VP fieldtrip to Victoria

I was back in the office after a week away on the Flinders University 3rd year Vertebrate Palaeontology field trip to Victoria (in south-eastern Australia).

First, we explored some Silurian and Devonian deposits in the Grampians (Gariwerd on Jardwardjali land), including some spectacular trace fossils from the Glen Isla Quarry and Homestead, whilst camping at the beautiful Buandik Campground.

Silverband Falls, Grampians N. P.

Next we moved on to Mansfield in the foothills of the Victorian Alps (Taungurung) to work on the Kevington Creek Formation of the South Blue Range (mid-Devonian), and the Devil’s Plain Formation (Carboniferous).

View from South Blue Range, Mansfield

These sites were relatively productive with us discovering many plant fossils (e.g. Lepidodendron), placoderms (including Bothriolepis, Groenlandaspis and Austrophyllolepis), and some tiny sharks teeth from Kevington Creek Formation.

I was pleased to find a block containing what looked like skull roof bones from a rhizodont (Barameda), a large predatory fish known to come from the Carboniferous deposits of “Fish Hill”. We also found numerous large spines from acanthodians (“spiny” stem sharks).

I found a block containing impressions of some rhizodont skull at “Fish Hill” in Mansfield

Lastly, we jumped through time on our way home to the Pleistocene of Warrnambool on the Great Ocean Road of western Victoria. There we saw megafauna trackways (including those from the marsupial “lion”, Thylacoleo) at Thunder Point and heard about human habitation of the Moyjil and Tower Hill area from >35,000 years ago, and possibly as long ago as 120,000 (!) from Dr John Sherwood.

Thunder Point, Warrnambool

We were so lucky to be able to run our fieldtrip this year after two failed expeditions last year (COVID-related). We got to visit some truly spectacular places, and found plenty of fish fossils so all in all, a great success, I’d say!

Another brainy paper

It has been a good month with another paper published last week. This one “Brain Reconstruction Across the Fish-Tetrapod Transition; Insights From Modern Amphibians” forms part of a special research topic in the Frontiers in Ecology & Evolution journal on soft tissue reconstruction (you guessed it!) over the fish-tetrapod transition.

I was very happy, along with my co-authors, to contribute to this special issue. My co-authors included Flinders PhD candidate, Corinne Mensforth, Dr Tom Challands from the University of Edinburgh in the UK, Prof. Shaun Collin from La Trobe University (Victoria, Australia) and Prof. John Long, also from Flinders University.

In this work we looked at the relationship between the brain and it’s “endocast” in some amphibians (frogs and caecilians), to compare with earlier work on lungfish and salamanders. The endocast is a cast or mould of the internal space of a hollow structure, in this case, the space inside the skull that usually houses the brain in life.

We did this to try and better inform our interpretation of fossil endocasts when the soft parts of the brain haven’t been preserved and only the hard, bony parts remain. I also wrote an article for The Conversation about this research, so if you’d like to know more please CLICK HERE!

Brains (pink) and endocasts (grey) of lobe-finned fish and amphibians.

New paper on fossil limb bones and bone marrow

We had a paper published today in the journal, eLife. The article, “New light shed on the early evolution of limb-bone growth plate and bone marrow” was written by an international team of researchers from Uppsala University in Sweden (Sophie Sanchez, Jordi Estefa, Grzegorz Niedźwiedzki), the European Synchrotron Radiation Facility in France (Paul Tafforeau, Camille Berruyer), Comenius University in Bratislava, Slovakia (Jozef Klembara), and of course, Flinders University in Australia (that’s me!)

Do you know where in the body your red blood cells are produced? For most of us, this occurs in the bone marrow within our “long bones” (in our arms and legs). But what about animals without arms and legs, like fish? They tend to produce blood cells (in a process known as haematopoiesis) in other body organs, such as their kidney or liver. This raises the question: at which point in evolution did blood cell production shift from body organs into long bones?

How tetrapods acquired new bone characteristics as they transitioned from water to land.
Image from article by Holly Woodward: https://elifesciences.org/articles/66506

Some researchers thought this might have occurred in the bones of the earliest backboned animals to evolve limbs (yes, you guessed it, we are talking about early tetrapods again!) before they moved from water onto land. To test this hypothesis, my good friend and colleague, virtual palaeohistology queen Dr Sophie Sanchez, together with PhD student Jordi Estefa, led this investigation into the microarchitecture of animals spanning the fish-tetrapod transition (stem-tetrapods, batrachians, and amniotes).

Classical histology, as well as three-dimensional synchrotron virtual histology, was used to identify which animals had humeri (upper arm bones) with an internal organization that would enable blood cells to be produced (similar to what we see in living reptiles and mammals). The earliest animals we investigated with open marrow cavities where haematopoiesis could have occurred, are 300 million-year-old stem amniotes called Seymouria and Discosauriscus. Contrary to previous hypotheses, this is significantly (at least ~60-70 million years) later than the first tetrapods that evolved limbs and crawled out of water and onto land!

Left: The 380-million-year-old lobe-finned fish, Eusthenopteron upper arm bone (humerus) has marrow processes forming a simple enclosed mesh of tubular structures that probably only served for the elongation of the bone. 
 
Right: The 300-million-year-old tetrapod, Discosauriscus, upper arm bone (humerus). Discosauriscus has marrow processes forming a complex mesh of tubular structures and small cavities that open up onto the large empty medullary cavity at midshaft, where a centralized blood-vessel mesh could allow the production of blood cells. 

E. S. Hills Medal

Wow. I’m thrilled and honoured to receive the E.S. Hills medal from the Geological Society of Australia today. The medal is awarded to a young (<40 years) Australian resident for outstanding contribution(s) to any branch of the geological sciences, anywhere. This medal, named for the impressive life and career of Edwin Sherbon Hills -whose interests and expertise were incredibly wide-ranging- is a great reminder of how broad and vast the geosciences are.

The medal was awarded during the 2021 Virtual AESC (Australian Earth Sciences Convention) . I must of course say a HUUUUGE thank you my nominators, and the entire awards committee for this privilege. Big congratulations also to Heather Handley for the inaugural Beryl Nashar Award, and to Alan Collins for the S.W. Carey Medal. (I’m humbled to be in their company). I hope that this award can inspire others to remember just how diverse and exciting the geological sciences are, and to keep digging until you find your niche. Thanks GSA!

Australian lungfish wins gold (for genome size)

There’s been some big lungfish news this week! A project led by Axel Meyer, Siegfried Schloissnig, Paolo Franchini, Kang Du, Joost Woltering and almost 15 others in their team, have published the full genome* for the Australian lungfish (Neoceratodus forsteri) in the high profile journal, Nature.

*A ‘genome’ is all of the genetic material of an organism and consists of DNA, while ‘genetics’ is concerned with the study of particular ‘genes’ and not necessarily the entire genome.

The genome of the Australian lungfish is absolutely huge at roughly 14 times the size of the human version, and is now the largest known in any animal. Previously the African lungfish, Protopterus, and then more recently the axolotl (salamander Ambystoma mexicanum), have been considered the record holders for this grand title.

This work by Meyer and team confirms the hypothesis that lungfish are the closest living lineage to the tetrapods (all amphibians, reptiles, birds and mammals), rather than the other group of living “lobe-finned fish”, the coelacanths. I like to say that in this way we can consider lungfish as our distant fishy cousins.

Figure 1 from the paper by Meyer et al. (2021) published in Nature showing the position of the lungfish (Neoceratodus) to tetrapods (https://www.nature.com/articles/s41586-021-03198-8)

For a time, the advent of molecular biology failed to definitively clarify this (known as the phylogenetic relationship) despite research on it spanning almost 30 years. The main issue was that the coelacanth, lungfish and tetrapod lineages are thought to have diverged from each other so long ago (about 420 million years ago!) which made piecing together their independent evolutionary molecular histories incredibly problematic. This is where palaeontology is absolutely invaluable for elucidating the relationships even between living animals when molecular methods may have their own limitations. Naturally I believe the best approach is to combine data from both lines of evidence to help us properly understand all life on earth today.

It was found that the lungfish had genes related to limb-like development in their fins, as well as some involved in air-breathing (lung surfactants and odour receptors) which were likely ‘preadaptations’ to living on land. The authors consider than these novelties found in lungfish -but not other fishes-, must have predisposed this group (sarcopterygians, the “lobe-fins”) to have been able to make that first foray onto land all those millions of years ago.

My photograph of a live animal, and 3D model of the Australian lungfish

These are just some of the reasons that I study lungfish in my own research, they are absolutely fascinating and hold the unique position as our closest fishy relatives (lungfish are more closely related to us than they are to a salmon or shark, for example). They are one of the best living representatives for helping us to understand what obstacles our distant tetrapod ancestors had to overcome to make their way from the water onto land almost 400 million years ago.

My own work researching lungfish has covered their air-breathing (Clement et al. 2016b; Clement & Long 2010a), muscles (Ziermann et al. 2017), brains (Challands et al. 2020; Clement et al. 2016a; Clement et al. 2016c; Clement et al. 2015; Clement & Ahlberg 2014), as well as fossils and the early evolution of the group (Gess & Clement 2019; Clement 2012; Clement & Long 2010b; Clement 2009; Long & Clement 2009). If you ever want to talk about lungfish, about these topics or otherwise, and specifically the Australian lungfish, then please get in touch! I have several ongoing projects also on these fabulous fishies.

Always excited to see these adorable fish at the Melbourne Museum

Parlez-vous français?

Nope, me neither! I speak some very rusty Japanese and a little Swedish, but can not claim to “parle français” myself. Despite this, I was a co-author on a French language article published last week by the journal Médecine/Sciences.

The article, L’origine phylogénétique des doigts, can be translated as “The phylogenetic origin of fingers”, and covers our work on the fish with fingers, Elpistostege. Our first article was published in Nature earlier this year, and you can read my original blog post about it too.

This new article was co-authored with Prof. Richard Cloutier and Prof. John Long and details our discovery of the first occurrence of digits in a fish, even though the pectoral fin of Elpistostege still retains primitive features, such as the presence of rays. The specimen is just the fourth Elpistostege fossil known. It was discovered by Richard and his team in 2010 in Miguasha, Quebec, Canada, and is about 375 million years old.

So if you’re a Francophile, Gallophile, or just love fish fingers, get reading about good ol’ Elpistostege!

Artist’s impression of Elpistostege by the very talented Chase Stone, image originally published in Scientific American

*** EDIT: more Elpi! This week a popular science article (in English) was published by The Science Breaker, a website that publish short lay-summaries (“breaks“) of scientific research. Our article “Elpistostege: a fish with legs or a tetrapod with fins?“, was again written by Richard, John and myself.

Alice, John and Richard in Adelaide during 2019

A million times brighter than the sun?

Have you heard of something called a synchrotron? Did you know they can produce light more than a million times brighter than the sun? Did you know we have one here in Australia?

A synchrotron is a very large machine – so large it needs its own purpose built building (about the size of a footy oval) to house it! It accelerates electrons around a ring super, super fast (almost to the speed of light) before shooting them off down “beamlines” to produce extremely powerful light. (Sharks with freaking laser beams, anyone?)

In my research I harness this powerful light like a supercharged X-ray machine to look inside ancient fossils. I’ve used the synchrotron in Melbourne, run by the Australian Nuclear Science and Technology Organisation (ANSTO) a few times now, as well as ESRF in Grenoble, France.

This machine creates a series of scans (tomograms) of an object based on the density of the various materials contained within (this is similar but distinct from neutron tomography). We can then create a 3D dataset from the resultant stack of images, and make 3D computer models from these scans for use in our research to look inside bone, virtually reconstruct a skeleton or run biomechanical analyses, for example.

Together with some of my colleagues, including visiting researcher Dr Tom Challands, I was due to visit the synchrotron in April this year. However, we all know COVID wreaked havoc with all the best laid plans… so our beamtime had been rescheduled for December… but alas, we were still not allowed to travel interstate to attend our experiment!

Thankfully, an incredibly generous colleague and collaborator, Dr Joseph Bevitt, came to our rescue. He drove one of our specimens from Sydney to Melbourne, collected some specimens on loan from the Melbourne Museum, and then scanned our material for us with the ANSTO beamline scientist, Anton Maksimenko.

Dr Joseph Bevitt at the Australian Synchrotron (Dec 2020)

Access to the ANSTO beamtime is absolutely invaluable for my research. It’s incredibly exciting to be able to use its state-of-the-art scanning technology to look inside rare and ancient fossils that are hundreds of millions of years old. I can’t wait to see the results from the scans made during this most recent visit…. watch this space!

Brains ‘primed’ for life on land

There’s been a small flurry of media activity this week about our recent paper on the brains and jaw muscles of some salamanders and lobe-finned fish (my favourites, remember). The original paper was published by the journal Royal Society Open Science and co-authored by myself with Tom Challands (University of Edinburgh) and Jason Pardo (University of Calgary).

The paper, “Mandibular musculature constrains brain–endocast disparity between sarcopterygians”, looked at the size and shape of the brains in the axolotl (Ambystoma), the fire belly newt (Cynops), lungfish (Neoceratodus and Protopterus) and the coelacanth (Latimeria).

We studied this to provide insight into what the brains of the first ‘tetrapods’ (the first fish that crawled onto land millions of years ago are relatives of the lobe-finned fishes) might have looked like. Living lungfish and amphibians such as salamanders are the closest extant (living) relatives of those first fossil tetrapods.

We found that lungfish and salamanders have brains that are actually quite large and fill their skulls to a much higher degree compared to the coelacanth. Furthermore, it seems that there might be an interplay between the skull architecture and size of the jaw muscles and the overall size or “fullness” of the brain in these animals.

You can read more about it here from:

BLiSS*Adelaide 2020

Last week I “attended” another virtual conference, this time a Science & Innovation meeting held by EMCR’s for EMCR’s (Early/Mid-Career Researchers) with a strong focus on multidisciplinary collaboration across local institutions, called BLiSS*Adelaide.

The organisers did a great job pivoting and adapting to an online format, with sessions spread over four mornings throughout the week. This was some well-thought through scheduling to avoid Zoom-fatigue! The opening keynote was delivered by Dr Cathy Foley, Chief Scientist at CSIRO, and there was an engaging program of speakers each day as well as networking opportunities via “breakout rooms”.

Delegates were able to present their research via short 3-minute pre-recorded “Science Bites” and my contribution was called “Powerful Imaging Techniques for Palaeontology”. I am pleased to announce that I was awarded the Best Science Bites Presentation (People’s Choice – Lights, Camera, Action!) at the BLiSS*Adelaide 2020 Virtual Conference!

Many thanks to all who voted for my presentation, and thanks to the organisers and sponsors of the event which enabled such a great event to go ahead.

SVP goes virtual

The Society of Vertebrate Paleontology (SVP) is an educational and scientific society that holds an annual meeting each year (you may remember my visit to SVP in Brisbane last year). The SVP conference is usually the largest collection (accumulation?) of vertebrate palaeontologists and was due to be held in Cincinnati this year for it’s 80th iteration. Alas, as we well know, 2020 has not gone to anyone’s plan and so for the first time in it’s history, SVP went fully virtual!

I was honoured to be invited to participate in a special symposium “Frontiers in Paleoneurology and Neurosensory Evolution” convened by Alan Turner & Amy Balanoff. My talk was entitled “Brain-braincase relationships across the fish-tetrapod transition” and provided me with a great opportunity to show some recent work myself and colleagues have been doing on the brains of living fish and salamanders, as well as some braincases of ~340-375 million year old tetrapod-like fossil fish.

For those “attending” the conference, you can access my presentation via this direct link.

The conference organisers have done an amazing job adapting to the virtual format and accommodating scientists from across the globe in almost every conceivable time zone. We were able to watch pre-recorded presentations in our own time, but then there were live Q&A sessions attached to each theme.

It’s been really wonderful to be able to participate in this meeting during a year when large gatherings and overseas travel seem but a distant memory, but sharing our work and speaking with other scientists remains vital for continued sharing of knowledge and the overall advancement of our field.