Eocarcinus

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title: "Eocarcinus" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["crabs", "jurassic-crustaceans", "monotypic-prehistoric-decapod-genera", "fossils-of-great-britain", "fossil-taxa-described-in-1932"] description: "Extinct genus of crustaceans" topic_path: "general/crabs" source: "https://en.wikipedia.org/wiki/Eocarcinus" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Extinct genus of crustaceans ::

| fossil_range = | image = Eocarcinus fossil.jpg | image_caption = Holotype (top) and paratype (bottom) specimens | grandparent_authority = Withers, 1932 | genus = Eocarcinus | parent_authority = Withers, 1932 | species = praecursor | authority = Withers, 1932 ::figure[src="https://upload.wikimedia.org/wikipedia/commons/f/fc/Eocarcinus_reconstructon.jpg" caption="Reconstruction based on 2020 reanalysis"] ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/4/40/Eocarcinus_fossil2.jpg" caption="Additional paratype specimen"] ::

Eocarcinus praecursor is a Jurassic species of decapod crustacean, sufficiently distinct from its relatives to be placed in its own family (Eocarcinidae). Often considered the oldest true crab, it was considered by a 2010 study to be an early member of the Anomura. However, a reanalysis in 2020 again found it to be the earliest known stem-group crab.

Distribution

It lived during the early Pliensbachian age (Lower Jurassic), and has been found in rocks at two sites in the United Kingdom – Mickelton Tunnel (near Aston Magna), Gloucestershire and Runswick Bay, Yorkshire.

Description

In many of its characters, it represents a transitional stage between the Glypheoidea and the Middle Jurassic crabs in the Prosopidae. Since its ancestors were long-tailed decapods, and its successors were short-tailed crabs, Eocarcinus has been described as "the lobster who decided to become a crab". Previously considered to be the oldest known true crab, a 2010 revision concluded that Eocarcinus could not be accommodated among the Brachyura, and was instead transferred to the Anomura. However, a 2020 reanalysis found that it was again the earliest known stem-group crab, but that it had not undergone the process of carcinisation.

References

References

1. (2009). "A classification of living and fossil genera of decapod crustaceans". [[Raffles Bulletin of Zoology]].
2. Scholtz, Gerhard. (November 2020). "Eocarcinus praecursor Withers, 1932 (Malacostraca, Decapoda, Meiura) is a stem group brachyuran". Arthropod Structure & Development.
3. (2008). "Middle and Late Jurassic roots of brachyuran crabs: Palaeoenvironmental distribution during their early evolution". [[Palaeogeography, Palaeoclimatology, Palaeoecology]].
4. (2001). "Une nouvelle famille de Crabes du Crétacé, et la notion de Podotremata Guinot, 1977 (Crustacea, Decapoda, Brachyura)". [[Zoosystema]].
5. Anonymous. (1932). "The Royal Society Conversazione". [[British Medical Journal]].
6. (2010). "Is ''Eocarcinus'' Withers, 1932, a basal brachyuran?". [[Journal of Crustacean Biology]].

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