SOLOMONS, MD – January 13, 2022 – Given the right environmental conditions, feces can fossilize. When they do, they are referred to as coprolites. In a paper just published in Rivista Italiana di Paleontologia e Stratigrafia (= Research in Paleontology and Stratigraphy, an Italian – yet international – paleontological journal), paleontologists from the Calvert Marine Museum (Solomons, Maryland) and the University of Pisa (Italy) collaborated to describe two different kinds of coprolites: 1) tiny fecal pellets (micro-coprolites) probably produced by scavenging worms and 2) extinct crocodile coprolites that were tunneled into by poop-eating animals.
The most amazing fossil that preserves the fossilized worm feces is a stargazer fish partial skull that is completely infilled with fecal pellets (Figs. 1 and 2). It is the first skull known in the fossil record to be infilled with feces. After the fish died, scavenging worms on the ocean floor ate their way into the fish’s skull, while filling the emptied spaces with tiny poop pellets (i.e., the micro-coprolites).
The scientific name given to these micro-coprolites is Coprulus oblongus (which translates to “oblong fecal pellets”). The fecal pellets are found in small clusters or strings of dozens, to masses of many hundreds (Figs. 1 – 3). Pellets are approximately 1/8 of an inch long and vary in color from gray to brownish-black. These tiny coprolites have been found in a variety of fossils including a fish skull (Figs. 1 and 2), snail shells, clamshells (Fig. 3), barnacles, and in burrows. Because the fossilized fecal pellets are often found in tiny spaces or spaces thought to be inaccessible to shelled invertebrates, they are attributed to small, soft-bodied worms.
Some much larger coprolites attributed to crocodiles (Fig. 4) found along Calvert Cliffs were tunneled into, presumably the result of animals engaging in coprophagy (the term referring to the eating of feces), yum! The researchers do not know what kind, or kinds, of animals, ate their way into the originally edible crocodile droppings. The fate of the vast majority of the Miocene epoch fecal masses was likely that they were completely eaten. The animals engaged in coprophagy were recycling nutrients present in the feces. If there hadn’t been recycling of feces, the ocean floor would have been buried deep in droppings.
These 8-18-million-year-old coprolites (both the micro-coprolites and those produced by crocodiles) were found by amateur and professional paleontologists along Calvert Cliffs and the surrounding area. These coprolites were preserved in sediments that were laid down over millions of years on the bottom of the Atlantic Ocean when it covered southern Maryland.