Eocarcinus
Extinct genus of crustaceans
From Wikipedia, the free encyclopedia
Eocarcinus praecursor is a Jurassic species of decapod crustacean, sufficiently distinct from its relatives to be placed in its own family (Eocarcinidae).[1] 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.[2]
| Eocarcinus Temporal range: | |
|---|---|
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| Holotype (top) and paratype (bottom) specimens | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Malacostraca |
| Order: | Decapoda |
| Suborder: | Pleocyemata |
| Infraorder: | Brachyura |
| Family: | †Eocarcinidae Withers, 1932 |
| Genus: | †Eocarcinus Withers, 1932 |
| Species: | †E. praecursor |
| Binomial name | |
| †Eocarcinus praecursor Withers, 1932 | |
Distribution
It lived during the early Pliensbachian age (Lower Jurassic),[3] and has been found in rocks at two sites in the United Kingdom – Mickelton Tunnel (near Aston Magna), Gloucestershire and Runswick Bay, Yorkshire.[4]
Description
In many of its characters, it represents a transitional stage between the Glypheoidea and the Middle Jurassic crabs in the Prosopidae.[3] 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".[5] 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.[6] 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.[2]