The Fossil Files – Details, episodes & analysis

What (and when) is an animal? They are thought to have first arrived about 500 million years ago and immediately underwent an explosive diversifcation at the beginning of the Cambrian. When and how this important event took place has always been hard evolutionary problem to solve: fossils with the necessary preservation of soft-tissues are rare and limited. Two finds from China blow open new windows into this episode. 

The first is a new site from just before the Cambrian. It yields all sorts of typical Ediacaran weirdos, but preserved in a way that we don't usually get to see them. This not only sheds new light on what was going on before the Cambrian, but also means we can begin to look at the origin of animals in a new way.

The second is a new site from 27 million years after Cambrian began. The quality and diversity of the new fossil finds is massive, so much so that it could be considered a new "Burgess Shale", the archetypal and famous Cambrian deposit with exceptional preservation. 

In a final after-thought, we take a look at sponges and their evolutionary relationships. A new phylogeny helps us to understand why we have such a limited fossil record of early animals: they were likely completely squishy and devoid of a skeleton. 

Together a more complete picture of our distant animal origins is emerging and how palaeontology can help us, even through the limited windows that we have. 

The first paper is "The terminal Ediacaran Tongshan Lagerstätte from South China" by Jin-bo Hou and colleagues published in Nature Ecology and Evolution in November 2025. https://doi.org/10.1038/s41467-025-65176-2

The second paper is "A Cambrian soft-bodied biota after the first Phanerozoic mass extinction" by Han Zeng and colleagues published in Nature in Janaury 2026 https://doi.org/10.1038/s41586-025-10030-0

The final paper is "Independent origins of spicules reconcile paleontological and molecular evidence of sponge evolutionary history" by Maria Eleonora Rossi and colleagues published in Science Advances in January 2026 DOI: 10.1126/sciadv.adx1754

Wide screen art by Dinghua Yang.

Sometimes the answer to palaeontological mysteries can actually be right in front of our faces, if only we know how, or where, to look. This week we take a look a two cases by the Fossils Files' own Susie, Rob and Jane. Firstly, we reveal how the eyes and skeletons of early vertebrates were right in front of us, hidden in Silurian Scottish fish fossils, but only observable when we applied high powered X-ray analysis to them. Secondly, we look at the mystery of the missing European ceratopsian dinosaurs. Turns out these horned dinosaurs were there all along after a new discovery from the Cretaceous of Hungary shook up the family tree. 

So this week the Fossil Files gets a bit self-involved as we discuss about our own research. The first paper was by Jane Reeves (behind the scenes contributor to The Fossil Files), with Rob Sansom and colleauges in Manchester and California, published in Proceedings of the Royal Society B in January 2026 "Early vertebrate biomineralization and eye structure determined by synchrotron X-ray analyses of Silurian jawless fish" https://doi.org/10.1098/rspb.2025.2248

The second paper was by Susie Maidment, Richad Butler, Steve Brusatte, Luke Meade, and colleauges in Hungary, Germany and Romania published in Nature in January 2026 "A hidden diversity of ceratopsian dinosaurs in Late Cretaceous Europe" https://doi.org/10.1038/s41586-025-09897-w

Another paper we mention when talking about fossil fish came out the same week of Jane's paper in Nature by Xiangton Lei and colleagues published in Nature in January 2026 "Four camera-type eyes in the earliest vertebrates from the Cambrian Period" https://doi.org/10.1038/s41586-025-09966-0

Wide screen art by Matt Dempsey. 

The Fossils Files are on Tour! Susie and Rob are in Birmingham for the massive Society of Vertebrate Paleontology conference which has made a rare trip to Europe. We will be meeting and chatting with palaeontologists from all over the world and bringing you the latest discoveries and hot gossip. On day 1 we join the Nanotyrannus craze and chat to co-author of that study, James Napoli of Stoney Brook NY. The amazing "Duelling Dinos" specimen has been released the world by the North Carolina Museum of Natural Sciences and has sent dinosaur fans aflutter with its implications for tyrannosaurs. We also catch with Yara Haridy of the University of Chicago. She has been revealing lots of new insights into vertebrate origins and evolution with high powered synchrotron analyses. With also catch up Steve Brussatte of the University of Edinburgh as a preview of a longer episode coming up. 

For more information on Nanaotyrannus: https://naturalsciences.org/calendar/news/nanotyrannus-confirmed/

And for more information on vertebrate origins, check out our earlier episode "Our deep origins and the vertebrate that wasn't"

A newly discovered fossil from the Cretaceous of Mongolia tells us an interesting story about the purported head butting behaviour of dinosaurs. Pachycephalosaurs are famous for their thick domed heads but it has been disputed how or when this evolved. The beautifully preserved Zavacephale rinpoche has a well preserved skull and dome but also loads of details of the body and tail as well. What is suprising is that this individual is much smaller, and occurs much earlier, than other pachycephalosaurs. We take a look at this new fossil and what this means for interpreting the evolution of dinosaur behaviour. 

This week's paper is "A domed pachycephalosaur from the early Cretaceous of Mongolia" by Tsogtbaatar Chinzorig and colleagues from Mongolia and North Carolina, published in Nature in September 2025. https://doi.org/10.1038/s41586-025-09213-6

Wide screen palaeoart by Masaya Hattori.

Cordyceps is a weird fungus that can take over the brain of ants and spiders causing them to go zombie and commit suicide in order to spread disease. Weirder still, some new fossils from the Cretaceous have directly captured this nightmarish behaviour for the first time. We take a look at these interesting fossils, their potentially shady origin story, and their implications for reconstructing evolution of this unsual parasitic behaviour. Side-note: did fungus cause the extinction of dinosaurs?

The main paper discussed this week is by Yuhui Zhuang and colleagues "Cretaceous entomopathogenic fungi illuminate the early evolution of insect–fungal associations" published in Proceedings of the Royal Soceiy B in June 2025, (https://doi.org/10.1098/rspb.2025.0407), free version here.  

Discovery of the smallest ever dinosaur acheived quite a splash when it was publised on the front cover of Nature in 2020. The new critter, Oculodentavis, was the size of a hummingbird and reconstructed as close to Archaeopteryx on the lineage to birds. In this episode, Susie and Rob take a look at how this story quickly started to unravel as it turned out Oculodentavis might been something else altogether. This how episode also shed some light on a dark underbelly of an ethical problem for palaeontologists - what if your fossils are coming from a war zone and potentially funding ethic violence? 

The main paper discussed this week is by Lida Xing and Jingmai O'Connor and colleagues "Hummingbird-sized dinosaur from the Cretaceous period of Myanmar" published in Nature in 2020, now retracted (https://doi.org/10.1038/s41586-020-2068-4).

A brief accessible summary of what happened afterwards can be found here by Krister Smith in Current Biology "It's a bird, it's a plane, it's Oculudentavis!" (https://doi.org/10.1016/j.cub.2021.06.017).

A summary of the situation with Myanmar amber fossils including discussion of the paper by Emma Dunne and colleagues can be found in Science "Violent conflict in Myanmar linked to boom in fossil amber research, study claims" by Rodrigo Pérez Ortega (doi:10.1126/science.adf0973)

Wide screen palaeoart by Stephanie Abramowicz.

In the first of two episodes on notorious fossil fails, Rob and Susie take a look at how a serious case of mistaken identify unfolded for some Ediacaran 'fossils'. Herein lies a cautionary tail for all relating to pareidolia: our very human tendency to perceive patterns in random shapes and lines, or why we might see jesus is a piece of toast or a smiley face in a cut pepper. This takes us to unexpected destination for hunting for dinosaur fossils: the moon!

Image 1: A look at some 'Ediacaran fossils' from the Bhimbetka cave in India and some other structures found there.

Image 2: "Fossilised embryo of a dinosaur inside the egg on the moon". Yes you read that right.

The main papers discussed this week is by Greg Retallack and colleagues "Dickinsonia discovered in India and late Ediacaran biogeography" published in Gondwana Research in 2021 (https://doi.org/10.1016/j.gr.2020.11.008) with follow up articles by Joseph Meert and colleagues "Stinging News: 'Dickinsonia' discovered in the Upper Vindhyan of India not worth the buzz" published in Gondwana Research in 2023 (https://doi.org/10.1016/j.gr.2023.01.003) and SK Pandey and colleagues "Dickinsonia tenuis reported by Retallack et al. 2021 is not a fossil, instead an impression of an extant 'fallen beehive'" published in 2023 in the Journal of the Geological Society of India (https://doi.org/10.1007/s12594-023-2312-2).

The final paper is by Hari Mohan Saxena and Jagmohan Saxena "Dinosaur eggs with fossilized embryos on the moon" 'published' in the New York Science Journal (http://www.dx.doi.org/10.7537/marsnys160823.030).

Wide screen Ediacaran image by John Sibbeck.

Perhaps the weirdest dinosaur ever has just been described in Nature, by The Fossil Files' own Susie Maidment. In a worldwide EXCLUSIVE*, Susie gives as the unvarnshed truth about how this spikey Jurassic weirdo came to be found, what makes it different, and peek under the hood as to how palaeontological research like this is conducted. The story weaves in the local and scientific communities in Morroco, funding crises, a global pandemic, dodgy fossil collectors, international law, and a lot of hard work. 

The paper is "Extreme armour in the world's oldest ankylosaur" by Susannah Maidment and colleagues, published in Nature August 27th, 2025.

https://doi.org/10.1038/s41586-025-09453-6

*Not exclusive

Widescreen artwork: Matthew Dempsey

This new discovery is WEIRD. Mirasaura (the 'marvellous lizard') has been described from the Triassic of France, and it has mad projections coming out of its back, far longer than its body. We take a look at what these projections were, and were not (i.e. not feathers), their implications for the evolution of integumentary structures, and our own historically bad haircuts.

The paper is "Triassic diapsid shows early diversification of skin appendages in reptiles" by Stephan Spiekman and colleagues, published in Nature in July 2025.

https://doi.org/10.1038/s41586-025-09167-9

Wide screen art: Gabriel Ugueto

Squid are a really important part of marine ecosystems, but their fossil record is close to non-existent - their squishy bodies are just really unlikely to be fossilised. In this short bonus episode we take a new look at the squid fossil record. 'Digital fossil mining' reveals a massive diversity of squid in Creataceous oceans. How did the scientists do it and what does this mean?

The paper is "Origin and radiation of squids revealed by digital fossil-mining" by Shin Ikegami and colleagues of Hokkaido University, Japan. https://doi.org/10.1126/science.adu6248