Episode 238 - Osteoderms (Skin Bones)

The Common Descent Podcast

Common Descent

Science, Natural Sciences, Education, Earth Sciences, Science:natural Sciences

4.8 • 764 Ratings

🗓️ 1 March 2026

⏱️ 156 minutes

🔗️ Recording | iTunes | RSS

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Summary

Some bones are only skin deep! In many species of reptiles, mammals, and amphibians, bones called osteoderms develop within the skin, serving as body armor, additional muscular support, display features, or any number of other functions. This episode, we explore the extraordinary diversity of osteoderm anatomy, we take a tour through the many and varied osteoderms of Earth history, and we investigate a long list of hypothesized functions for these unusual bones. In the news: reptile skin, dinosaur quills, dinosaur bites, and cannibal snakes. Time markers:Intro & Announcements: 00:00:00News: 00:06:25Main discussion, Part 1: 00:46:35Main discussion, Part 2: 01:26:35 Patron question: 02:24:05 Check out our website for this episode’s blog post and more: 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 hear about? Submit your episode request here: https://commondescentpodcast.com/request-a-topic/ Lots more ways to connect with us: https://linktr.ee/common_descent The Intro and Outro music is “On the Origin of Species” by Protodome. More music like this at http://ocremix.org Musical Interludes are "Professor Umlaut" by Kevin MacLeod (incompetech.com). Licensed under Creative Commons: By Attribution 3.0 http://creativecommons.org/licenses/by/3.0

Transcript

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0:00.0	You're listening to the Common Descent Podcast.
0:19.0	Hello, Will. Hello, David. Hello, listeners, and welcome to episode 238 of Common Descent. This episode, our topic is osteoderms, aka skin bones. Yes, good stuff. This is a really fun one.
0:42.8	Osteoderms are a topic that has come up a lot on the podcast, and this is a part of animal anatomy that you and I are both extremely familiar with.
0:48.2	Yes.
0:48.5	Because we've both worked on animals that have osteoderms, But it is a fairly obscure piece of anatomy.
0:56.8	Yeah, but it's one of those that needs to be defined every time it's said.
1:00.6	Yes, this is something where I wouldn't be surprised if a bunch of our listeners are only familiar with this concept, because they've heard us talk about it.
1:08.5	Yep.
1:09.5	So in this episode, we will talk about what osteoderms are,
1:13.8	what we're discussing, what the morphology,
1:16.8	the anatomy of these bones is,
1:19.1	how they form in the skin,
1:21.4	and who has them, right?
1:23.6	This is the bony armor of things like alligators
1:26.6	and a bunch of lizards and armored dinosaurs.
1:29.4	And we'll go through the long list of not only modern but ancient organisms that have osteoderms and the even longer list of potential functions of what these osteoderms are actually doing to the benefit of these animals.
1:46.8	Yeah, surprisingly versatile for just being bits of bone in the skin.
1:52.1	This was a really fun episode to prepare for because I knew that it was going to be mostly
1:57.6	just you and me geeking out about our favorite examples of this thing. Yeah. So please enjoy that. It's going to be a whole lot of fun. This is, my hope is that this becomes one of those episodes that people comment and say, man, when I saw the title, I wasn't sure I was going to enjoy it, but then I really learned a lot and liked this discussion. So if it's one of those, let us know.
2:18.2	And if it's not, don't let us know that. Yeah, we're good. This episode topic also was requested,
2:24.0	as all of our topics are by our listeners. This one comes to us thanks to Lydia, Fen, Apollo,
2:31.6	and Jonathan. Great request. Before we get into the meat, or in this case the bones within the meat, and Jonathan. Great request.
	...

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