas (including both megafauna and smaller-bodied species), but only preliminary results have ever been published. Well-documented sites, such as Wyandotte, preserve highly significant faunal assemblages previously thought to date to around the time of terminal megafaunal extinctions, but they now require re-dating because the previously established dates are no longer accepted. It is clear that northeastern Australia can yield critical data for understanding ongoing patterns of faunal change.

A major goal of my project will be to quantify the precise timing, magnitude, rates of climatic and environmental changes, and the long-term response of northeastern Australia’s terrestrial faunas to such events. For this reason, fossil deposits with long depositional sequences and well-preserved faunal remains in potentially easily datable contexts will be the focus of the research. Strategically, this includes targeting fossil assemblages that represent accumulation at different times through interglacial/glacial cycles, both before and after the arrival of humans on the continent, as well as more recent deposits within the timeframe of European colonisation (such as Carrington Cave, a site that contains the introduced house mouse, Mus musculus).

I’m currently planning fieldwork for the upcoming year. In late May, I will be heading up to the BrokenRiverarea. Several fossil deposits have already been identified from caves in the area by my friend Doug Irvin, a long-serving member of the Chillagoe Caving Club. Through June-July, I will be trekking to the Floraville area, just south of the Gulf of Carpentaria. Fossils have been collected from the region for the past 40 years by my colleagues Prof. Michael Archer and Henk Godthelp, both of the Universityof New South Walesin Sydney. We’ll be visiting the main sites, collecting new fossil specimens and hopefully some dating samples. In 2011, we excavated one of Australia’s most complete Diprotodonskeletons. I collected some dating samples at the time, but am still waiting on the results.

Waterfall in the Leichhardt River, Floraville Crossing

I’ve almost completed my first manuscript relating to the project- a direct fossil dating study. The purpose of the study is to determine the age of the specimen and to demonstrate the utility of the direct fossil dating approach of museum specimens using U-series methods. The specimen, a maxilla of the extinct marsupial ‘tapir’ (Palorchestes azael) was collected from the cave in 1977 and curated into the fossil collections of theQueenslandMuseum before being sequestered for dating. The results demonstrate that the specimen is between ~137–199 thousand years old, thus, predating the hypothesised time of final megafaunal extinctions. The result is significant in that it is the most northerly mainland dated recorded for any of the extinct Australian megafauna and represents one of the youngest reliably dated records for the species. The stratigraphic relationship of the dated specimen to other fossils from the cave is unclear. I hope to be able to submit the manuscript to a journal in the next month or so.

With the fieldwork, lab work, and paper writing, it’s bound to be a busy year!