According to a recent article published in the journal Rivista Italiana di Paleontologia e Stratigrafia, a fossilized skull of an extinct species of astronomer fish was filled with tiny fecal pellets known as coprolites. The skull is the first in the fossil record to be completely filled with fecal pellets. This is a joint study by paleontologists from the University of Pisa in Italy and the Calvert Marine Museum in Maryland. Together, the researchers suggested that tiny feeding worms worked their way into the dead fish's skull and expelled the pellets.
Around 1824, British fossil hunter Mary Anning (last played by Kate Winslet in the 2020 film Ammonite) was the first to notice the presence of so-called "bezoar stones" in the abdomen of ichthyosaur skeletons. When he broke open the stones, he often found fossilized remains of bones and scales. A geologist named William Buckland five years later took note of Anning's observations and suggested that the stones were actually fossilized feces. He called them coprolites.
Coprolites are not the same as paleophytes, which contain a large number of organic components that can be reconstituted and analyzed for chemical properties. Coprolites are fossils, so most of the organic components have been replaced by mineral deposits such as silicates and calcium carbonates. It can be difficult to distinguish the smaller coprolites from, for example, eggs or other types of inorganic granules. But coprolites often have spiral or ring markings and, Anning discovered, often contain undigested fragments of food.
For archaeologists interested in learning more about the health and diet of past populations, as well as how specific parasites evolved in the evolutionary history of the microbiome, coprolites and paleophecs can be a veritable gold mine of information. . For example, last year we reported on an analysis of preserved Paleo-Poo that found that Old Iron Age miners in what is now Austria liked beer and blue cheese.
In 2020, we reported on a new method (called CoproID) that can be used to determine whether fecal samples are from humans or from other animals, specifically dogs. (Dog feces bear a surprisingly close resemblance to human feces in size and shape, are commonly found at the same archaeological sites, and have a similar composition.) The method combines analysis of the gut microbiome and host DNA with open-source machine tooling software To learn.
If a coprolite contains fragments of bone, the animal that excreted it was most likely a carnivore, and the tooth marks on those fragments can tell us something about how the animal might have eaten its prey. The size and shape of coprolites can also provide useful information. For example, if a coprolite is spiral-shaped, it could have been excreted by an ancient shark, since some modern fish (like sharks) have spiral-shaped guts.
This new collaborative study examined several fossil samples in the Calvert Marine Museum collection that contained coprolites. The fossils were recovered from Calvert Cliffs in Maryland, with rocks formed from coastal marine sediments that once covered the region. The so-called Calvert Formation is a rich treasure trove for fossil hunters, and although the cliffs are closed to the public, the beach is regularly combed for fossilized shark teeth, which are particularly common.
The most exciting of the fossils the scientists examined was the skull of an extinct species of astronomical fish called Astroscopus countermani, found in 2011 and dating to the Miocene. Astroscopus species surviving today are poisonous and can deliver electric shocks. They hunt by camouflage and ambush their prey, and have been called "the meanest things in creation" by ichthyologist William Leo Smith.
