The idea that dinosaurs were all scaley beasts got a massive challenge in 2000s when a variety of feather-like structures were found in fossils in China and other places. An even greater diversity of weird coverings have been found since then, most recently an iguanodontian covered in spines. This week we take a look at the porcupine looking Haolong dongi and what this means for dinosaur evolution. We also take a look some amazing trace fossils from the Permian of Germany, so detailed they even show the scales of an early reptile, including its cloaca. That's right, an improbable fossil butthole. Two tales of suprising scales.

This week's papers are "Cellular-level preservation of cutaneous spikes in an Early Cretaceous iguanodontian dinosaur" by Jiandong Huang and colleagues published in Nature Ecology & Evolution in February 2026 https://doi.org/10.1038/s41559-025-02960-9 and "The earliest reptile body impressions with scaly skin" by Lorenzo Marchetti and colleagues published in Current Biology in March 2026.

Wide screen artwork by Fabio Manucci.

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.