Trilobites are among the most iconic of fossils and formed a prominent component of marine ecosystems during most of their 270-million-year-long history from the early Cambrian period to the end Permian period1. More than 20,000 species have been described to date, with presumed lifestyles ranging from infaunal burrowing to a planktonic life in the water column2. Inferred trophic roles range from detritivores to predators, but all are based on indirect evidence such as body and gut morphology, modes of preservation and attributed feeding traces; no trilobite specimen with internal gut contents has been described3,4. Here we present the complete and fully itemized gut contents of an Ordovician trilobite, Bohemolichas incola, preserved three-dimensionally in a siliceous nodule and visualized by synchrotron microtomography. The tightly packed, almost continuous gut fill comprises partly fragmented calcareous shells indicating high feeding intensity. The lack of dissolution of the shells implies a neutral or alkaline environment along the entire length of the intestine supporting digestive enzymes comparable to those in modern crustaceans or chelicerates. Scavengers burrowing into the trilobite carcase targeted soft tissues below the glabella but avoided the gut, suggesting noxious conditions and possibly ongoing enzymatic activity.

Centre of Biology Geosciences and Environmental Sciences University of West Bohemia in Plzeň Plzeň Czech Republic

Czech Geological Survey Prague Czech Republic

Department of Organismal Biology Uppsala University Uppsala Sweden

Institute of Geology and Palaeontology Charles University Prague Czech Republic

Zobrazit více v PubMed

Fortey, R. A. & Owens, R. M. in Treatise on Invertebrate Paleontology, Part O, Arthropoda 1, Trilobita, revised. Volume 1: Introduction, Order Agnostida, Order Redlichiida (ed. Kaesler, R. L.) 249–287 (Geological Society of America & Univ. of Kansas, 1997).

Fortey, R. A. The palaeoecology of trilobites. J. Zool.292, 250–259 (2014).10.1111/jzo.12108 DOI

Fatka, O., Budil, P. & David, M. Digestive structures in Ordovician trilobites Colpocoryphe and Flexicalymene from the Barrandian area of Czech Republic. Est. J. Earth Sci.64, 255–266 (2015).10.3176/earth.2015.32 DOI

Hopkins, M. J., Chen, F., Hu, S. & Zhang, Z. The oldest known digestive system consisting of both paired digestive glands and a crop from exceptionally preserved trilobites of the Guanshan Biota (Early Cambrian, China). PLoS ONE12, e0184982 (2017). 10.1371/journal.pone.0184982 PubMed DOI PMC

Havlíček, V. Development of a linear sedimentary depression exemplified by the Prague basin (Ordovician–Middle Devonian; Barrandian area – central Bohemia). Sbor. Geol. Věd, Geol.35, 7–48 (1981).

Havlíček, V. in Palaeozoic of the Barrandian (Cambrian to Devonian) (eds Chlupáč, I., Havlíček, V., Kříž, J., Kukal, Z. & Štorch, P.) 41–79 (Czech Geological Survey, 1998).

Fortey, R. A. Ontogeny, hypostome attachment and trilobite classification. Palaeontology33, 529–576 (1990).

Lajblová, K., Kraft, P. & Meidla, T. Ontogeny of the ostracod Conchoprimitia osekensis (Přibyl, 1979) from the Darriwilian of the Prague Basin (Czech Republic). Est. J. Earth Sci.63, 144–155 (2014).10.3176/earth.2014.13 DOI

Pérez-Peris, F., Laibl, L., Vidal, M. & Daley, A. C. Systematics, morphology, and appendages of an Early Ordovician pilekiine trilobite Anacheirurus from Fezouata Shale and the early diversification of Cheiruridae. Acta Palaeontol. Pol.66, 857–877 (2021).10.4202/app.00902.2021 DOI

Vogt, G. Functional cytology of the hepatopancreas of decapod crustaceans. J. Morphol.280, 1405–1444 (2019). 10.1002/jmor.21040 PubMed DOI

Newman, S. J. & Smith, S. A. Histological characterization of the gastrointestinal tract of the adult horseshoe crab (Limulus polyphemus) with special reference to the stomach. Cell Tissue Res.383, 949–957 (2021). PubMed

Kraft, P., Bruthansová, J. & Mikuláš, R. Feeding traces related to shells from the Prague Basin, Czech Republic (Tremadocian to Early Darriwilian, Ordovician). Paleogeogr. Paleoclimatol. Paleoecol.537, 109399 (2020).10.1016/j.palaeo.2019.109399 DOI

Gutiérrez-Marco, J. C., Pereira, S., García-Bellido, D. C. & Rábano, I. in The Great Ordovician Biodiversification Event: Insights from the Tafilalt Biota, Morocco (eds Hunter, A. W. et al.) 97–137 (The Geological Society, 2019).

Bicknell, R. D. C. et al. Biomechanical analyses of Cambrian euarthropod limbs reveal their effectiveness in mastication and durophagy. Proc. R. Soc. B 288, 20202075 (2021). PubMed PMC

Botton, M. L. Diet and food preferences of the adult horseshoe crab Limulus polyphemus in Delaware Bay, New Jersey, USA. Mar. Biol.81, 199–207 (1984).10.1007/BF00393118 DOI

Bicknell, R. D. C. & Paterson, J. R. Reappraising the early evidence of durophagy and drilling predation in the fossil record: implications for escalation and the Cambrian explosion. Biol. Rev.93, 754–784 (2018). 10.1111/brv.12365 PubMed DOI

Zacaï, A., Vannier, J. & Lerosey-Aubril, R. Reconstructing the diet of a 505-million-year-old arthropod: Sidneyia inexpectans from the Burgess Shale fauna. Arthropod Struct. Dev.45, 200–220 (2016). 10.1016/j.asd.2015.09.003 PubMed DOI

Sherratt, T. N. & Harvey, I. F. Frequency-dependent food selection by arthropods: a review. Biol. J. Linn. Soc.48, 167–186 (1993).

Caldwell, R. L. & Childress, M. J. in Behavioural Mechanisms of Food Selection (ed Hughes, R. N.) 143–167 (Springer, 1990).

Siveter, D. J., Fortey, R. A., Briggs, D. E., Siveter, D. J. & Sutton, M. D. The first Silurian trilobite with three‐dimensionally preserved soft parts reveals novel appendage morphology. Pap. Palaeontol.7, 2245–2253 (2021).10.1002/spp2.1401 DOI

Thomas, A. T. & Holloway, D. J. Classification and phylogeny of the trilobite order Lichida. Philos. Trans. R. Soc. B 321, 179–262 (1988).

Ceccaldi, H. J. in Advances in Tropical Aquaculture. Actes de colloques, Vol. 9 (eds Barret, J. et al.) 243–259 (Institut Français de Recherche pour l’Exploitation de la Mer, 1989).

Vannier, J., Liu, J., Lerosey-Aubril, R., Vinther, J. & Daley, A. C. Sophisticated digestive systems in early arthropods. Nat. Commun.5, 3641 (2014). 10.1038/ncomms4641 PubMed DOI

Fortey, R. A. & Owens, R. M. Feeding habits in trilobites. Palaeontology42, 429–465 (1999).10.1111/1475-4983.00080 DOI

Hegna, T. A. The function of forks: Isotelus‐type hypostomes and trilobite feeding. Lethaia43, 411–419 (2010).10.1111/j.1502-3931.2009.00204.x DOI

McGaw, I. J. & Curtis, D. L. A review of gastric processing in decapod crustaceans. J. Comp. Physiol. B183, 443–465 (2013). 10.1007/s00360-012-0730-3 PubMed DOI

Edgecombe, G. D. Arthropod phylogeny: an overview from the perspectives of morphology, molecular data and the fossil record. Arthropod Struct. Dev.39, 74–87 (2010). 10.1016/j.asd.2009.10.002 PubMed DOI

Scholtz, G. & Edgecombe, G. D. in Crustacea and Arthropod Relationships (eds Koenemann, S. & Jenner R.) 139–165 (CRC, 2005).

Pavasovic, M., Richardson, N. A., Anderson, A. J., Mann, D. & Mather, P. B. Effect of pH, temperature and diet on digestive enzyme profiles in the mud crab, Scylla serrata. Aquaculture242, 641–654 (2004).10.1016/j.aquaculture.2004.08.036 DOI

Mamun, A. A., Begum, M., Mia, M. Y. & Alam, M. J. Food and feeding habits of the mud crab Scylla serrata (Forsskal) in Bangladesh. J. Bangladesh Soc. Agric. Sci. Technol.5, 141–144 (2008).

Viswanathan, C. & Raffi, S. M. The natural diet of the mud crab Scylla olivacea (Herbst, 1896) in Pichavaram mangroves, India. Saudi J. Biol. Sci.22, 698–705 (2015). 10.1016/j.sjbs.2015.08.005 PubMed DOI PMC

Razali, F. N. et al. Updating a new trend of horseshoe crab feeding behavior in captivity: towards a healthy practice of horseshoe crabs rearing. AACL Bioflux13, 1394–1409 (2020).

Liu, X. et al. Effects of ocean acidification on molting, oxidative stress, and gut microbiota in juvenile horseshoe crab Tachypleus tridentatus. Front. Physiol.12, 813582 (2022). 10.3389/fphys.2021.813582 PubMed DOI PMC

Ayali, A. The role of the arthropod stomatogastric nervous system in moulting behaviour and ecdysis. J. Exp. Biol.212, 453–459 (2009). 10.1242/jeb.023879 PubMed DOI

Budil, P. & Bruthansová, J. Moulting in Ordovician dalmanitoid and acastoid trilobites of the Prague Basin. Preliminary observation. Geol. Acta3, 373–384 (2005).

Drage, H. B. Quantifying intra- and interspecific variability in trilobite moulting behaviour across the Palaeozoic. Palaeontol. Electron.22, 34A (2019).

Anh, N. T. N., Ut, V. N., Wille, M., Hoa, N. V. & Sorgeloos, P. Effect of different forms of Artemia biomass as a food source on survival, molting and growth rate of mud crab (Scylla paramamosain). Aquac. Nutr.17, e549–e558 (2011).10.1111/j.1365-2095.2010.00796.x DOI

Loi, A. & Dabard, M. P. Controls of sea level fluctuations on the formation of Ordovician siliceous nodules in terrigenous offshore environments. Sediment. Geol.153, 65–84 (2002).10.1016/S0037-0738(02)00102-1 DOI

Dabard, M. P. & Loi, A. Environmental control on concretion-forming processes: examples from Paleozoic terrigenous sediments of the North Gondwana margin, Armorican Massif (Middle Ordovician and Middle Devonian) and SW Sardinia (Late Ordovician). Sediment. Geol.267, 93–103 (2012).10.1016/j.sedgeo.2012.05.013 DOI