Podcast 296 - An Arm and a Head

The gang discusses two papers that detail interesting findings about the soft tissues of extinct arthropods. The first paper does a detailed study of the limbs attached to the trilobite head. The second paper describes the newly discovered head of the ancient myriapod Arthropluera, and discusses the larger implications this fossil has for the evolution of millipedes. Meanwhile, Curt explores new advertising ventures, Amanda unpacks automotive anxiety, and James has no ethical complications to report concerning this podcast.   Up-Goer Five (Curt Edition): The friends look at two papers that look at parts of dead animals that have lots of parts that repeat over and over again and take off their skin every time they get bigger. The first paper looks at a group of these dead animals that are no longer around but are found a lot in the past. This paper shows that the number of legs in the head is different than we thought it was. They show that there are five legs in the head, and that it was hard to see in a lot of these animals because of the ways that we get these animals in the rocks makes it harder to see. The second paper looks at an animal that we think is a lot like animals we see today with long bodies and two legs on each part. But we never actually found the head of these animals. This paper finds the head and it helps to show us a lot of cool things about not just these animals in the past, but also how these animals have changed over time. This helps us understand why the groups we have today are the way that they are.   References: Lhéritier, Mickaël, et al. "Head anatomy and phylogenomics show the Carboniferous giant Arthropleura belonged to a millipede-centipede group." Science Advances 10.41 (2024): eadp6362. Hou, Jin‐bo, and Melanie J. Hopkins. "New evidence for five cephalic appendages in trilobites and implications for segmentation of the trilobite head." Palaeontology 67.5 (2024): e12723.

The gang discusses two papers that look at examples of soft tissue preservation during the Cambrian. The first paper is a deep dive into the sedimentology and paleoenvironment of the Emu Bay Shale. The second paper makes some interesting claims about soft tissue preservation in a marginal marine environment. Meanwhile, James needs some shortcuts, Curt is locked up, and Amanda should be blamed for everything that happened here.   Up-Goer Five (Curt Edition): The friends look at two papers that look at animals from a long long time ago that lived in the water and were soft but were able to be found in rocks. The first paper looks at a place where there are a lot of animals found in rocks but the types of animals are different from other places around the same time. This paper looks at what the place was like at that time and they see that this was a place where a long line of water that you can drink made its way into the big water that you can not drink. The second paper made us all sad.   References: Naimark, E. B., A. V. Sizov, and V. B. Khubanov. "Kimiltei Is a New Late Cambrian Lagerstätte with the Faunistic Complex of Arthropods (Euthycarcinoidae, Synziphosurina, and Chasmataspidida) in the Irkutsk Region." Doklady Earth Sciences. Vol. 512. No. 1. Moscow: Pleiades Publishing, 2023. Gaines, Robert R., et al. "The Emu Bay Shale: A unique early Cambrian Lagerstätte from a tectonically active basin." Science advances 10.30 (2024): eadp2650.

The gang discusses two papers that look at two Lagerstätten (fossil localities of exceptional preservation). The first Lagerstätte is a unique complex early Triassic community found near the equator, and the second Lagerstätte is a collection of exceptional trace fossils from the Pennsylvanian. Meanwhile, James is convinced in the existence of a town that doesn’t exist, Amanda takes an unexpected break, and Curt once again needs to be redacted.   Up-Goer Fiver: (Curt Edition) The friends talk about two papers that look at times when there was a lot of things in the rocks that we do not get in the rocks during most times, and these times can let us know that there were a lot more things were living at this time. The first paper talks about rocks during a time when usually there is not a lot going on because it was just after a time that most things died. Most rocks at this time do not show a lot of things living. These rocks are cool because they are just after the time almost everything died and they show the things that we know lived through that, and that they are all together in a way that looks like the groups of animals we see in rocks way later. The second paper looks at changes in rocks that are because animals move through or on the ground and that gets in the rocks. This area has a lot of these rocks with the bits of animals moving which lets us know a lot about what things were doing on land a long time ago.   References: Dai, Xu, et al. "A Mesozoic fossil lagerstätte from 250.8 million years ago shows a modern-type marine ecosystem." Science 379.6632 (2023): 567-572. Knecht, Richard J., et al. "Early Pennsylvanian Lagerstätte reveals a diverse ecosystem on a subhumid, alluvial fan." Nature Communications 15.1 (2024): 7876.

The gang looks at two papers that compare similar structures in unrelated animals to see if there might be evidence of convergence. The first paper compares Spinosaurus to phytosaurs and the second paper compares the hyoid bone of ichthyosaurs and toothed whales. Meanwhile, Curt will try it, James waits for something that never happens, and Amanda has a surprise.   Up-Goer Five (Curt Edition): The friends talk about two papers that look to see if animals that are not close are the same in ways because of what they do. The first paper looks at too old and dead big angry animals. Both of these animals look like angry animals today that move in water, and so this paper is looking to see if maybe they were both doing the same thing as what we see today. The paper doesn't come to a strong end, but it looks like maybe these things are doing things that maybe are not always the same as the things that live today that they look like. The second paper looks at two animals that need air but move in the water all the time, one group that is living today and one that has been dead for a very very long time. There is a hard part in them that in the groups that are living today they can use to suck in water to get food to them. People had thought that the old group could have done this too. They looked at this hard part that lets things suck, and they found that the hard part in this old dead group would not let them suck. So these old dead animals would have to get food in a different way than the group living today.   References: Yun, Chan-gyu. "SPINOSAURS AS PHYTOSAUR MIMICS: A CASE OF CONVERGENT EVOLUTION BETWEEN TWO EXTINCT ARCHOSAURIFORM CLADES." Acta Palaeontologica Romaniae 20.1 (2024). Delsett, Lene Liebe, et al. "Is the hyoid a constraint on innovation? A study in convergence driving feeding in fish-shaped marine tetrapods." Paleobiology 49.4 (2023): 684-699.

The gang discusses two papers that look at convergence (maybe?) in modern arthropods. The first paper looks at plant/ant symbiosis in a genus of ants, and the second paper looks at color patterns in crayfish. Meanwhile, James sees through time, Amanda disappears, and Curt plays on everyone’s worst fears.   Up-Goer Five (Curt Edition): The up-goer thing is back and able to be used so we are now happy! The friends look at two papers that look at how animals can look a lot like each other. In this case the animals are really small and made of small hard parts put together. The first paper is looking at some of these small animals that live on trees. These small animals can either live in a lot of trees or just one type of tree. The animals that live on just one type of tree also look a lot like each other. This paper looks at how and why this could be. The second paper looks at the color of small but angry animals that live along big bits of water. These animals can be lots of colors. They find that different colors appear many times in this group. They look to see if there are any reasons why, and what they find is that maybe color is changing because color is not a big deal for the animals that are living under the ground.   References: Probst, Rodolfo S., John T. Longino, and Michael G. Branstetter. "Evolutionary déjà vu? A case of convergent evolution in an ant–plant association." Proceedings of the Royal Society B 291.2026 (2024): 20241214. Graham, Zackary A., and Dylan J. Padilla Perez. "Correlated evolution of conspicuous colouration and burrowing in crayfish." Proceedings of the Royal Society B 291.2026 (2024): 20240632. Thumbnail photo by Vojtěch Zavadil - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=9959681

The gang discusses two papers that...   ok look. I'm going to level with you. No one in this podcast slept more than a few hours before we started recording. One of us was stuck on a plane and didn't get back home until 5 am the day of recording. Everyone was tired and stressed and so we all use this time to vent and drink. Sure, there are papers we talk about: growth rates of Triassic archosaurs and geographic gaps in our early tetrapod record. However, if what you want is focused discussion of the papers, this is not the podcast for you (it takes us 8 and a half minutes to get to the first paper). But if you like us at our most rambling, then do I have a podcast for you!   Up-Goer Five (Curt Edition): Last edition? Oh no the up-goer five word thing has gone down. I can not make an up-goer for this. That makes sense for this because also this time the friends are tired and talking about lots of things that are not the papers, which are about how animals get big and where animals are. But since the nice place that lets us do the word thing is gone, we might not be able to do this ever again. Sorry!   References: Marsicano, Claudia A., et al. "Giant stem tetrapod was apex predator in Gondwanan late Palaeozoic ice age." Nature (2024): 1-6. Klein, Nicole. "Diverse growth rates in Triassic archosaurs—insights from a small terrestrial Middle Triassic pseudosuchian." The Science of Nature 111.4 (2024): 1-5.

The gang discusses two papers that look at modern bird migration patterns. The first paper looks at breading and migration patterns of the American woodcock, and the second paper looks at how migration could function as a motor of island speciation. Meanwhile, James is cursed with consciousness, Amanda is on point, and Curt's jokes are consistently ignored.   Up-Goer Five (Curt Edition): The friends talk about two papers that look at how animals that move in the sky may move a long way to get to a new home every year. The first paper looks at one fun animal that moves up and down along the land where the friends live as everything gets warmer or colder. People have now been following these animals using big things in space that can show where something is, and this is what the paper uses to see how these animals move and how long they stay in one place. They also have people go to these places to make sure the animals are really there and that they are doing the things they think they are doing. This paper finds that these animals also make babies in many of the places that they go. Many animals that move a lot will only have babies once when they get to their new home, but these animals keep making babies in different places as they move. This paper shows that they are doing it and gives some ideas as to why they might be doing this. The second papers looks to see if some of the animals that are stuck on small land with water on all sides. This paper wants to know if a lot of those animals come from animals moving a long way to a new home and getting lost and ending up on this small land. They run a lot of studies to see how many of these animals may have ended up on these small lands this way. And then, they look at other things that these animals have to see if there are big reasons why some animals get stuck. What they find is that a lot of the animals are there because they go stuck. They also find that animals that live in a lot of places and that move with a lot of other animals were the ones that were going to get stuck. This could be because having more of you in more places makes it so you can have at least one group of animals get stuck.   References: Slezak, Colby R., et al. "Unconventional life history in a migratory shorebird: desegregating reproduction and migration." Proceedings of the Royal Society B 291.2021 (2024): 20240021. Dufour, Paul, et al. "The importance of migratory drop-off for island colonization in birds." Proceedings of the Royal Society B 291.2021 (2024): 20232926.

The gang discusses two papers that look at functional morphology in extinct groups. The first paper looks at tooth replacement patterns in an Ornithischian dinosaur, and the second paper studies the shell articulation of Rafinesquina to unravel a long-standing mystery. Meanwhile, James has questions about taste, Amanda forgets protocol, and Curt indulges in his fixations.   Up-Goer Five (Curt Edition): The friends talk about two papers that look at how animals did things a long time ago. The first paper looks at a group of big angry animals that are liked a lot and make their way into movies. This paper looks at how the teeth of some of these animals would grow over time. This group of big angry animals also does a lot of cool things with their teeth over a long time because they move from eating animals to eating things that do not move and make their own food from the sun. The big angry animals that they look at have lot of these animals from a lot of different ages so they can see how the teeth get changed as they grew up. What they see is that the way that the teeth grow in changes as the animal grows older. They also find that the number of times that new teeth come in has changed many times in this group of animals. The second paper looks at a group of animals with two hard parts on either side that sits and eats food from the water. This group of animals has really made people confused for a long time because of how the hard parts come together, which could make it so that the animals could not get water inside to eat and would instead get a lot of ground and die. But this group of animals is really good at what it does because it is found all around the world. So how did these things eat? The paper shows that these animals could move their hard parts a lot more than we ever thought. Also, they show that they could move them pretty quick, and could even push out water so quickly that they could maybe move a little bit if they get covered in the ground.   References: Hu, Jinfeng, et al. "Tooth replacement in the early-diverging neornithischian Jeholosaurus shangyuanensis and implications for dental evolution and herbivorous adaptation in Ornithischia." BMC Ecology and Evolution 24.1 (2024): 46. Dattilo, Benjamin F., et al. "Paradox lost: wide gape in the Ordovician brachiopod Rafinesquina explains how unattached filter‐feeding strophomenoids thrived on muddy substrates." Palaeontology 67.2 (2024): e12697.

The gang discusses two papers that use new fossils to add insight into the geographic origins of groups. The first paper looks at some fossil freshwater dolphins and the second paper looks at fossil jumping spiders. The gang also uses these two papers to talk about a lot of other things because, despite being short papers, there is a lot of related things to talk about. Meanwhile, James is pretty sure he read the papers, Curt has very uninformed opinions, and Amanda gives everyone a panic attack.   Up-Goer Five (Curt Edition): The friends talk about two papers that use old animals to see where animals may have been in the past. The first paper looks at animals with hair that live in the water and have moved into water that you and I can drink. This is a paper about one group of these animals and some bits of an old animal that were found in a place very far away from where these animals are today. This might mean that these animals moved into water than you and I could drink many times over the years and in many places. The second paper looks at a small animal with many legs and hair that eats other small things. These animals are hard to find parts of in the past, but this paper finds a really nice one in a place that is important for understanding how they got where they are today. This group is found in areas that were close to each other in the past but have moved further away. This old animal being found where it is gives us more ideas about how these animals got to where they are today.   References: Benites-Palomino, Aldo, et al. "The largest freshwater odontocete: A South Asian river dolphin relative from the proto-Amazonia." Science advances 10.12 (2024): eadk6320. Richardson, Barry J., Matthew R. McCurry, and Michael Frese. "Description and evolutionary biogeography of the first Miocene jumping spider (Aranaea: Salticidae) from a southern continent." Zoological Journal of the Linnean Society 200.4 (2024): 1013-1025.

The gang convenes in Ann Arbor, Michigan for the 2024 North American Paleontological Convention. We discuss the various talks we saw and highlights on the event. Most of Day 2 discussion starts at 1:03:01 Day 3 discussion starts at 2:19:00 Day 4 discussion starts at 3:22:56