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.

Life nearly died 252 million years ago in a mass extinction at the end of the Permian. It was long thought that it took 10s of millions of years into the Triassic for life to recover and get back to a 'new normal'. That was until a new and very muddy fossil site from the high Arctic revealed a staggering diversity of predators and tetrapods in the earliest Triassic seas. This week we take a look at the new findings and its implications for life's ability to recover from major extinctions.

This week's paper is "Earliest oceanic tetrapod ecosystem reveals rapid complexification of Triassic marine communities" by Aubrey Roberts, published in Science in November 2025 DOI: 10.1126/science.adx739

An accessible summary can be found here.

You can see lots of nice pictures and get some extra context from some slides by Jørn Hurum here

Wide screen art by Robert Back.

Lead is a well known pollutant affecting human health over the course of our urbanisation and industrialisation. But what about before this? Analysis of a range of fossil hominid teeth from the Pleistocene reveals that lead poisoning might have been a ubiquitious part of our deep evolutionary history. Furthermore, lab experiments looking at the effect of lead exposure on human and neanderthal brain development reveals the interplay between this pollutant and 'the language gene' (FOXP2). Together, this suggests that the development of language, socialisation and ultimate evolutionary success of humans might be related to our ability to overcome lead poisoning.

This week's paper is "Impact of intermittent lead exposure on hominid brain evolution" by Renaud Joannes-Boyau and colleagues published in Science Advances, October 2025. https://doi.org/10.1126/sciadv.adr1524

Wide screen art by Mark Witton

Having large body sizes conferred all sorts of advantages on dinosaurs, but it potentially made breeding a bit complicated. This week we take a look at some weird pathologies in fossil hadrosaurs (duck billed dinosaurs and friends) and what they might tell us about their amourous habits - do broken backs provide evidence of rough housing in the bedroom?

This week's paper is "Deciphering causes and behaviors: A recurrent pattern of tail injuries in hadrosaurid dinosaurs" by Filippo Bertozzo and colleagues, published in IScience November 2025 https://doi.org/10.1016/j.isci.2025.113739

The widescreen artwork is by Troco.

Part 2: Around 66 million years ago an enormous asteroid barrelled into the earth and wiped out ichthyosaurs, pterosaurs, and dinosaurs*. Debate has raged back and forth as to whether the dinosaurs were already in decline before this mass extinction or were still going strong. This week, Susie and Rob are joined by Prof. Steve Brusatte to take a look at what vertebrates were doing just before the asteroid hit. In part 2 we discuss what would have happened if the asteroid had missed, Steve's new upcoming book, Jurassic World, and Nannotyrannus.

*except birds of course.

Widescreen artwork by Natalia Jagielska

Around 66 million years ago an enormous asteroid barreled into the earth and wiped out icthyosaurs, pterosaurs, and dinosaurs*. Debate has raged back and forth as to whether the dinosaurs were already in decline before this mass extinction or were still going strong. This week, Susie and Rob are joined by Prof. Steve Brusatte to take a look at what vertebrates were doing just before the asteroid hit. We discuss his new paper on fossil vertebrates from New Mexico, its implications for scenarios of dinosaur evolution and extinction, and what is life is like for a working palaeontologist, digging up Cretaceous fossils.

This week's paper is "Late-surviving New Mexican dinosaurs illuminate high end-Cretaceous diversity and provinciality" by Andrew Flynn, Steve Brusatte and colleagues, published in Science in October 2025. https://doi.org/10.1126/science.adw3282

*except birds of course.

Widescreen artwork by Natalia Jagielska

Artificial Intelligence seems to be changing everything, everywhere, all at once. But how will the science of studying the very old be transformed by the technology of the new? In this episode Susie and Rob take a look at the risks and opportunities for palaeontology with the application of AI: palAIontology. Can we use AI to find, identify, and classify fossils?

The paper's discussed this week are: "Artificial intelligence in paleontology" by Congyu Yu and colleagues published in Earth Science Reviews May 2024 https://doi.org/10.1016/j.earscirev.2024.104765 and "Early humans and the balance of power: Homo habilis as prey" by Marina Vegara-Riquelme and colleagues published in Annals of the New York Academy of Sciences in September 2025 https://doi.org/10.1111/nyas.15321

In the last of our series from the massive Society of Vertebrate Paleontology meeting, Susie and Rob finally manage to catch up for a gossip. In this episode with get a disgusting taste of rotting crocodile experiments with Stephanie Drumheller of the University of Tennessee, an insight into the Dinosaur battle bus education project that has been travelling the Mongolian steppe with Bolor Minjin of the American Museum of Natural History and the Institute for the Study of Mongolian Dinosaurs, and finally how engineering approaches can help us figure out what fossil organisms were up to long after their death with Emily Rayfield, University of Bristol.

New fossil discoveries keep coming thick and fast, but we managed to sit down with the researchers as they present them. In this episode Susie and Rob catch up (in person!) on their second day in Birmingham and talk to the researchers tackling important transitions in vertebrate evolution: the transitions of moving onto land, into the sea, into the air. This includes Emily Hillan of University of Chicago and her discovery of a new specimen of the walking fish (?) Tiktaalik, Dave Hone of Queen Mary University London on his new research on pterosaurs and spinosaurs, Dean Lomax about his new research on ichthyosaurs and his latest book, and Luke Muscutt of Imperial on his swimming plesiosaur robot.