Let’s just get into it - dinosaurs pooped and sometimes that poop fossilized and these two facts have brought an incredible amount of joy to my life. That’s right, we’re talking coprolites! Of course, other animals pooped too and their poop also fossilized. Coprolites are any fossilized feces from any animal, and I am a big fan of all of them.
a coprolite from South Carolina, between 5 and 23 million years old
Coprolites are trace fossils, meaning they are not fossils of the animal itself but rather a record of a behaviour performed by that animal, like a footprint or a burrow. Or a turd. Body fossils are pretty amazing by themselves, but trace fossils are great because they teach us about the behaviors of extinct animals. How they lived, how they traveled, or what their social lives were like are all things we can learn about from trace fossils.
a coprolite cut lengthwise and polished to showcase the unique interior patterns
The most obvious thing coprolites show us is of course the animal’s diet. Bone shards, scales and bits of insects are all found in fossil feces, but we can also find plant matter, and even bacteria. From that, we can start to put together a picture of an ecosystem from millions of years ago! Pretty incredible!
a coprolite with the toe bone of a deer inside
And it’s not only what is inside the poop that is of interest, what happened to it after it was left behind can also be informative. Teeth marks from scavengers and burrows created by ancient insects fill in our understanding of what the world was like eons ago.
Just think about that for a second - an animal pooped millions of years ago and that poop landed in a place where the conditions were right for fossilization. It wasn’t melted or crushed by plate tectonics, it didn’t get weathered away by the elements, it survived until someone came along and found a rock that looked like poop and decided to study it. Or make jewelry out of it ;)
a nicely cut coprolite showing the rough exterior and a smoothly polished interior
Now let’s address the questions I always get when talking to folks about fossil poop. 1) How do you know it’s poop and 2) who pooped it?
The first question is much easier to answer: the shape, the contents, and the location where a coprolite was found are all clues used to identify it. Here’s a fun fact - some coprolites are found in the abdominal region of body fossils, they are pre-poops! Question #2 (ha!!) is more challenging. We can figure out the size of the animal and whether it was an omnivore or carnivore fairly easily, but assigning it to a specific genus is very difficult and often not possible. There are a few instances where it is possible though. First, if the poop has not yet been excreted like I mentioned above, that makes it pretty easy. If the coprolite is found in a bone bed of numerous individuals of the same species, and the size and contents match with what we know that that species ate, we can pretty confidently assign it to that animal. If we are REALLY lucky, using location, contents and process of elimination can yield a positive ID like with this confirmed T Rex turd found in Canada. Due to the large size of the specimen and the prey animal remains found inside, scientists were able to conclude that Tyrannosaurus Rex was the only dinosaur in that region that could have produced it!
not-shiny coprolites and shiny coprolites from my collection
Here’s another question (or two) that I get a lot about coprolites - how did it end up so pretty and why do some look like actual turds and some look like gemstones? I get this about the fossil dinosaur bone I use in my jewelry as well and the answer is the same. It all depends on the conditions during fossilization. Once the original bone or poop has been buried, minerals will seep in from the surrounding groundwater and replace the organic matter with stone. If silica or other ‘pretty’ minerals are present in the groundwater and replace the organic material, you end up with nice colors and a fossil that is hard enough to take a nice polish. This is sometimes called an agatized fossil. If the not-so-pretty minerals do the replacing, you end up with the kind of dull, earth tone fossils that you typically associate with dinosaur bones. All fossils are beautiful and interesting, but humans just tend to prefer adorning themselves with shiny colorful things ;)
I hope I piqued your interest in this fascinating and amusing material, there is so much more to it than what I covered in this post. Here are some recommendations if you are craving more coprolite content:
- The Karen Chin episode of the PaleoNerds Podcast - I am a fan of this podcast in general, and Karen Chin is the expert on fossil feces
- The Poozeum and their book, Coprolites of the World are both a treat
- If you need some shiny poop of your own to wear you can check out my online shop or email me to see what's available - firstname.lastname@example.org
As always, thanks so much for reading. You are appreciated!
*I apologize for all the poop jokes, but you should know that I really held back...it could have been worse! And in case you were curious...my #1 favorite fossils are trilobites. But you probably knew that :)
*** I am not a scientist or an expert on any of the topics I cover on this blog, I am just an enthusiastic rock and fossil fan trying to spread the love. I encourage you to do your own reading and research on any topics that might strike your fancy. If you are an expert and would like to gently correct me, please do! You can reach me via email at email@example.com. You can also reach out to tell me how I totally nailed it, or just to say hi, or to show me some cool rock you found.***