Fossilised body organs in fish

How old do you think the oldest fossilised heart is? 1 million years? 100 million? More? We found a 380 million year old fossilised heart, as well as stomach, intestine and liver in ancient jawed fishes, published today in the journal Science. (Previously the oldest known fossilised heart was described from a measly 100 million years ago…)

Finding soft tissue preserved in fossils is rare, and finding 3D preserved fossils is remarkable, so the combination of these in 380 million year old animals is mind-boggling! These fish are the ancient armoured placoderms from the famous Devonian (359-419 million years ago) Gogo reef lagerstätten (meaning site of exceptional preservation) in northern Western Australia.

Gogo fish diorama at WA Museum Boola Bardip. Credit: Curtin University

Powerful imaging techniques such as synchrotron scanning by the European Synchrotron Radiation Facility in France, and neutron tomography at the Australian Nuclear and Science Technology Organisation (ANSTO) in Sydney (Australia) enabled us to see inside the specimens while they were still embedded in limestone and construct 3D models of the bones and soft tissues inside. I still remember the day sitting at ANSTO with lead author Prof. Kate Trinajstic and beam scientist Dr Joseph Bevitt looking through the latest neutron scans when we found one of the heart specimens in a placoderm called Compagopiscis.

Joseph Bevitt, Alice Clement and Kate Trinajstic at the ANSTO neutron facility in Sydney.

Importantly, the shape and position of the heart (the oldest ever found!) signifies an important step in evolution of the vertebrate body plan, and the lack of lungs suggests these organs only evolved once later on in the bony fishes.

It was so exciting to be included in this project with a kick-ass team spanning Australia, Sweden, and France with my co-authors Kate Trinajstic, John Long, Sophie Sanchez, Catherine Boisvert, Daniel Snitting, Paul Tafforeau, Vincent Dupret, Peter Currie, Brett Roelofs, Joseph Bevitt, Mike Lee and Per Ahlberg.

These Gogo fossils just keep on giving! If you would like to learn more, you can read an article by Kate and John in The Conversation or this one from Cosmos Magazine (complete with a few extra dorky pics of me “science-ing”.

Palaeo Jam!

Haven’t had your palaeo fill this National Science Week yet? Come along on August 25th for the inaugural recording of PALAEO JAM, a new Australian palaeontology podcast from Michael Mills of Heaps Good Productions.

“Palaeo Jam is a podcast exploring a range of issues in science and the community, through the multidisciplinary aspects of, and public fascination with, palaeontology. It is an Australian based palaeo podcast with this initial launch and live record at Flinders University. For the live record, two episodes will be recorded in front of a live audience, followed by a QandA.”

Episode 1- “What’s the point of palaeontology?” featuring Dr Aaron Camens, and PhD Candidate Phoebe McInerney.

Episode 2- “Life as a palaeo mum” with Dr Alice Clement and Dr Vera Weisbecker.

***LISTEN ON PODBEAN HERE***

Drinks and other goodies available on the night. Register your attendance here: https://www.eventbrite.ca/e/palaeo-jam-podcast-launch-tickets-376247826377?aff=ebdssbdestsearch&keep_tld=1


Fossil lungfish “brains” in eLife

Our latest article “Morphometric analysis of lungfish endocasts elucidates early dipnoan palaeoneurological evolution” was published yesterday in eLife.

In the way that many projects tend to go, the work for this article is several years in the making. I developed the seed of the idea during my time at Uppsala University (Sweden), and have been collaborating closely with Dr Tom Challands (University of Edinburgh) for several years to bring it to fruition. Together, Tom and I pooled our lungfish endocrania to more than double the number of those with “endocasts” known.

A cranial endocast is the internal space within the skull where the brain sits. As only the hard, bony parts of animals tend to fossilise we rely on the shape of these spaces to make inferences about the (now long gone) brain within.

Using synchrotron and micro-CT scanning technology, we were able to scan six new lungfish fossils to create virtual models of their endocasts. The fossils need to be exceptionally-preserved in 3D to be able to conduct these analyses. The fossils came from different sites from around the world (Australia, USA, Russia and Germany), but all hailed from the lungfish “heyday” of the Devonian Period (359-419 million years ago).

By combining these six new fossil models with all of the other lungfish endocasts known were were able to compile a dataset of 12 taxa which we then measured. The skulls of Devonian lungfish are highly variable in shape, and so we predicted that different endocast (brain) regions would undergo elongation as the external skulls changed shape.

Figure 12 from the eLife paper showing 10 fossil lungfish endocasts.

Along comes our heroic collaborator, Prof. Richard Cloutier (UQAR), who then had the unenviable task of making sense of our messy measurements and conducting some impressive morphometric analyses (a way of quantifying shape) despite our dataset having several missing variables (something not usually accommodated well in many morphometric analyses). We used several methods, including Bayesian Principal Component Analyses (BPCA) and PCA for incomplete data (InDaPCA) to untangle how the shapes of the endocasts differed from one another.

Figure 10 from the eLife paper showing a BPCA plot.

Our findings showed that contrary to our hypothesis where we thought different brain regions would tend to elongate within long skulls, most of the elongation (regardless of skull shape) tended to happen in the olfactory (sense of smell) region. We consider that sense of smell has remained an important sense throughout lungfish evolution.

We also uncovered some interesting things happening within the labyrinths (inner ears). The shape of inner ears can give a lot of information about an animal related to its sense of hearing, but also how it moves (locomotion). More investigation needs to be done but this may point to differing sensory requirements as lungfish evolved from deep sea animals to those living closer to shorelines in freshwater environments.

Ultimately we are continuing to learn more about brain evolution in this most fascinating group, the lungfish, which can in turn aid our interpretation of other groups -including our earliest fishy ancestors as they took the leap from water to land. Big thanks are due to all co-authors Tom Challands, Richard Cloutier, Laurent Houle, Per Ahlberg, Shaun Collin, John Long, as well as the editorial and reviewing team at eLife. If you would like to know more then I encourage you to read the article directly from eLife. All scan data is freely available for download from MorphoSource or Dryad.

Palaeo-matrescence

I’m not sure that I have much wisdom to impart as I’m only writing this as a very new “parent in palaeo”. My son is just 9 months old and I’m imminently returning to work following maternity leave. It has been, as everyone says, a life-changing time and I have (mostly) enjoyed my days at home with the little one.

Before going on maternity leave I expressed some concerns about how being a mother in palaeontology/science/academia might potentially impact my career trajectory. I knew I worked in a male-dominated field, but it never felt more apparent than when I became pregnant. I wanted to seek advice from colleagues who had navigated the same journey as me, but it was difficult to find people in the same boat. I could see plenty of “parents in palaeo”, but looking for mothers (in the traditional, biological sense) was a harder task. Where are they all?

Alice at ~8 months pregnant (2021)

Unfortunately the career stage when most people become parents is during the vulnerable EMCR (Early – Mid Career Researcher) years when the majority of researchers are still navigating short-term, insecure contracts. It is no surprise then that it is during the EMCR stage we see the greatest effects of the “leaky pipeline”. (And relatedly, the numbers of women progressing from junior to senior levels suffers from what I’ll call the dreaded “scissor graph disappearing act”). I have no doubt that any time away from work compounds differences in output in our very competitive funding landscape and can therefore influence potential future success. The recent mothers I could see in STEM (in Australia particularly) were few and far between, and most of them continued to juggle insecure work.

Furthermore, years of insecure work throughout one’s late 20s and 30s can influence the decision about when to start a family. This was certainly the case for me, I had hoped for some job security prior to becoming a mother, but in the end I felt like I couldn’t wait much longer. I had my first child at age 37 and I don’t know if we will have any more. I do consider that if I had had secure work earlier in my career I might have started child-bearing younger and potentially had more children. In this way, a choice to pursue a career in science can directly impact one’s fertility.

Alice at home with baby Edvin

Similarly, academia often requires workers to relocate to new cities, new countries, new continents, taking people away from their traditional support networks such as extended families. This may influence when, and in what capacity, a parent might return to work after the birth or adoption of a child. Our families are based in Melbourne and Sweden respectively which renders our “village” pretty distant when we might otherwise call upon their help.  

Many people told me that I would “feel differently” about work once I became a mother (I note that no one ever said this to my partner, Niels). In some ways I think I was lucky that my work is a passion of mine, and being able to remain connected was a positive for me. Being a full time parent at home with a baby can be isolating and relentless in the day-to-day, and being able to check in occasionally with students and colleagues gave my brain a welcome escape from nappies, tantrums and breastfeeding. However, there were also times when I felt overwhelmed and frustrated to not be able to contribute as I would have liked, either due to the lack of time or headspace (usually both). Science is a highly collaborative pursuit, and the cycles of grant deadlines, student projects, and research papers doesn’t take a pause just because you do.

Alice with Edvin (6 months)

I’m lucky to have good support from my supervisor, colleagues and university so I feel positive about my immediate future. The long-term effects of choosing to have a family remain to be seen but I’m hopeful that our government and institutions can better accommodate working parents in the years to come.

I lived and worked in Scandinavia for a few years early in my career and saw how their more generous parental leave policies, with time allocated to both parents, and highly subsidized/universal childcare supported families and careers. I believe that Australia can do a lot better in this respect to improve equality at home and in the workplace. It is time for fathers and other non-birthing parents to take more time out of their careers to care for children too.

However, far from “changing priorities” and “feeling differently” about my career, I absolutely relish the idea of returning to work. I hope that by writing this piece I am increasing the visibility of at least one mother in STEM who is doing her best to (hopefully!) thrive as a “parent in palaeontology”.

Gogo grant funded!

Father Christmas came early this year! Our Discovery Grant “The Devonian Gogo Fauna: Diversity, Palaeoecology and Global Significance” from the Australian Research Council (ARC) was funded! This grant gives us three years of funding for research and to support students and other staff associated with the project.

John Long (Flinders Uni), Kate Trinajstic (Curtin Uni) and I are Chief Investigators, and we’ll be collaborating with a fantastically diverse range of international partner investigators including Carole Burrow (Queensland Museum), Per Ahlberg (Uppsala University), Derek Briggs (Yale University), Zerina Johanson (Natural History Museum London), Christian Klug (University of Zurich) and Richard Cloutier (University of Quebec).

Prof. John Long, Dr. Alice Clement, and Prof. Kate Trinajstic attending the International Symposium of Early and Lower Vertebrates in Poland, 2017.

The Late Devonian Gogo Fm. in Western Australia (380 myo) is one of the richest and best-preserved assemblages of fossil fishes & invertebrates on Earth. We will reconstruct the trophic relationships of the reef and test the resilience of the ancient reef ecosystem.

Additionally, we will work with local indigenous stakeholders to assess the heritage significance of the site. We aim to develop a long-term management plan to protect and conserve this amazing site and help to grow geotourism in the region.

I believe that Gogo is the best fossil fish site in the world and I can’t wait to get back there in the coming years with our collaborators, and see what we can achieve with this crack team of researchers we’ve assembled. Merry Christmas to us, indeed!

Dr. Alice Clement with a fossil find at Gogo in 2008.

New paper on tetrapod-like fish from Queensland

Hello! I’m taking a brief break from my maternity leave to tell you about my latest paper, published last week in the Journal, PeerJ; A fresh look at Cladarosymblema narrienense, a tetrapodomorph fish (Sarcopterygii: Megalichthyidae) from the Carboniferous of Australia, illuminated via X-ray tomography.

Four panels: a photo of the specimen, a radiograph of the specimen, a tomogram (slice) of the specimen, and a 3D model of the specimen. Image credit: Alice Clement.

In my paper we use microCT and synchrotron technology to image some spectacular 3D fossils of a fish known as Cladarosymblema from about 330 million years ago in what is today known as Queensland, Australia.

Cladarosyblema was a type of tetrapod-like fish known as a ‘megalichthyid‘. These fish grew to large sizes, lived in freshwater environments, and would have been fearsome predators. They were one of the few tetrapodomorph groups that survived the end Devonian extinctions, and persisted up until the Permian Period (299-252 mya). Cladarosymblema is the only megalichthyid known from Australia, and one of just two known from the ancient southern supercontinent, Gondwana.

Cladarosymblema was originally described in 1995 from several specimens, but using scanning technology we were able to uncover much of its internal anatomy that had until now remained hidden. In particular we could describe the gill arch skeleton, parts of the shoulder girdle, vertebrae and upper roof of the mouth bones (palate).

Additionally, we were also able to isolate the cranial endocast from Cladarosymblema, which gives insights into the size and shape of the brain of this animal. The area for the pituitary gland (so-called the master gland) is relatively large, suggesting a significant role in regulating various important endocrine glands. The overall shape of the endocast is more similar to that of early terrestrial vertebrates (tetrapods) than to most of the fish left living in the water. Was it some of these adaptations that enabled Cladarosymblema’s relatives to colonise land?

Furthermore, the membership of the ‘megalichthyids’ has been controversial, with several recent studies finding conflicting results. We ran a phylogenetic analysis (analysis of relationships) and found that the megalichthyids form a natural clade (are monophyletic).

Section of the evolutionary family tree showing that megalichthyid fishes form a natural clade.

I want to thank the Queensland Museum for allowing us access to the beautiful specimens, as well as all of my co-authors, reviewers, and the editor who handled the paper at PeerJ. All of the scan data and 3D models are available at MorphoSource, and the phylogenetic matrix can be accessed on MorphoBank.

Cladarosymblema narrienense head restoration in right lateral view. Image: John Long.

A different kind of project

I’ll be stepping back from my monthly updates a bit as I prepare to go on maternity leave next week. It’s exciting, terrifying & overwhelming, and I understand it will change the life of me and my partner forever. Bubba is due in just over two weeks!

This is what a scientist looks like (8 months pregnant).

I’m all too painfully aware of what the statistics say and how the penalty of motherhood continues to impact women disproportionately compared to their male counterparts (fathers get promoted, while women are pushed out via the #leakypipeline).

Figure 1. Academic profiles by gender; natural and physical sciences 2007.
Source: DEEWR Selected Higher Education Student Statistics 2007; Department of Education,
Science and Training, Special Report, FTE Staff in AOU Groups, 2007.

Even today, it was confronting to look around and struggle to find role models who had become mothers and managed to succeed to senior levels in STEM #WomeninSTEM (although I’m inspired by the few exceptions I do see).

I did also manage to be #PregnantInTheField relatively early on. Very doable (with a few extra toilet breaks and early nights to bed, and some extra loose pants!) I did miss being able to enjoy a glass or two of red by the campfire at the end of the day, however.

Dr Clement, pregnant in the field, holding a fossil find.

I am really hopeful that things continue to improve and that my career isn’t too negatively impacted by choosing to have children. Sometimes I can’t help but wonder what is the point of all the initiatives to encourage girls into STEM if we don’t retain women in STEM?

AsiaEvo Conference

The last 18 months have transformed many, many things, including the world of scientific conferences. The pivot to online virtual events means great things for accessibility and inclusion (although I do miss many things about the old-style in-person events too).

This week I gave a talk at the 2nd AsiaEvo Conference, which was organised as a joint meeting with the 23rd Annual Meeting of Society of Evolutionary Studies from Japan. I was one of the invited speakers for a symposium “The rise of fishes: the origin and early evolution of non-tetrapod vertebrates from a paleontological perspective” organised by Min Zhu and You-an Zhu, two great colleagues from IVPP in China.

I gave my talk “Morphometric Analysis of Lungfish Endocasts Elucidates Early Dipnoan Palaeoneurological Evolution” from the comfort of my own office in Adelaide, Australia, on early brain evolution of fossil lungfish (one of my absolute favourite topics in the world!) I can’t say much more about it right now as I’m preparing a paper for submission soon on this very topic.

There were some great talks in our session, but I especially enjoyed the work from Xindong Cui (also from IVPP) on new material of Youngolepis, a lungfish-like fish from the Lower Devonian of Yunnan, China. I look forward to seeing his work published soon!

National Science Week 2021

National Science Week 2021 is fast approaching! During 14-22 August Australia-wide there is a plethora of science-themed events, tours and more for you to get involved in.

I’m involved in a few different events happening during the week:

I’m attending the Official Launch Lunch being held at the South Australian Museum with Mr Brian Oldman, (Director of the South Australian Museum), Hon David Pisoni MP and Prof Caroline McMillen AO, (Chief Scientist for SA), in a celebration of science (la di da!)

Secondly, I’m an invited speaker at Seeing Things Differently held by Micro-X at Tonsley on Friday 20th August where I will present my talk ‘A virtual revolution for fossil hunters – how CT scanning is transforming palaeontology’ to registered school groups coming by for a tour of Adelaide’s Micro-X factory.

I’ve been invited to be part of a fun night of science and cheeky debate between four teams representing different STEM fields called My Science Rulz, Your Science Droolz. It’ll be a battle between palaeontology, astronomy, maths, and neurogenetics on Tuesday 24th August at The Gov and should be a good laugh.

And lastly, I’m helping to organise an event being put on by the Royal Society of South Australia, thanks to support from Nat Sci Week, called the Royal Society Show Case Science to celebrate and promote to the public the diverse research our members undertake to advance knowledge in SA. The night will include lightening talks and distinguished panellists making their case for science on Wednesday 18th August. This event will be held in person at the SA Museum, but guests are also available to join in online and attendance is free! Please check it out. #ScienceSouthAustralia

So it is shaping up to be a busy, but fun-filled and science-y week! I urge you to check out the website to see if there is an event that tickles your fancy so you too can get involved.

100 years of fossil brains

2021 marks 100 years since the birth of palaeoneurology, the study of “fossil brains”. As its name suggests, palaeoneurology combines the study of fossils with neural evolution.

On this day in 1921, a young vertebrate palaeontologist from Frankfurt, Germany, Johanna Gabrielle Ottilie “Tilly” Edinger, submitted her thesis describing an “endocast” of a Mesozoic marine reptile, Nothosaurus. An endocast is a mould of the internal space of the skull which houses the brain; these can form naturally via sediment infill, or can be recreated using virtual models.

To mark the occasion, I wrote an article for The Conversation. Please follow this link to read it: “Remembering Tilly Edinger, the pioneering ‘brainy’ woman who fled Nazi Germany and founded palaeoneurology“.

I was inspired to write this article following conversations with Dr Susan Turner (co-author of “Rebels, Scholars, Explorers: Women in Vertebrate Paleontology“).

Tilly Edinger’s pioneering work has allowed us to understand much more deeply the evolution of the vertebrate brain, and continues to inspire other researchers to carry on her important legacy.

I’ve included a list of some active “brainy” women currently working in palaeoneurology below if you would like to learn more about specific groups of vertebrates (I guess it can’t be fish all the time!)

ScientistAnimal groupWhere they work
Dr Amy BalanoffDinosaurs and birdsJohn Hopkins University (USA)
Dr Amélie BeaudetHominids (apes and early humans)University of Cambridge (UK)
Dr Ornella BertrandMammalsUniversity of Edinburgh (UK)
Dr Alice ClementFish and early tetrapodsFlinders University (Australia)
Dr Elizabeth FerrerBirdsStony Brook University (USA)
Dr Sam GilesFishUniversity of Birmingham (UK)
Dr Maria Eugenia GoldDinosaurs and birdsSuffolk University (USA)
Dr Jing LuFishIVPP (China)
Dr Gabi SobralReptilesStaatliches Museum für Naturkunde (Germany)

References:

  • Edinger T. 1921. Über Nothosaurus, Ein Steinkern der Schädelhöhle. Senckenbergiana 3:121–129.
  • Buchholtz EA, and Seyfarth E-A. 1999. The gospel of the fossil brain: Tilly Edinger and the science of paleoneurology. Brain Res Bull 48:351-361.
  • Buchholtz EA, and Seyfarth E-A. 2001. The study of “fossil brains”: Tilly Edinger (1897-1967) and the beginnings of paleoneurology. BioScience 51:674-682.