Learning is a joy in life, and learning about birds is one of the universal truths of birding. What we learn can vary tremendously – we may learn what seeds our backyard birds prefer, how to identify a new bird we see, or where our favorite birds are migrating. I’ll confess, however, I never intended to learn about fossilized bird poop.
Okay, I never thought fossilized poop – from any species – was a thing to learn about.
But it started with a fun word – coprolite. Sounds spritely and intriguing, doesn’t it? But what does it mean?
Fossilized poop. Or feces, or dung, or excrement, or any other word you want to use for the leftover waste that isn’t digested. But it turns out that coprolites are far more fascinating than just a fun word, they really can provide startling insights into the daily lives, diets, and habits of prehistoric creatures, including birds.
Let’s start with the basics – coprolites are very rare, much rarer than many other types of fossils. Because waste material breaks down quickly when exposed to rain and sun, and because smaller scavengers may root through poop to consume what bits they can, there usually isn’t much poop left to become fossilized, particularly as fossilization takes many years, from decades to centuries depending on the conditions of the sample as well as the climate and geography. When poop is left in the right place, however, such as on sediment that quickly becomes buried, perhaps a soft surface or near an avalanche or landslide site, the conditions are better for its fossilization and the poop may be preserved.
The fossilization process for poop is the same as for other organic material. The original organic compounds are slowly replaced by inorganic minerals. In the case of coprolites, that replacement is typically with silicates and calcium carbonates. Because a coprolite no longer contains its initial organic material, it does not smell and no longer decays. In fact, some coprolites become quite beautiful with red, orange, yellow, pink, green and other colors in their mineral structure, with patterns and designs similar to agate. You can even buy coprolite jewelry, beads, and other ornaments (there’s a fun gift – fossilized poop!).
Paleontologists study coprolites to learn about the diet of the animals that excreted the feces, such as whether an animal was herbivorous or carnivorous, whether it ate humans or what other prey it may have favored. Trace elements and remnants such as small bones, seeds, teeth, plant material, or scales still present in the fossilized feces offer those clues, and the size, shape, and structure of the coprolites can reveal even more about the digestive tract of the animal. Fossilized bacteria within the samples can also indicate diseases or gut composition. This type of study is very similar to how ornithologists will dissect and examine the pellets regurgitated by many raptors, kingfishers, and other birds.
So what do fossilized coprolites have to do with birds today? Modern birds, of course, excrete both urine and feces at the same time and through the same opening, rarely making samples that would be successfully fossilized. To do that, you’d need a very large bird, and it just so happens the extinct moas of New Zealand left behind perfect poops to become coprolites. Paleontologists have studied these fossilized remains, and determined the diets of these amazing, 12-foot-tall, 500-pound birds. Moas ate a great deal of mushrooms and fungi, while some of them also preferred ferns, mosses, or snails. This also helps reveal more about local ecosystems, and how the birds likely contributed to spreading plant seeds and spores around through their droppings, just as many modern birds do today. The more we learn about ancient birds, the better we understand our modern feathered friends and the roles they play in our ever-changing world.
And that’s the straight poop.
Want to learn more about coprolites?
Visit the Poozeum! (Seriously, I can’t make this shit up…)