The Common Descent Podcast

Earth’s oceans change over time, not just in their size and shape, but also in the very dynamics of their ecosystems. The stage was set for modern ocean ecosystems by an event called the Mesozoic Marine Revolution, a dramatic restructuring of ecology in shallow seas that saw the rise of many forms of active predatory lifestyles. This episode, we discuss the fossil evidence, the major players, and...

Eating plants isn’t easy, and yet the habit has evolved many times over the history of life on Earth, and herbivores have become essential components of ecosystems as we know them. This episode, we discuss the adaptations animals use to get around the challenges of plant-eating, as well as the incredible history of the repeated origins of herbivory. In the news: vampire squids, death by ammonite,...

There’s a new paleontology-adjacent movie out there, and as usual, it’s a great opportunity to examine how science is translated to the big screen. Back to the Cretaceous (kind of) – 65 (2023) Check out our website for more stuff: http://commondescentpodcast.com/ Join us on Patreon to support the podcast and enjoy bonus content! https://www.patreon.com/commondescentpodcast Got a topic you want to...

For much of their evolutionary history, whales have been divided into two main lineages: baleen whales and toothed whales. The toothed variety are especially diverse today, including sperm whales, belugas, porpoises, and so, so many dolphins (among others). This episode, we explore what makes toothed whales distinct – besides the obvious – and what the whale fossil record tells us about how they c...

Throughout Earth history, tectonic forces have changed the shape of the continents – and the oceans! You might be familiar with the Tethys Sea as an ancient ocean nestled against Pangaea, home to marine reptiles and more, but there’s actually a whole series of ancient bodies of water that bear this name. In this episode, we explore the various iterations of the Tethys, discuss how geologists study...

Mammals are famous for their ability to produce milk, a special substance that is essential for providing newborns with the ingredients they need for healthy development. As it turns out, mammals aren’t the only ones. Milk-like substances have evolved in many groups of animals which nourish their developing young. In this episode, we discuss what milk is, what it does, how it seems to have evolved...

Happy Snake Month! In this special episode, it’s all about snakes with our very own snake-enthusiast: David! Thanks to our Patrons for providing the inspiration for these interview questions! Join us on Patreon to support the podcast our scaly friends! https://www.patreon.com/commondescentpodcast Check out our blog for bonus info and pictures: http://commondescentpodcast.com/ We’re an Audible Affi...

Snakes are surprisingly good at adapting to life in saltwater. Today’s seafaring serpents include a wide diversity of semi-marine species as well as a fascinating assortment of fully oceanic snakes, and this is a tradition that extends well into the past, with numerous radiations of ancient sea snakes. This episode, we explore the repeated evolution of marine lifestyles in snakes, and the array of...

Most crocodilians today can handle saltwater to some degree, but many of their ancient cousins were much more suited to a life at sea, including some of the most impressive ocean-going reptiles in history. In this episode, we’ll explore the many lineages of marine crocs that have evolved over the last 150 million years, and we’ll dive into the special adaptations that allowed them to take to the s...

Happy Croc Month! In this special episode, we talk about crocs with the croc-fanatic himself: our very own Will! Thanks to our Patrons for providing the inspiration for these interview questions! Join us on Patreon to support the podcast our scaly friends! https://www.patreon.com/commondescentpodcast Check out our blog for bonus info and pictures: http://commondescentpodcast.com/ We’re an Audible...

When scientists find a new rock formation or fossil assemblage, how do they determine how old it is? The answer lies in the many varied methods of geologic dating. In this episode, we’ll discuss how we can sort the events in Earth history, how we calculate specific ages for ancient materials – including a deep-dive into radiometric dating! – and most importantly, how these many techniques support...

In our modern world, there are three major groups of mammals: placentals (that’s most of us), marsupials, and the rare and bizarre monotremes. Today’s monotremes – that’s echidnas and platypuses – are famous for their seemingly “un-mammalian” features: they lack external ears, they deliver milk without nipples, and they even lay eggs! This episode, we discuss what makes monotremes unique, the many...

One of the hallmarks of angiosperms (flowering plants) is the formation of a container to hold their seeds. These containers are fruits, and they come in an astonishing variety of forms and functions, far beyond the typical line up of fruits, nuts, and berries we see at the grocery store. Join us and our favorite paleobotanist Dr. Aly Baumgartner as we explore what fruits are, what fruits do, and...

From roughly 1.8 – 0.8 billion years ago, things on Earth seemingly slowed down. The geologic record shows a conspicuous lack of evidence for major climatic, tectonic, or biological changes, a dramatic contrast to the tumultuous times before and after. In this episode, we explore this so-called “Boring Billion” and discuss what made it so unusual. Along the way, we’ll examine claims that there mig...

As you might know by now, our high-level supporters on Patreon get to request a topic for their own special mini-episode! Every now and then, we collect the most recent of these and put them together into a compilation for everyone to hear. This is our third one! A huge thanks as always to our Patrons for their kind contributions to our education efforts. 00:00:00 Intro 00:02:15 Stegosaurs for Sea...

Check the fingers and toes of your favorite vertebrate animals and you’re likely to find claws or something similar at the ends. These digit-caps come in a variety of shapes – claws, nails, even hooves – for a variety of functions. In this episode, we discuss the close relationship between claw form and function, how we study claws in the fossil record, and the intriguing questions of how claws ca...

You’re probably familiar with frogs and salamanders, but there is a third group of modern amphibians, the strangest of them all: the worm-like caecilians. In this episode, we’ll explore the many bizarre anatomical features of caecilians, from their tentacled faces to their abrupt hind ends. Then we’ll explore the entire caecilian fossil record (it won’t take long) and tackle the much-discussed mys...

We spend a huge portion of our lives sleeping. For us and other animals, it’s clearly a very important behavior. And yet, despite how familiar and commonplace it is, there’s plenty we still don’t understand about sleep: its origins, evolution, and even how to define it in the first place. In this episode, we explore some of the remarkable variation in animal sleeping habits, we discuss some of the...

Once, it was a volcanic crater. Then, it was a lake, perhaps equal parts lush and deadly. Much later, it was a mining site. And finally, today, it is a UNESCO World Heritage Site and one of the most famous and heavily studied fossil sites in the world. In this episode, we discuss the history and formation of the Messel Pit, and we ooh and aah over a small sampling of the many thousands of incredib...

Giraffes are so famous and familiar to most of us that it can be easy to forget how utterly strange they are. This episode, we explore modern giraffes, their living cousins (okapis!), and their ancient relatives to understand how these monumental mammals came to be how they are. Along the way, we’ll meet a whole variety of wacky-horned fossil species, and we’ll tackle the questions of how and why...

Happy Darwin Day! You’ve seen his artwork. And if you somehow haven’t, you’ve seen lots of art inspired by his artwork. Charles R. Knight might be the most influential paleoartist of all time, inspiring a century’s worth of artists, scientists, and ancient-animal-enthusiasts around the world with his skillful and scientifically-informed works. In this episode, we explore who Knight was, how he bec...

Glowing organisms might seem like something out of science fiction, but not only do they exist here on Earth, they are incredibly common. Some species glow when exposed to certain kinds of light, and others produce their very own light in the darkest habitats on the planet. This episode, we explore glowing life: how they do it, what they use it for, and what we can tell about how this remarkable a...

The Paleozoic Era was home to many strange and fascinating extinct groups, and among the most eye-catching of these were the eurypterids. Colloquially called “sea scorpions,” these carnivorous aquatic arthropods came in many forms for many habitats and are now known from many amazing fossils. In this episode, we discuss what makes eurypterids distinct from similar organisms, what we know about the...

Happy New Year! It’s been an exciting and eventful year for the podcast, and we’re glad you’ve been along for the ride! As usual, this is our annual Q&A where we answer the many, many questions our listeners submitted – the scientific, the silly, and the personal. Thanks as always to all of our listeners, our Patrons, our special guests, and to everyone who supports the podcast in ways big and sma...

It’s a great time of year to talk about conifers! Also their cousins: cycads, ginkgos, and others! Gymnosperms don’t get nearly as much love and attention as their flowering counterparts, the inescapable angiosperms, but they nonetheless have their own fascinating history going all the way back to some of the earliest forests on Earth. This episode, we’re joined once again by our favorite paleobot...