From tenacious trilobites, to scavenging shrimp, for the last 500 million years of Earth’s history, marine arthropods have scuttled around the sea floor, forming a dominant part of the ocean’s ecosystem. Since the Devonian, these chitinous creatures have taken over the terrestrial realm as spiders, scorpions and springtails.

Despite Arthropoda representing the largest phylum in the animal kingdom, this diverse animal clade is substantially underrepresented in the fossil record compared to their stronger biomineralizing marine friends such as molluscs (Mollusca) and echinoderms (Echinodermata).

Palaeontologists are often faced with the challenge of the fidelity of the fossil record, and for those studying arthropods, this difficulty is exemplified by their poor or weak preservation, despite harbouring mineralised exoskeletons. Not all fossils are made equal, and due to this preservational spectrum, a considerable amount of palaeontological information can be lost from the geological record.

Palaeontologists owe much of their understanding of marine arthropods to Fossil-
Lagerstätte. In 1970, Adolf Seilacher, a German palaeontologist, seminal for his work
on trace fossils and ecological paleobiology, introduced the concept of Lagerstätte
deposits as sites of exceptional preservation (Konservat-Lagerstätte) or of unusual
abundance (Konzentrat-Lagerstätte). These deposits serve as rare windows into
ancient environments and ecosystems, with remarkably informative fossils. Notably,
sites like Walcott’s Cambrian Burgess Shale of Canada, or the Ordovician Fezouata
Formation of Morocco have lent incredible insight into the early evolution of marine
arthropods.

In a new Special Issue in the Journal of Paleontology, Ohio State’s Professor Loren Babcock revisits the arthropod fossil record and discusses how Lagerstätte sites have been the key to unlocking the secrets of marine arthropod evolution by
highlighting key sedimentary occurrences rich in paleontological information.

Babcock focusses on the role of taphonomic associations such as concretionary formation, clustering events, event-bed deposition, and microbial sealing as important processes leading to the preservation of the most useful fossils.

Finally, he emphasises that understanding these multifaceted taphonomic processes and recognising them in the geological record will be key to targeting overlooked sites that might yield Lagerstätte-grade deposits, ultimately contributing to a deeper understanding of marine arthropod evolution, diversity, and ecosystem roles in deep
time.

“Marine arthropod Fossil-Lagerstätten” by Loren E. Babcock has been published
in Journal of Paleontology, published by Cambridge University Press on behalf of the
Paleontological Society. The article is Open Access.