The gang tries to discuss two papers that look at the evolutionary impacts of the K-Pg mass extinction. Specifically, they look at one paper that estimates sampling probability throughout the late Cretaceous to determine if record bias influences our understanding of the extinction, and another paper that looks at species area relationships to investigate ecological shifts in response to the event. However, the gang gets completely lost and sidetracked throughout. They starting talking about the papers around 18 minutes in… and very quickly lose track again. It’s going to be one of those podcasts.

Up-Goer Five (Curt Edition):

The friends do a real bad job of talking about two papers that look at what happened when a big rock fell from the sky a long time ago. The first paper looks at the rocks we have from that time and tries to see how well we know what was happening and what was going on with the animals that were around at that time. Given the rocks we have, how sure are we that we know where animals were and how many of those things were around. It turns out that just before the big rock hit, we do not have a good idea of what things were around and where they were.

The second paper looks at how the places where things were living in the past changed before and after the big rock hit. The idea is that some animals may have done well because they could go to all of the places when things get bad because they do well when things go bad. This paper says that this is not happening and that there is way more going on with these groups that were doing well after the big rock hit.

References:

Close, Roger Adam, and Bouwe Rutger Reijenga. "Tetrapod species–area relationships across the Cretaceous–Paleogene mass extinction." Proceedings of the National Academy of Sciences 122.13 (2025): e2419052122.

Dean, Christopher D., et al. "The structure of the end-Cretaceous dinosaur fossil record in North America." Current Biology (2025).

The gang discusses two papers that look at the evolutionary impact of shifts in habitat occupation. The first paper looks at a clade of sharks moving into the depths, and the second paper investigates habitat shifts in mammals across the Cretaceous and Paleogene. Meanwhile, Amanda has some opinions, James is doing much better, and Curt is easy to amuse.

Up-Goer Five (Curt Edition):

The friends talk about two papers that look into how animals change when they move from one type of place to another. The first paper looks at animals with big teeth that has soft parts inside and live in the water. One group of these animals is found in really deep water today, but in the past they were found in water that is not deep. This paper looks at when this move into the deep happened, and what it happened along with.

The second paper looks at parts of animals that have hair and how these parts have changed over time. These parts are used for moving around and so they can let us know how these animals were moving in the past. This paper shows that before a really bad thing happened, a lot of these animals were moving in the trees, but after that big thing happened these animals were moving in a lot more different ways with more on the ground.

References:

Marion, Alexis FP, Fabien L. Condamine, and Guillaume Guinot. "Bioluminescence and repeated deep-sea colonization shaped the diversification and body size evolution of squaliform sharks." Proceedings B 292.2042 (2025): 20242932.

Janis, Christine M., et al. "Down to earth: therian mammals became more terrestrial towards the end of the Cretaceous." Palaeontology 68.2 (2025): e70004.

The gang discusses two papers that use morphometrics to investigate patterns of selection on bird morphology. The first paper looks at the morphology of feathers, while the second paper looks more broadly at various parts of the avian body. Meanwhile, James breathes new life into a classic, Amanda is passionate about formatting, and Curt exposes “the truth”.

Up-Goer Five (Curt Edition):

The friends talk about two papers that look at animals that move in the air. Both of these papers look at how these animals look and try to find out why these animals look the way they do. The first paper looks at the different types of soft things that these animals use to fly and also to stay warm. They look at how these soft things look and how that look has changed over time and between groups. Some of these animals that don't fly have soft things that are different from the ones that do fly, but they way they are different is different with each group that does not fly.

The second paper looks at parts of these animals like their mouths to see how they change between groups. They find that there are lots of things these animals could be doing that most of them are not doing. This makes them say that maybe there is something keeping the animals looking like that because if they change too much in one way it might be really really bad for them.

References:

Sayol, Ferran, et al. "Biophysical constraints on avian adaptation and diversification." BioRxiv (2023): 2023-10.

Saitta, Evan T., et al. "Feather evolution following flight loss in crown group birds: relaxed selection and developmental constraints." Evolution (2025): qpaf020.

The gang discusses two papers that look at preserved skin/external tissues. The first paper shows a unique record of Cambrian molting, and the second paper looks at the first preserved samples of plesiosaur skin. Meanwhile, Amanda commits an "own goal”, Curt shares some old internet fun, and James has opinions about fins.

Up-Goer Five (Curt Edition):

The friends talk about two papers that look at skin that is very very very old. The first paper looks at animals from a long time ago that lose their skin when they get too big for it when then grow. They found these parts on the skin that are hard and most of the time there are two but some of them have four, and that these ones that have four are because they are growing new skin under the old skin.

The second paper looks at an animal from a long time ago that breathes air but lives in the water and is close to things today that have harder skin. Other animals like this animal have some skin that we know about, but for this group of animal we did not know a lot about their skin. In the other animals that move into water, their skin gets soft, but this group shows that some of their skin is hard like the animals that are on land. This might be because how these animals live.

References:

Yu, Chiyang, Deng Wang, and Jian Han. "Cambrian palaeoscolecidomorph Cricocosmia caught in the act of moulting." Historical Biology 37.3 (2025): 643-649.

Marx, Miguel, et al. "Skin, scales, and cells in a Jurassic plesiosaur." Current Biology (2025).

The gang discusses two papers that look into the evolution and timing of key morphological innovations within animal groups. The first paper describes possible raptorial appendages in fossil artiopods, and the second paper finds early evidence of modern bird morphologies in the Jurassic. Meanwhile, Amanda gloats, Curt dies, and James eulogizes.

Up-Goer Five (Amanda Edition):

Today our friends look at two papers where one friend can feel better about how they do the work than how other people do the work. One paper is about big face hand animals with many parts to their legs that use their big face hands to maybe grab and eat other animals. It says that maybe these animals with many parts to their legs all got the big face hand parts in different ways that other animals with many parts that also have the big face hand parts.

The other paper is about the animals that do not have hair or hard skin that fly. It says that the animals that do not have hair or hard skin that fly show up earlier than people maybe thought that they did. They are animals that are more like today's animals that do not have hair or hard skin that can fly. One of our friends has said this for a long time and felt good when they saw this paper.

References:

O'Flynn, Robert J., et al. "The early Cambrian Kuamaia lata, an artiopodan euarthropod with a raptorial frontal appendage." Journal of Paleontology (2025): 1-13.

Chen, Runsheng, et al. "Earliest short-tailed bird from the Late Jurassic of China." Nature 638.8050 (2025): 441-448.

The gang discusses two papers that look into the timing of evolution of the “crown group”. The first paper looks at fossil glass sponges, and the second paper looks at the phylogeny of lampreys. Meanwhile, James gives some sound advice, Amanda has ambitious hobby plans, and Curt imagines the perfect media crossover.

Up-Goer Five: (Curt Edition)

The friends talk about two papers that look at groups of animals and try to see when the things that we see today in these groups may have first happened in the past and what we can tell us about why those things might have happened. The first paper looks at a group of animals that are made up of many single parts that can all act on their own and these animals get food out of water in a very simple way. This paper finds some very old animals that look a lot like some groups of these animals we see today. This would mean that this group may have been around a lot longer ago than we think.

The second paper looks at a group of animals that are long without much going on and a round mouth and live in the water. This group has animals that live in different places that have made people ask why. This paper looks at how all of these animals changed over time and uses that to see when the animals that we see today may have first been around. They find that these animals may have first appeared during a time that was really hot, and that might be why the animals are where they are today.

References:

Botting, Joseph P., et al. "Advanced crown‐group Rossellidae (Porifera: Hexactinellida) resembling extant taxa from the Hirnantian (Late Ordovician) Anji Biota." Papers in Palaeontology 11.1 (2025): e70000.

Hughes, Lily C., et al. "Phylogenomic resolution of lampreys reveals the recent evolution of an ancient vertebrate lineage." Proceedings B 292.2038 (2025): 20242101.

The gang celebrates the research of the late Elisabeth Vrba by talking about two of her papers, as well as her research more broadly. And, despite their best efforts, they get easily distracted on tangentially related side discussions.

Up-Goer Five (Curt Edition):

The friends talk about two papers from someone who they want to remember the memory of because that person is no longer with us. They talk a lot about this person's work, and some other things that come up as they are talking. The big things these two papers look at are how small things working together can build things that are bigger than themselves, and how those bigger things can be changed by the small things but not in a way where the big things can be known just by looking at the small things. The big things have stuff in them that come up from the way the small things work together to build something bigger than themselves.

References:

Vrba, Elisabeth S. "Macroevolutionary trends: new perspectives on the roles of adaptation and incidental effect." Science 221.4608 (1983): 387-389.

Vrba, Elisabeth S. "Mammals as a key to evolutionary theory." Journal of mammalogy 73.1 (1992): 1-28.

The gang discusses two papers that look at some exceptional soft-tissue preservation during the Silurian. The first paper potentially identifies a unique type of pterobranch, and the second paper looks at some early molluscs. Meanwhile, James has seen some movies, Amanda has a skibidi day, and Curt’s soul dies.

Up-Goer Five (Curt Edition):

The friends talk about two animals from a long time ago that are only found as soft parts and that makes it hard to find the parts of them that were in the ground a long long time ago. The first paper looks at an animal that is not well known in the past but is close to another animal that is better known. These soft parts are weird and people did not know what they were for a long while. This paper makes the case for this being one of this group of animals that all live in long empty round things together. They also say that this one may have lived moving in the water even though the ones today all sit at the bottom of the water on the ground.

The second paper looks at another group of animals that many today have a hard part on them and some of them turn their body when they grow. The animals that they are looking at do not do these things. They have hair and are long. These are animals are from a group that we think might be close to what the early animals in this group today would have looked like. The friends talk about this paper because they gave the animals funny names.

References:

Briggs, Derek EG, and Nicolás Mongiardino Koch. "A Silurian pseudocolonial pterobranch." Current Biology 33.23 (2023): 5225-5232.

Sutton, Mark D., et al. "New Silurian aculiferan fossils reveal complex early history of Mollusca." Nature (2025): 1-6.

The gang discusses two papers that look at some exceptionally preserved juvenile fossil specimens and the interesting clues these fossils give to the ontogeny of extinct groups. The first paper is the current oldest preserved tadpole, and the second paper is an exceptionally preserved mummified sabre-toothed cat. Meanwhile, Amanda becomes light, James is visited, and Curt is left in the dust and the filth.

Content warning: This episode contains covers some potentially dark material given that these fossils are juveniles. The following time stamps represent some of the more sensitive moments in which the group make morbid jokes about the subject matter.

6 min 3 sec to 6 min 39 secs.

58 min 13 seconds to 58 min 29 secs

Up-Goer Five (Curt Edition):

The friends talk about two papers that show some kids from animals groups that are no longer around. These papers are cool because they show how animals from a long time ago changed as they got older. The first paper looks at the kid of an animal group that changes a lot from a thing that moves through water to a thing that jumps on the ground. This kid is somewhere in the middle of jumping and moving through water. This is the oldest of this type of kid we have found so far. The group today is different because they go through this really big change. This paper shows that they were going through this really big change a long long time ago and shows that this change probably happened early on in their time line.

The second paper looks at a kid that is from a group of animals with hair and long teeth. This kid was in ice and so we have a lot of things that we would not get that are soft. This is the first time we have seen the soft parts for this age of this animal and it shows us that lots of things we see in the grown animals were also there when they were kids.

References:

Chuliver, Mariana, et al. "The oldest tadpole reveals evolutionary stability of the anuran life cycle." Nature (2024): 1-5.

Lopatin, A. V., et al. "Mummy of a juvenile sabre-toothed cat Homotherium latidens from the Upper Pleistocene of Siberia." Scientific Reports 14.1 (2024): 28016.

The gang discusses two papers that look at the evolution of photosynthesis in different groups. The first paper looks at what might be the first fossil evidence of thylakoids, and the second paper finds evidence for photosynthesizing symbiotes in Devonian fossil corals. Meanwhile, Amanda is making a lasagna, James has a lot of opinions about lasagna (~10 minutes until we actually get to the paper), and Curt is all about those sponges.

Up-Goer Five (Curt Edition):

The friends talk about two papers that look at how some types of living things can make food from the sun. The first paper looks at these very very old things that are very very very small. Inside these things they find very very very small parts of things that are used today by some living things to help make food from the sun. This might be the oldest one of these things that we have ever found, and it makes it so that we can see how things might have gotten better at making food from the sun over time.

The second paper looks at old animals that live in the big blue wet thing that all live close together and make big hard parts that make walls in the water. These old animals are like the ones we see today but they are a group that is not around anymore. Groups today have friends that help make food from the sun for them. This paper looks to see if the old animals had those friends (or friends like them) too. They find that animals today keep some bits of things they do not usually want so that their friends can eat them. This can be seen in the hard parts they make. When they looked at the hard parts of the old group of animals, they saw that they were doing this too. This means that these animals were keeping food for friends just like that animals we see today.

References:

Demoulin, Catherine F., et al. "Oldest thylakoids in fossil cells directly evidence oxygenic photosynthesis." Nature 625.7995 (2024): 529-534.

Jung, Jonathan, et al. "Coral photosymbiosis on Mid-Devonian reefs." Nature (2024): 1-7.