The Fossil Files

How and when did mammals transition from laying eggs to live birth? The fossil record doesn't typically preserve soft tissues like embryos and placentas making this a tough problem. This week we take a look at two new fossil discoveries that begin to answer the question of mammal evolution, and challenge orthodoxy. A cute baby dicynodont fossil from the Triassic of South Africa is the first mammal to be captured 'in ovo' i.e. inside its egg. Secondly, we discuss a new fossil cynodont from the Triassic of Argentina that might have recorded its growth and birth in its bone histology. Using this we begin to piece together our own evolutionary history and estimate when placental mammals 'got cracking'. Along we way we ask if viviparity evolved twice and whether teenagers can be trusted to go to the shops to get eggs.

The papers discussed this week are "The first non-mammalian synapsid embryo from the Triassic of South Africa" by Julien Benoit and colleagues published in PLoS One in April 2026 https://doi.org/10.1371/journal.pone.0345016 and "Early origin of viviparity in the mammalian lineage" by Leandro Carlos Gaetano and colleagues published in Frontiers in Mammal Science https://doi.org/10.3389/fmamm.2026.1845319

Palaeoart by Sophie Vrard.

New finds in palaeontology are dependent on people getting out in the field and digging up fossils, but are the next generation of palaeontologists getting to do that? Opportunities for fieldwork and fieldwork training have become more expensive, which means students might not be getting the training they need. What happens next? In this week's bonus episode, Susie and Rob discuss the importance of fieldwork and whether the next generation of palaeontologists are facing 'an extinction of experience'. We focus on the views of students and early career researchers and ponder what happens to palaeontology if we focus on large scale studies of existing data to the exclusion of digging up new stuff. This is a preview of the full episode available to our Patreon members https://www.patreon.com/cw/FossilFiles

The main paper discuss in this episode is "#Yourpalaeolife: Interrogating the Status of Fieldwork Among Early Career Palaeontology Researchers" by Harriett Nuttall published in Ecology and Evolution in July 2026 https://doi.org/10.1002/ece3.74032

We need your support to be able to continue creating The Fossil Files. To get access to exclusive bonus episodes, you can find us on Patreon https://www.patreon.com/cw/FossilFiles

Sounds play such an important ecological role, but palaeontologists have always had to use their imagination when reconstructing the sound of extinct landscapes: Until now! For the first time a team of scientists have reconstructed the sound of a whole palaeo-community. Using fossil insect wings and some technological approaches to modern animals, the team were able to use physics and AI models to reconstruct the acoustic landscape of a Jurassic forest peppered with the calls of insects. Were the animals avoiding predators or just talking to each other? Listen in and find out.

This week's paper is "Reconstruction of an extinct soundscape reveals ultrasonic communication in the Jurassic" by Jun-Jie Gu, Fernando Montealegre-Zapata and colleagues published in Proceedings of the National Academy of Sciences in August 2026 https://doi.org/10.1073/pnas.2615107123

We also provide some updates from previous episodes: #5 "Were Neanderthals the first fossil collectors" updated with Roman findings https://doi.org/10.1017/S0068113X26100749 #30 "How can we reconstruct the smell of extinct organisms" smells different using new data from fishes https://doi.org/10.1098/rspb.2025.3277 #25 "A dinosaur covered in porcupine spines & the earliest fossil cloaca" gets a new friend with the discovery of an early mammal cloaca https://doi.org/10.1016/j.isci.2026.116752 And the most controversial of all #4 "Is de-extinction a scam?", well it looks more likely given what got left out when the paper finally came out https://doi.org/10.1016/j.xgen.2026.101306

Widescreen art by Zuo Xiaoran

The origin of turtles has long been a scientific mystery. Not only do they have super weird things going on with their ribs, head, and teeth, but also its unclear if they were more closely related to birds and crocodiles, or snakes and lizards, or something else. This week we take a deep dive into the origin of turtles, terrapins and tortoises, and the process of "turtleization". New data from the important Permian critter Eunotosaurus of South Africa might have now solved that problem of the question: Where did turtles come from?

This weeks's paper is "The phylogenetic origin of turtles" by Xavier Jenkins and colleagues published in Current Biology in June 2026 https://doi.org/10.1016/j.cub.2026.04.070

Wide screen art by Gabriel Ugeuto.

What happens when fossils that have been faked or 'enhanced' end up being used in scientific studies? Why does it happen? How can we spot them? How do researchers, preparators, publishers and museums deal with it? In this bonus episode Susie and Rob take a look at three nightmarish examples of faked fossils that ended up in the scientific literature, and what happened after they were spotted. Our first story is the discovery that the exceptional soft tissues of a famous Permian reptile had actually been painted on, the second of a dinosaur that had been stitched together from multiple fossils that ended up being far more interesting than the fake, and finally a cheetah that was stitched together from fossil, plastic, and plaster, yet still got published.

This is a preview of our bonus episode. The full episode is available on our Patreon along with lots of other bonus content https://www.patreon.com/cw/FossilFiles

The papers and sources discussed this week are:

"Forged soft tissues revealed in the oldest fossil reptile from the early Permian of the Alps" by Valentina Rossi and colleagues published in Palaeontology in February 2024 https://doi.org/10.1111/pala.12690

"The Archaeoraptor forgery" by Timothy Rowe and colleagues published in Nature in 2001 https://doi.org/10.1038/35069145 with additional information from Benjamin Gutierrez https://www.prehistoric-wildlife.com/archaeoraptor/

"A primitive Late Pliocene cheetah, and evolution of the cheetah lineage" by Per Christiansen and Ji Mazák published in PNAS in 2009, retracted 2012 https://doi.org/10.1073/pnas.0810435106 with important extra research and context from Retraction Watch https://retractionwatch.com/2012/08/20/author-retracts-pnas-about-alleged-pliocine-cheetah-fossil-that-had-been-questioned/

As well as tasting good, fruit play a really important role in ecosystems across the world. But when did they evolve? Were dinosaurs eating them and dispersing them? In a fossil files first, we take a look at the evolution of plants, in particular the centuries long mystery of how and when the flowering plants (angiosperms) got going. A newly described site in New Mexico yields large and varied fleshy fossil fruits which upend how we think about Cretaceous ecosystems. The fossil fruits and seeds are orders of magnitude bigger than other Cretaceous fruit, indicating an active role of animals in their consumption and dispersal in complex forest environments. We also take a look at the story from pollen to reconstruct how and when angiosperms diversified, potentially in two pulses in the Cretaceous and after the Cretaceous. Plant Power!

The papers we look at this week are "Diversification of angiosperm reproductive strategies predated the end-Cretaceous extinction" by Jiamen Lee from Berkley and colleagues published Science in June 2026 https://doi.org/10.1126/science.adw9457, "Pulsed evolution shaped extant angiosperm pollen disparity" by Yang Luo from Kunming and colleagues published in Nature Communications in January 2026 https://doi.org/10.1038/s41467-025-68253-8, and "Integrated analysis of fossils and molecular divergence time estimates a latest Jurassic origin of angiosperms" by Ruolin Wu from Bristol and colleagues published in Nature Plants in June 2026 https://doi.org/10.1038/s41477-026-02311-x

Wide screen art by Brian Engh.

You can support The Fossil Files and access bonus via our Patreon https://www.patreon.com/cw/FossilFiles

The deep sea environment holds many mysteries but yields hardly any fossils. A new mindblowing finding at the bottom of the Indian ocean challenges the way we think about life in the deep and the nature of palaeontology. In 2023, a Chinese submersible exploring a 6km deep trench found 476 fossil cetaceans. These extinct whale fossils were covered with life forms previously unknown to science, and what's more, the fossils ranged in age from recent to 5 million years old. How did they get there? Why so many? Can fossils really accumulate in the same place for 5 million years, and just…. sit there?

This week's paper is "A 5.3-million-year-old deep-sea whale necropolis in the Diamantina Zone" by Xiaotong Peng and colleagues, published in Nature in June 2026 https://doi.org/10.1038/s41586-026-10546-z

Wide screen includes picture from Global Trend.

Studying for a PhD is in an important step towards becoming a scientist, but the process of finding and applying for a PhD programme is mysterious and inaccessible. In this bonus episode Susie and Rob discuss some tips and ideas to demystify the process. Is a PhD right for you? How do you find the right supervisor and project? What are universities looking for in your application? What questions are you going to face in the interview? This a preview of our bonus episode, the full episode can be found on our Patreon. For further related content, check out our episode "How to become palaeontologist" (#26).

Where, when, and how did the animals first appear? The fossil record holds some tantalising insights from well-preserved sites in Canada, Australia, Russia (and Leicester). This week we are joined by Dr Emily Mitchell of the University of Cambridge to discuss how to find these fascinating Ediacaran fossils, what they mean, and how they evolved. Did they move? Were they left-handed? Did they have sex? Where are they hiding? This is a story that includes lasers, school children, lichens, and bees.

The papers discussed this week are "Earliest evidence of behavioural handedness in the Ediacaran motile bilaterian Spriggina floundersi" by Scott Evans and colleagues published in Science Reports in July 2026 https://doi.org/10.1038/s41598-026-53857-x, and "Discovery of White Sea assemblage fossils from Laurentia" by Scott Evans and colleagues published in Science Advances in May 2026 https://doi.org/10.1126/sciadv.aed9916

We also continue of our discussion of last episodes's paper, "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 in June 2026 https://doi.org/10.1038/s41559-026-03094-2

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.