ArticleBiology letters2015
Fossilized spermatozoa preserved in a 50-Myr-old annelid cocoon from Antarctica.
Article in Biology letters, 2015. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 9 papers.
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9 citing papers in PubMed, 37 citations in OpenAlex.
- Blood Relatives: Linking Evolutionary History and Conservation of Medicinal Leeches (Evolutionary applications · 2026Article
- The first leech body fossil predates estimated hirudinidan origins by 200 million years.PeerJ · 2025Article
- Probing the Ecology and Climate of the Eocene Southern Ocean With Sand Tiger SharksPaleoceanography and paleoclimatology · 2020Article
- Exceptional preservation of reproductive organs and giant sperm in Cretaceous ostracods.Proceedings. Biological sciences · 2020Article
- Filamentous cyanobacteria preserved in masses of fungal hyphae from the Triassic of Antarctica.PeerJ · 2020Article
- An Eocene orthocone from Antarctica shows convergent evolution of internally shelled cephalopods.PloS one · 2017Article
- New Carcharhiniform Sharks (Chondrichthyes, Elasmobranchii) from the Early to Middle Eocene of Seymour Island, Antarctic Peninsula.Journal of vertebrate paleontology · 2017Article
- Revision of Eocene Antarctic carpet sharks (Elasmobranchii, Orectolobiformes) from Seymour Island, Antarctic Peninsula.Journal of systematic palaeontology · 2017Article
- A new sawshark,Historical biology · 2017Article
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Authors and funding
5 authors at 3 institutions in 3 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
The origin and evolution of clitellate annelids--earthworms, leeches and their relatives--is poorly understood, partly because body fossils of these delicate organisms are exceedingly rare. The distinctive egg cases (cocoons) of Clitellata, however, are relatively common in the fossil record, although their potential for phylogenetic studies has remained largely unexplored. Here, we report the remarkable discovery of fossilized spermatozoa preserved within the secreted wall layers of a 50-Myr-old clitellate cocoon from Antarctica, representing the oldest fossil animal sperm yet known. Sperm characters are highly informative for the classification of extant Annelida. The Antarctic fossil spermatozoa have several features that point to affinities with the peculiar, leech-like 'crayfish worms' (Branchiobdellida). We anticipate that systematic surveys of cocoon fossils coupled with advances in non-destructive analytical methods may open a new window into the evolution of minute, soft-bodied life forms that are otherwise only rarely observed in the fossil record.
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