Podcast 343 - GSA 2026

The gang discusses two papers that look into evidence of early innovations in sponge evolution. The first paper uses geochemical data to estimate the origin time of demosponges in the fossil record, and the second paper uses phylogenetic methods to map out spicule evolution in the history of sponges. Meanwhile, Amanda has good harvest, James catastrophizes, and Curt stirs the pot.   Up-Goer Five (Curt Edition): The friends look at two papers that look at a group of animals that pull in water inside them and people use their bodies to clean themselves and other things. These things have a lot of soft parts and the hard parts they do have were probably not around when this group first appeared. So the first paper is looking for changes in rocks that could be because these animals were around. Some of the changes have been shown could be caused by other kinds of living things that are not this group of animals, so the people on this paper did a lot of work using different things today to see if they could make stuff that could be found in rocks. They say that the stuff they have in rocks is coming from these animals and not the other things because of what they looked at. The second paper looks at how these groups of animals that pull in water are grouped together and uses that to see when they first appeared and also when they started making hard parts. They do not use the first paper in how they try to see when these animals first appeared. They show that the hard parts appeared a lot of times in the history of this animal group, and that main groups of these animals may have gotten their hard parts on their own, maybe many times.   References: Shawar, Lubna, et al. "Chemical characterization of C31 sterols from sponges and Neoproterozoic fossil sterane counterparts." Proceedings of the National Academy of Sciences 122.41 (2025): e2503009122. Rossi, Maria Eleonora, et al. "Independent origins of spicules reconcile paleontological and molecular evidence of sponge evolutionary history." Science advances 12.2 (2026): eadx1754.

We report back with coverage of the Geological Society of America 2026 annual meeting, and only once do we completely mess up using the equipment. Progress!

The gang discusses two papers that use a lot of statistics to make their arguments. The first paper looks at the argument against the existence of megalodon nurseries, and the second paper assesses the importance of biotic vs abiotic patterns in extinction. Meanwhile, James has a new button, Amanda has school spirit, Curt tries to be civil, and we all need a drink…   Up-Goer Five (Curt Edition): The friends look at two papers that use a lot of numbers to show if something may or may not have happened. The first paper looks at a big angry animal that lived in the sea and left behind a lot of really really big teeth. This big animal is thought to have had babies that lived in areas closer to the land. However, one paper came out and said that wasn't true and that the smaller ones were small because of the place where they lived made them not be able to get big. This paper looks at the other paper and says, no you are wrong, these ARE small because they are babies. This new paper runs the work the other paper did and shows that what they did was not right and that the work they did would show that these were babies. The second paper looks at groups of animals across time that died out and tries to see if the death of these animals was because of other animals or because of things that happened in the places that they lived. This paper does a lot of numbers and says that, of the changes in the world that they looked at, the death of these animals did not seem to happen when those changes happen, or at least not most of the time. They also say that when these animals start to die, other animals that they say are kind of like them do well. So they say that this means the animals that are doing well made the other animals die. The way that they picked the animals that are doing well is a bit funny, and they say that these are wide guesses. The friends have a lot to say about this paper.   References: Song, Haijun, et al. "Identifying biotic and abiotic roles in marine clade extinction." Nature Ecology & Evolution (2026): 1-14. Ferrón, Humberto G., et al. "No evidence for Bergmann's rule in Otodus megalodon." Papers in Palaeontology 12.4 (2026): e70106.

The gang discusses two papers that use comparative anatomy of bone to tell some really interesting stories about fossil animals. The first paper uses the hand bones of Stegasaurus and Camarasaurus to investigate how they walked and also the evolutionary processes by which they may have developed these unique shapes. The second paper pieces together the complex taphonomy of a dead ichthyosaur. Meanwhile, Amanda fails at giving directions, James fails and following directions, and Curt fails to keep any of this on track.   Up-Goer Five: (Curt Edition) The friends look at two papers that look at how you can learn cool things about how old animals lived by using their hard parts and seeing how those hard parts go together. The first paper looks at the hands of animals who are big and angry from a long time ago. This paper looks at two groups of animals that are not close to each other but both do things that look like each other for how their hands and feet work. This paper uses the hard parts of the hands and feet and uses how they fit together and how far they could move and bend and shows the most that they could move and bend to see how they would have walked. They find these two groups come at walking in a way that is the same but from different ways. The second paper looks at the parts of a thing that lived in the water and was around at the time of the big angry things. This animal shows that it had just eaten something, but also this animal looks like it was eaten itself. So, this animal ate something and then was eaten, and we can see this from the hard parts that are there and the ones that are not, as well as the bits of hard parts that are broken.   References: Senter, Philip J. "Investigation of finger motion in two quadrupedal dinosaurs: the sauropod Camarasaurus and stegosaur Stegosaurus." Alcheringa: An Australasian Journal of Palaeontology (2026): 1-11. White, Matt Andrew, et al. "Beneath the waves: Extraordinary dietary insights from a dismembered ichthyosaur from the lower Cretaceous." Gondwana Research (2026).

The gang discusses two papers that technically involve symbiosis. The first paper looks at fossil evidence for tape worms, and the second paper is a review of the various evolutionary hypotheses of the convergent origin of viviparity (live birth). Meanwhile, Curt imagines a new theme park, James has a good night, and Amanda surprises us all.   Up-Goer Five (Curt Edition): The friends look at two papers that look at things that live inside of other animals. The first paper looks at an animal that lives inside other animals and eats their food from the inside. This paper finds very old shit and in some of this shit they find the things that these animals that live inside of you use to make more of themselves. The second paper goes over the ways that animals can grow smaller animals of themselves inside of themselves, and all of the reasons why that might happen.   References: Dentzien-Dias, Paula, et al. "Multiple records of tapeworm eggs from Permian coprolites and their palaeoparasitological significance." Acta Palaeontologica Polonica 71.2 (2026): 323-335. Whittington, Camilla M., Mitchell J. Hodgson, and Christopher R. Friesen. "Convergent evolution of pregnancy in vertebrates." Annual Review of Animal Biosciences 13.1 (2025): 189-209.

The gang discusses two papers that use fossils to understand ecological interactions in the past. The first paper reports predation patterns on fossil blastoids, and the second paper finds brooding in the soft tissue of fossil bivalves. And then… the gang gets very much back on their bullshit… Meanwhile, James simplifies his life, Curt discusses new business ventures, and Amanda is seen.   Up-Goer Five (Curt Edition): The friends look at two papers that look at how animals from a long time ago lived their lives. The first paper looks at a group of animals made of small hard parts with a big round head and tiny things coming off the head that it uses to eat. People did not think that animals ate these animals in the past, but this paper finds a few bits that show they were eaten. It uses a lot of looking at other things to say that this may have been eaten by a fish. The question then is, do we not see more of these animals that have been eaten because the fish don't try to go for them most of the time, or because when they do go for them they completely blow them up when they eat them. The second paper looks at a group of animals that has two hard parts on either side of them. These animals usually fall to pieces when they die because of the soft bits that go away. This paper looks at dead animals that did not fall to pieces because they got covered in the ground before that happened. This paper looks at parts of these that they show are soft bits from a long time ago. They also show the parts where the animal would get water in to breathe, and in that part they find small little animals of the same animal. This is a group that makes little ones that live in these parts that take in water, but start in the parts of the mother. This shows that this was happening in the past in ways that are like how they happen today.   References: Delvene, Graciela, et al. "Exceptionally preserved embryos reveal maternal care in freshwater bivalves since the Cretaceous." Scientific Reports 16.1 (2026): 17691. Drumheller, Stephanie K., Colin D. Sumrall, and J. Richard Kyle. "Crunchy on the outside, chewy on the inside: evidence for vertebrate predation and recovery in the Mississippian blastoid Pentremites spicatus." Lethaia 60.1 (2026): 1-12.

The gang discusses two papers that describe fossils which provide glimpses into the evolution and ecology of animals that were "late editions" to their clade. In other words, this podcast is focusing on fossils whose ages place them were close to the extinction of their respective groups. The first paper identifies ecological preferences in late Paleozoic trilobites, and the second paper describes a terror bird from South America that provides further evidence for a younger extinction of the group than traditionally understood. Meanwhile, Curt proposes a sitcom, Amanda has great timing, and James enjoys watching robots fail.   Up-Goer Five (James Edition): This week the group read two papers about some of the last members of some groups of animals that are now dead. The first paper looks at small animals with hard skin and lots of legs that can roll up into balls. Although these animals used to come in lots of different shapes, by this time they come in only a few different shapes and are thought to all look like each other. The animals in the paper are found toward the end of when they lived and come both rolled up, all stretched out, and broken up into little bits, showing that some of them were moved into where they are found by water. The animals found in the area are of two different kinds that are almost the same to each other but are found in different parts of the area, with one living in water that is not as deep and the other living in deeper water, showing that they were doing different things. The other paper is looking at the bone of a big angry animal that walked and had a body covered in things that are not hair but would have helped it fly if it was not so big. This one is found long after we thought these animals all died, and is also found from the bottom of the two big bits of land that got married at some point. When these bits of land got married, a lot of animals moved to the bottom bit of land and some moved to the top bit. These animals moved to the top bit and then went missing from the bottom bit, but because this animal bone was discovered we know that they actually still were in the bottom bit long after we thought they went missing.   References: Kudo, Nakuru, and Yuta Shiino. "Taphonomy and environmental distribution of Pseudophillipsia in the middle Permian Kamiyasse Formation of the Southern Kitakami Terrane, Japan." Journal of Paleontology (2026): 1-18. Machado, Victor Hugo M., et al. "A new terror bird (Cariamiformes, Phorusrhacidae) from the Late Pleistocene of Brazil: insights into the last representatives of the family." Papers in Palaeontology 12.2 (2026): e70080.

The gang discusses two papers that look at early tetrapods. The first paper investigates the transition to terrestrial environments in early tetrapods, and the second paper looks at some very small Dimetrodon. Meanwhile, Amanda has a disproportionate cat, James talks smack about a dead synapsid, and Curt gives gardening tips.   Up-Goer Five (Amanda Edition): This week our friends look at two papers on animals with hard bits in their back and four legs. The first paper asks when did animals with hard bits in their backs and four legs first start doing a big change as they grew up. Today the sort of early group of animals with hard bits in their back and four legs are really not that early and are actually really different but a lot of people use them to talk about early animals with hard bits in their backs and four legs. They do a big change as they grow up. They start out using water to breathe and then change to breathing air. Some of them grow legs when they don't start with legs. People like to say that this means early animals with hard bits in their back and four legs also must have done a big change as they grew. But actually maybe not, because old animals with hard bits in their back and four legs don't show the big change at all. So it seems like maybe the big change either came about once before a big branch between groups, and then went away in animals with hard bits in their back that live on land, or it came about twice in two different groups of animals that do a big change as they grow, one of which might have become the living group of animals with hard bits in their back and four legs that do a big change and live in both water and on land. Both of those might have been the right answer but we can't tell right now, we need more old animals to find out. The second paper is about a animal with hard bits in its back and four legs that is close to animals with hair, but probably did not have hair. Instead it has a big back with things sticking out and skin on it. These ate other animals and were really important when they lived. But the paper looks at animals in this group that are small. It's very different too because many of these animals are found in one part of the world, but one of the small ones is found far away. It's the only one not found with all the others. The other small one is found with all the others. This paper wants to find out why are they small and do they get small in the same way, so they cut up the inside hard parts and look at them really close and find that they actually get small in different ways because they can see how they grow when they look at the inside hard parts up close. They also think that the animals that lived in the far away place from the others were small for a different reason, because the place they lived was not great and they maybe didn't have a lot of food to eat. The small ones that are found with all the other animals were small because there were all those other animals with big backs with things sticking out and skin on it that would fight it. So they probably lived more in water and ate fish, maybe.   References: Pardo, Jason D., and Arjan Mann. "Direct development of stem tetrapods across the fin-to-limb transition." Science 392.6804 (2026): 1292-1296. Canoville, Aurore, et al. "Contrasting life history in the diminutive Dimetrodon species from North America and Germany." Scientific Reports 16.1 (2026): 16279.

The gang discusses two papers about jawless fishes. The first paper looks at some soft tissue preservation of early vertebrates which include preserving evidence of an ancient heart, while the second paper investigates how the fossil record of hagfish can inform the order in which characteristics evolved within the group. Meanwhile, James "solves" his problems with machines, Amanda keeps making new friends whether they like it or not, Curt claims no responsibility, and everyone loves these kawaii line drawings.   Up-Goer Five (James Edition): This week the group look at two papers that are about different animals that have no legs and live in water. The first paper is about a very strange animal that lived a very long time ago that people have thought might be an early part of the group that is made up of things with hard parts inside. The paper looks at things inside the animal and show that they are made of old blood showing the parts of the animal that carried the blood and the parts that clean it. These parts suggest that the animal is in fact an early part of the group that eventually get hard parts inside. The second paper looks at three animals that are part of the group of animals that make thick wet stuff and have a mouth that does not move. They also have small eyes under the skin and live in deep places and it has been thought they show what all animals with hard parts inside used to be like. These three old animals show how the eyes have changed over time and that these animals used to have normal eyes. One of the animals is starting to get small eyes and this shows that the eyes did not get small because they lived in the dark because this one is from water that is not deep.   References: Tian, Qingyi, et al. "Evidence for aorta and other blood vessels in fossil yunnanozoans from the Cambrian period." Royal Society Open Science 13.6 (2026): 260043. McCoy, Victoria E., et al. "Stepwise loss of complexity in hagfish eyes prior to deep sea colonization." Biology Letters 22.5 (2026): 20260127.

The gang discusses two papers that use fossil material to assess the origin of animal groups. The first paper describes a new Early Devonian fish and its implications for the evolution of jaws, and the second paper reassesses the fossil material of turtles (and possible not turtles) to determine where turtles fit on the evolutionary tree of sauropsids. Meanwhile, James invents new flavors, Curt breaks things down, and Amanda sets boundaries.   Up-Goer Five (Amanda Edition): Today our friends look at two papers that talk about things showing up for the first time. The first thing to show up for the first time are teeth. Animals with inside hard backs have teeth, but how those teeth first show up are a big question mark. Turns out that teeth first show up as not-teeth and can actually grow over each other and grow in weird ways that today's teeth can't grow in. It also turns out that these early animals with hard backs and mouths that open and close had these sort of teeth and they're pretty much from the same stuff as the teeth we have today, so these are the same thing over time. The second paper our friends look at has to do with animals with inside hard backs that also have outside hard backs. We didn't know for a long time where these animals came from. Now we know, and they look at a really old weird animal that we thought might be one of those animals with inside hard backs that also have outside hard backs. But it isn't, it is too old and has inside parts of its head that don't look right. So now we know that animals with inside hard backs that also have outside hard backs are actually closer to animals with cold blood and big long faces that sit in water all the time and attack animals that come to drink water.   References: Olive, Sébastien, et al. "A new 'acanthothoracid'placoderm from the Arctic Canada (Early Devonian) and its bearing on the evolution of jaws and teeth." Royal Society open science 12.9 (2025). Jenkins, Xavier A., et al. "The phylogenetic origin of turtles." Current Biology (2026).