Trilobite Paleophysiology
Even though the abstract includes the word “iconic”, I recommend an article from Nature, Uniquely preserved gut contents illuminate trilobite palaeophysiology,
The official citation is:
Kraft, P., Vaškaninová, V., Mergl, M. et al. Uniquely preserved gut contents illuminate trilobite palaeophysiology. Nature 622, 545–551 (2023). https://doi.org/10.1038/s41586-023-06567-7
It appears to be open access, you can download a PDF
I think I’m conscious of trilobites after reading Richard Fortey’s Trilobite book, but this paper illustrates interesting things about paleontology.
The paper is about a specimen of a trilobite species first described in 1872, Bohemolichas incola (Barrande, 1872). Europeans have been aware of and studying fossils of this species for about 150 years. Previous to this paper “no trilobite specimen with internal gut contents has been described”. Paleontologists gnaw on problems for centuries.
Paleontologists do detective work, solving puzzles with not many clues. They figure out where this poor individual’s gut was, and note that it’s filled with stuff like arthropods shells, echinoderm shells, and brachiopod shells, but they’re not digested. This allows the authors to deduce that this trilobite had an alkaline or at most a neutral pH digestive system, which is conveniently also the case in arthropods today. This trilobite lived in the Middle Ordovician was 463 million years ago. It is simply astonishing this can be reasonably determined.
Paleontologists cross reference everything “Inferred diets” or modes of life can occasionally be hypothesized via mouth size and shape, and for vertebrates, teeth size and shape. No trilobites had teeth as such, but least some trilobites, including this one, have a “hypostome”, a calcified body part used in feeding. There’s evidence of Ordovician scavengers burrowing through the mud just after the trilobite died, then scavenging soft tissue, but not the gut. The authors deduce that digestive enzymes or gut pH offended the scavengers.
The authors hypothesize a life style for this trilobite as a “light crusher” and chance feeder on shelled animals, other arthropods or mollusks that were small enough, or had thin enough shells to crush with its hypostome, or consume whole. There are animals alive today that eat by crushing shelled animals, mollusks and similar, that are technically carnivores, but the specialized word is “durophagous”. According to the authors, this trilobite isn’t truly durophagous. because it consumed shelled animals based on size, or ease of breaking up their shells. The trilobite didn’t pick out specific kinds of shelled animals, which is more typical for durophagous animals.
An interesting, well-written paper.