The Fossil Files

The first animals turned up in the Ediacaran as simple frond-like organisms that didn't do much of anything. Why was this Pre-Cambrian 'Avalonian biota' so static and boring for 12-20 million years before animals started diversifying, moving and becoming more complex? This week we look at a new paper that reconstructs the ecology of the early Avalonian biota, in particular their sexual and and asexual reproductions strategies. To try and figure out what kind of sex these organisms were (or weren't) having, we need to do turn to some interesting maths based on their locations of the fossil surface. This unlocks all sorts of interesting evolutionary dynamics, potentially explaining how animals started to diversify after increasing sexual reproduction and competition in an increasingly dynamic and changeable environment. Life needed chaos! (and sex).
This week's paper is "The influence of reproductive mode on resource competition and diversity patterns in Ediacaran early animal communities" by Emily Mitchell and Andrea Manica published in Nature Ecology and Evolution, published June 2026 https://doi.org/10.1038/s41559-026-03094-2
We also mention another paper by Scott Evans (https://www.science.org/doi/10.1126/sciadv.aed9916) and the story of the discovery of the Ediacaran fossils in Charnwood fossil https://en.wikipedia.org/wiki/Tina_Negus
Wide screen art by Hugo Salais.

Tyrannosaurus rex is perhaps the most famous dinosaur and maybe even the most famous fossil animal. It has long been a source of curiosity as to why is has such small arms though. What could the possible function be? This week we take a look at a new paper has taken a quantitative approach to this age long-thorny problem to investigate the evolutionary changes that might have led to such unusual anatomy. Indeed it happened not just one, but five times in the theropods. Let's find out why and how!
 
This week's paper is "Drivers and mechanisms of convergent forelimb reduction in non-avian theropod dinosaurs" by Charlie Scherer and colleagues published in Proceedings of the Royal Society in May 2026. https://doi.org/10.1098/rspb.2026.0528

Wide screen art by Arvalis/Saurian.

Digging up dinosaur fossils is a complicated and unpredictable business. But how does it feel to be one of the scientists on the ground doing the exploring? What can you do when you are in a race to find dinosaur fossils before they are extracted and lost to the black market? In this episode Susie is in the field in Morocco to report the trials and tribulations of the team's dino hunting seasons. She takes us on a journey from exciting new dinosaur finds, disappointing setbacks when their quarry was raided, and their work with the local and national authorities to get the site protected for future generations. This is a preview of one of our bonus episode, the full version of which is available on our patreon for subscribers https://www.patreon.com/cw/FossilFiles
In this episode we hear from the team which includes Ahmed Oussou and Kawtar Ech-Charay of Sidi Mohamed Ben Abdellah University Fez, Richard Butler from the University of Birmingham, and Simon Wills and Pim Kaskes from the Natural History Museum London. 
You can find out more about Susie's work in episode 9, "The Spicomellus special".

The Fossil Files is one year old! Thank you everbody for your support! To mark the occasion, Susie and Rob take a look back at the last year and put together some of their favourite moments to highlight the best of The Fossil Files (so far)
The episodes covered are:
Episode 10. Fossil Fails: A Precambrian beehive and dinosaurs on the moon (September)
Episode 3. Is de-extinction a scam? (July)
Episode 6. Where did Pterosaurs come from? (August)
Episode 12. Cretaceous zombie ants (October)
Episode 9. The Spicomellis special (September)
Episode 5. Were Neanderthals the first fossil collectors? (July) 
Episode 19. Dinosaurs were doing fine (before the asteroid), with Steve Brusatte (December) 
Episode 17. AI & the future of palaeontology (December) 
Episode 2. Dinosaur poos from Poland (June)
Episode 20. Back-breaking and baby making, the disturbing bedroom habits of hadrosaurs (January) 
Episode 28. How to get a Species of Human Named after you (March) 
Episode 32. Were giant super intelligent octopuses the top predators of the Cretaceous? (May)

400 million years ago, before the rise of forests, the land was covered in mossy carpets, loomed over by weird 8 meter tall columns called Prototaxites. These weird giants have long been thought to be some sort of fungus body, slowly digesting rotting matter. A new paper has taken a detailed look at some well preserved fossils from the Devonian of Scotland and reveals that this enigmatic giant wasn't a fungus, wasn't a plant, wasn't an animal, and wasn't a bacterium... it was something else. This week Susie and Rob take a look at the strange world of the Devonian giant Prototaxites and speculate what it might, or might not, have been. In other fungus news, we also take a look at a paper using fungal microfossils to suggests that dinosaur extinction could have been a multi-phase event, before and after the asteroid impact at the end of the Cretaceous.
The main paper discussed this week is "Prototaxites fossils are structurally and chemically distinct from extinct and extant Fungi" by Corentin Loron and colleagues from the University of Edinburgh, published in Science Advances in January 2026 https://doi.org/10.1126/sciadv.aec6277
The other paper is "Fungal proliferation before and after the Cretaceous–Paleogene mass extinction event in North America" by Rosanna Baker and colleagues published in PNAS in May 2026 Fungal proliferation before and after the Cretaceous–Paleogene mass extinction event in North America https://doi.org/10.1073/pnas.2536899123
Wide screen art by M Humpage